Import Google proto dependencies for the Remote Execution API

This imports protos from https://github.com/googleapis/googleapis/ and
the modules generated with ./setup.py build_grpc.

20 files changed, 2199 insertions, 0 deletions

diff --git a/buildstream/_protos/google/__init__.py b/buildstream/_protos/google/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/buildstream/_protos/google/__init__.py
diff --git a/buildstream/_protos/google/api/__init__.py b/buildstream/_protos/google/api/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/buildstream/_protos/google/api/__init__.py
diff --git a/buildstream/_protos/google/api/annotations.proto b/buildstream/_protos/google/api/annotations.proto
new file mode 100644
index 000000000..85c361b47
--- /dev/null
+++ b/buildstream/_protos/google/api/annotations.proto
@@ -0,0 +1,31 @@
+// Copyright (c) 2015, Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.api;
+
+import "google/api/http.proto";
+import "google/protobuf/descriptor.proto";
+
+option go_package = "google.golang.org/genproto/googleapis/api/annotations;annotations";
+option java_multiple_files = true;
+option java_outer_classname = "AnnotationsProto";
+option java_package = "com.google.api";
+option objc_class_prefix = "GAPI";
+
+extend google.protobuf.MethodOptions {
+  // See `HttpRule`.
+  HttpRule http = 72295728;
+}
diff --git a/buildstream/_protos/google/api/annotations_pb2.py b/buildstream/_protos/google/api/annotations_pb2.py
new file mode 100644
index 000000000..092c46de7
--- /dev/null
+++ b/buildstream/_protos/google/api/annotations_pb2.py
@@ -0,0 +1,46 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: google/api/annotations.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+from google.protobuf import descriptor_pb2
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+from buildstream._protos.google.api import http_pb2 as google_dot_api_dot_http__pb2
+from google.protobuf import descriptor_pb2 as google_dot_protobuf_dot_descriptor__pb2
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='google/api/annotations.proto',
+  package='google.api',
+  syntax='proto3',
+  serialized_pb=_b('\n\x1cgoogle/api/annotations.proto\x12\ngoogle.api\x1a\x15google/api/http.proto\x1a google/protobuf/descriptor.proto:E\n\x04http\x12\x1e.google.protobuf.MethodOptions\x18\xb0\xca\xbc\" \x01(\x0b\x32\x14.google.api.HttpRuleBn\n\x0e\x63om.google.apiB\x10\x41nnotationsProtoP\x01ZAgoogle.golang.org/genproto/googleapis/api/annotations;annotations\xa2\x02\x04GAPIb\x06proto3')
+  ,
+  dependencies=[google_dot_api_dot_http__pb2.DESCRIPTOR,google_dot_protobuf_dot_descriptor__pb2.DESCRIPTOR,])
+
+
+HTTP_FIELD_NUMBER = 72295728
+http = _descriptor.FieldDescriptor(
+  name='http', full_name='google.api.http', index=0,
+  number=72295728, type=11, cpp_type=10, label=1,
+  has_default_value=False, default_value=None,
+  message_type=None, enum_type=None, containing_type=None,
+  is_extension=True, extension_scope=None,
+  options=None, file=DESCRIPTOR)
+
+DESCRIPTOR.extensions_by_name['http'] = http
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+http.message_type = google_dot_api_dot_http__pb2._HTTPRULE
+google_dot_protobuf_dot_descriptor__pb2.MethodOptions.RegisterExtension(http)
+
+DESCRIPTOR.has_options = True
+DESCRIPTOR._options = _descriptor._ParseOptions(descriptor_pb2.FileOptions(), _b('\n\016com.google.apiB\020AnnotationsProtoP\001ZAgoogle.golang.org/genproto/googleapis/api/annotations;annotations\242\002\004GAPI'))
+# @@protoc_insertion_point(module_scope)
diff --git a/buildstream/_protos/google/api/annotations_pb2_grpc.py b/buildstream/_protos/google/api/annotations_pb2_grpc.py
new file mode 100644
index 000000000..a89435267
--- /dev/null
+++ b/buildstream/_protos/google/api/annotations_pb2_grpc.py
@@ -0,0 +1,3 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+import grpc
+
diff --git a/buildstream/_protos/google/api/http.proto b/buildstream/_protos/google/api/http.proto
new file mode 100644
index 000000000..78d515d4b
--- /dev/null
+++ b/buildstream/_protos/google/api/http.proto
@@ -0,0 +1,313 @@
+// Copyright 2018 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.api;
+
+option cc_enable_arenas = true;
+option go_package = "google.golang.org/genproto/googleapis/api/annotations;annotations";
+option java_multiple_files = true;
+option java_outer_classname = "HttpProto";
+option java_package = "com.google.api";
+option objc_class_prefix = "GAPI";
+
+
+// Defines the HTTP configuration for an API service. It contains a list of
+// [HttpRule][google.api.HttpRule], each specifying the mapping of an RPC method
+// to one or more HTTP REST API methods.
+message Http {
+  // A list of HTTP configuration rules that apply to individual API methods.
+  //
+  // **NOTE:** All service configuration rules follow "last one wins" order.
+  repeated HttpRule rules = 1;
+
+  // When set to true, URL path parmeters will be fully URI-decoded except in
+  // cases of single segment matches in reserved expansion, where "%2F" will be
+  // left encoded.
+  //
+  // The default behavior is to not decode RFC 6570 reserved characters in multi
+  // segment matches.
+  bool fully_decode_reserved_expansion = 2;
+}
+
+// `HttpRule` defines the mapping of an RPC method to one or more HTTP
+// REST API methods. The mapping specifies how different portions of the RPC
+// request message are mapped to URL path, URL query parameters, and
+// HTTP request body. The mapping is typically specified as an
+// `google.api.http` annotation on the RPC method,
+// see "google/api/annotations.proto" for details.
+//
+// The mapping consists of a field specifying the path template and
+// method kind.  The path template can refer to fields in the request
+// message, as in the example below which describes a REST GET
+// operation on a resource collection of messages:
+//
+//
+//     service Messaging {
+//       rpc GetMessage(GetMessageRequest) returns (Message) {
+//         option (google.api.http).get = "/v1/messages/{message_id}/{sub.subfield}";
+//       }
+//     }
+//     message GetMessageRequest {
+//       message SubMessage {
+//         string subfield = 1;
+//       }
+//       string message_id = 1; // mapped to the URL
+//       SubMessage sub = 2;    // `sub.subfield` is url-mapped
+//     }
+//     message Message {
+//       string text = 1; // content of the resource
+//     }
+//
+// The same http annotation can alternatively be expressed inside the
+// `GRPC API Configuration` YAML file.
+//
+//     http:
+//       rules:
+//         - selector: <proto_package_name>.Messaging.GetMessage
+//           get: /v1/messages/{message_id}/{sub.subfield}
+//
+// This definition enables an automatic, bidrectional mapping of HTTP
+// JSON to RPC. Example:
+//
+// HTTP | RPC
+// -----|-----
+// `GET /v1/messages/123456/foo`  | `GetMessage(message_id: "123456" sub: SubMessage(subfield: "foo"))`
+//
+// In general, not only fields but also field paths can be referenced
+// from a path pattern. Fields mapped to the path pattern cannot be
+// repeated and must have a primitive (non-message) type.
+//
+// Any fields in the request message which are not bound by the path
+// pattern automatically become (optional) HTTP query
+// parameters. Assume the following definition of the request message:
+//
+//
+//     service Messaging {
+//       rpc GetMessage(GetMessageRequest) returns (Message) {
+//         option (google.api.http).get = "/v1/messages/{message_id}";
+//       }
+//     }
+//     message GetMessageRequest {
+//       message SubMessage {
+//         string subfield = 1;
+//       }
+//       string message_id = 1; // mapped to the URL
+//       int64 revision = 2;    // becomes a parameter
+//       SubMessage sub = 3;    // `sub.subfield` becomes a parameter
+//     }
+//
+//
+// This enables a HTTP JSON to RPC mapping as below:
+//
+// HTTP | RPC
+// -----|-----
+// `GET /v1/messages/123456?revision=2&sub.subfield=foo` | `GetMessage(message_id: "123456" revision: 2 sub: SubMessage(subfield: "foo"))`
+//
+// Note that fields which are mapped to HTTP parameters must have a
+// primitive type or a repeated primitive type. Message types are not
+// allowed. In the case of a repeated type, the parameter can be
+// repeated in the URL, as in `...?param=A&param=B`.
+//
+// For HTTP method kinds which allow a request body, the `body` field
+// specifies the mapping. Consider a REST update method on the
+// message resource collection:
+//
+//
+//     service Messaging {
+//       rpc UpdateMessage(UpdateMessageRequest) returns (Message) {
+//         option (google.api.http) = {
+//           put: "/v1/messages/{message_id}"
+//           body: "message"
+//         };
+//       }
+//     }
+//     message UpdateMessageRequest {
+//       string message_id = 1; // mapped to the URL
+//       Message message = 2;   // mapped to the body
+//     }
+//
+//
+// The following HTTP JSON to RPC mapping is enabled, where the
+// representation of the JSON in the request body is determined by
+// protos JSON encoding:
+//
+// HTTP | RPC
+// -----|-----
+// `PUT /v1/messages/123456 { "text": "Hi!" }` | `UpdateMessage(message_id: "123456" message { text: "Hi!" })`
+//
+// The special name `*` can be used in the body mapping to define that
+// every field not bound by the path template should be mapped to the
+// request body.  This enables the following alternative definition of
+// the update method:
+//
+//     service Messaging {
+//       rpc UpdateMessage(Message) returns (Message) {
+//         option (google.api.http) = {
+//           put: "/v1/messages/{message_id}"
+//           body: "*"
+//         };
+//       }
+//     }
+//     message Message {
+//       string message_id = 1;
+//       string text = 2;
+//     }
+//
+//
+// The following HTTP JSON to RPC mapping is enabled:
+//
+// HTTP | RPC
+// -----|-----
+// `PUT /v1/messages/123456 { "text": "Hi!" }` | `UpdateMessage(message_id: "123456" text: "Hi!")`
+//
+// Note that when using `*` in the body mapping, it is not possible to
+// have HTTP parameters, as all fields not bound by the path end in
+// the body. This makes this option more rarely used in practice of
+// defining REST APIs. The common usage of `*` is in custom methods
+// which don't use the URL at all for transferring data.
+//
+// It is possible to define multiple HTTP methods for one RPC by using
+// the `additional_bindings` option. Example:
+//
+//     service Messaging {
+//       rpc GetMessage(GetMessageRequest) returns (Message) {
+//         option (google.api.http) = {
+//           get: "/v1/messages/{message_id}"
+//           additional_bindings {
+//             get: "/v1/users/{user_id}/messages/{message_id}"
+//           }
+//         };
+//       }
+//     }
+//     message GetMessageRequest {
+//       string message_id = 1;
+//       string user_id = 2;
+//     }
+//
+//
+// This enables the following two alternative HTTP JSON to RPC
+// mappings:
+//
+// HTTP | RPC
+// -----|-----
+// `GET /v1/messages/123456` | `GetMessage(message_id: "123456")`
+// `GET /v1/users/me/messages/123456` | `GetMessage(user_id: "me" message_id: "123456")`
+//
+// # Rules for HTTP mapping
+//
+// The rules for mapping HTTP path, query parameters, and body fields
+// to the request message are as follows:
+//
+// 1. The `body` field specifies either `*` or a field path, or is
+//    omitted. If omitted, it indicates there is no HTTP request body.
+// 2. Leaf fields (recursive expansion of nested messages in the
+//    request) can be classified into three types:
+//     (a) Matched in the URL template.
+//     (b) Covered by body (if body is `*`, everything except (a) fields;
+//         else everything under the body field)
+//     (c) All other fields.
+// 3. URL query parameters found in the HTTP request are mapped to (c) fields.
+// 4. Any body sent with an HTTP request can contain only (b) fields.
+//
+// The syntax of the path template is as follows:
+//
+//     Template = "/" Segments [ Verb ] ;
+//     Segments = Segment { "/" Segment } ;
+//     Segment  = "*" | "**" | LITERAL | Variable ;
+//     Variable = "{" FieldPath [ "=" Segments ] "}" ;
+//     FieldPath = IDENT { "." IDENT } ;
+//     Verb     = ":" LITERAL ;
+//
+// The syntax `*` matches a single path segment. The syntax `**` matches zero
+// or more path segments, which must be the last part of the path except the
+// `Verb`. The syntax `LITERAL` matches literal text in the path.
+//
+// The syntax `Variable` matches part of the URL path as specified by its
+// template. A variable template must not contain other variables. If a variable
+// matches a single path segment, its template may be omitted, e.g. `{var}`
+// is equivalent to `{var=*}`.
+//
+// If a variable contains exactly one path segment, such as `"{var}"` or
+// `"{var=*}"`, when such a variable is expanded into a URL path, all characters
+// except `[-_.~0-9a-zA-Z]` are percent-encoded. Such variables show up in the
+// Discovery Document as `{var}`.
+//
+// If a variable contains one or more path segments, such as `"{var=foo/*}"`
+// or `"{var=**}"`, when such a variable is expanded into a URL path, all
+// characters except `[-_.~/0-9a-zA-Z]` are percent-encoded. Such variables
+// show up in the Discovery Document as `{+var}`.
+//
+// NOTE: While the single segment variable matches the semantics of
+// [RFC 6570](https://tools.ietf.org/html/rfc6570) Section 3.2.2
+// Simple String Expansion, the multi segment variable **does not** match
+// RFC 6570 Reserved Expansion. The reason is that the Reserved Expansion
+// does not expand special characters like `?` and `#`, which would lead
+// to invalid URLs.
+//
+// NOTE: the field paths in variables and in the `body` must not refer to
+// repeated fields or map fields.
+message HttpRule {
+  // Selects methods to which this rule applies.
+  //
+  // Refer to [selector][google.api.DocumentationRule.selector] for syntax details.
+  string selector = 1;
+
+  // Determines the URL pattern is matched by this rules. This pattern can be
+  // used with any of the {get|put|post|delete|patch} methods. A custom method
+  // can be defined using the 'custom' field.
+  oneof pattern {
+    // Used for listing and getting information about resources.
+    string get = 2;
+
+    // Used for updating a resource.
+    string put = 3;
+
+    // Used for creating a resource.
+    string post = 4;
+
+    // Used for deleting a resource.
+    string delete = 5;
+
+    // Used for updating a resource.
+    string patch = 6;
+
+    // The custom pattern is used for specifying an HTTP method that is not
+    // included in the `pattern` field, such as HEAD, or "*" to leave the
+    // HTTP method unspecified for this rule. The wild-card rule is useful
+    // for services that provide content to Web (HTML) clients.
+    CustomHttpPattern custom = 8;
+  }
+
+  // The name of the request field whose value is mapped to the HTTP body, or
+  // `*` for mapping all fields not captured by the path pattern to the HTTP
+  // body. NOTE: the referred field must not be a repeated field and must be
+  // present at the top-level of request message type.
+  string body = 7;
+
+  // Additional HTTP bindings for the selector. Nested bindings must
+  // not contain an `additional_bindings` field themselves (that is,
+  // the nesting may only be one level deep).
+  repeated HttpRule additional_bindings = 11;
+}
+
+// A custom pattern is used for defining custom HTTP verb.
+message CustomHttpPattern {
+  // The name of this custom HTTP verb.
+  string kind = 1;
+
+  // The path matched by this custom verb.
+  string path = 2;
+}
diff --git a/buildstream/_protos/google/api/http_pb2.py b/buildstream/_protos/google/api/http_pb2.py
new file mode 100644
index 000000000..aad9ddb97
--- /dev/null
+++ b/buildstream/_protos/google/api/http_pb2.py
@@ -0,0 +1,243 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: google/api/http.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+from google.protobuf import descriptor_pb2
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='google/api/http.proto',
+  package='google.api',
+  syntax='proto3',
+  serialized_pb=_b('\n\x15google/api/http.proto\x12\ngoogle.api\"T\n\x04Http\x12#\n\x05rules\x18\x01 \x03(\x0b\x32\x14.google.api.HttpRule\x12\'\n\x1f\x66ully_decode_reserved_expansion\x18\x02 \x01(\x08\"\xea\x01\n\x08HttpRule\x12\x10\n\x08selector\x18\x01 \x01(\t\x12\r\n\x03get\x18\x02 \x01(\tH\x00\x12\r\n\x03put\x18\x03 \x01(\tH\x00\x12\x0e\n\x04post\x18\x04 \x01(\tH\x00\x12\x10\n\x06\x64\x65lete\x18\x05 \x01(\tH\x00\x12\x0f\n\x05patch\x18\x06 \x01(\tH\x00\x12/\n\x06\x63ustom\x18\x08 \x01(\x0b\x32\x1d.google.api.CustomHttpPatternH\x00\x12\x0c\n\x04\x62ody\x18\x07 \x01(\t\x12\x31\n\x13\x61\x64\x64itional_bindings\x18\x0b \x03(\x0b\x32\x14.google.api.HttpRuleB\t\n\x07pattern\"/\n\x11\x43ustomHttpPattern\x12\x0c\n\x04kind\x18\x01 \x01(\t\x12\x0c\n\x04path\x18\x02 \x01(\tBj\n\x0e\x63om.google.apiB\tHttpProtoP\x01ZAgoogle.golang.org/genproto/googleapis/api/annotations;annotations\xf8\x01\x01\xa2\x02\x04GAPIb\x06proto3')
+)
+
+
+
+
+_HTTP = _descriptor.Descriptor(
+  name='Http',
+  full_name='google.api.Http',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='rules', full_name='google.api.Http.rules', index=0,
+      number=1, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='fully_decode_reserved_expansion', full_name='google.api.Http.fully_decode_reserved_expansion', index=1,
+      number=2, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=37,
+  serialized_end=121,
+)
+
+
+_HTTPRULE = _descriptor.Descriptor(
+  name='HttpRule',
+  full_name='google.api.HttpRule',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='selector', full_name='google.api.HttpRule.selector', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='get', full_name='google.api.HttpRule.get', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='put', full_name='google.api.HttpRule.put', index=2,
+      number=3, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='post', full_name='google.api.HttpRule.post', index=3,
+      number=4, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='delete', full_name='google.api.HttpRule.delete', index=4,
+      number=5, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='patch', full_name='google.api.HttpRule.patch', index=5,
+      number=6, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='custom', full_name='google.api.HttpRule.custom', index=6,
+      number=8, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='body', full_name='google.api.HttpRule.body', index=7,
+      number=7, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='additional_bindings', full_name='google.api.HttpRule.additional_bindings', index=8,
+      number=11, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+    _descriptor.OneofDescriptor(
+      name='pattern', full_name='google.api.HttpRule.pattern',
+      index=0, containing_type=None, fields=[]),
+  ],
+  serialized_start=124,
+  serialized_end=358,
+)
+
+
+_CUSTOMHTTPPATTERN = _descriptor.Descriptor(
+  name='CustomHttpPattern',
+  full_name='google.api.CustomHttpPattern',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='kind', full_name='google.api.CustomHttpPattern.kind', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='path', full_name='google.api.CustomHttpPattern.path', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=360,
+  serialized_end=407,
+)
+
+_HTTP.fields_by_name['rules'].message_type = _HTTPRULE
+_HTTPRULE.fields_by_name['custom'].message_type = _CUSTOMHTTPPATTERN
+_HTTPRULE.fields_by_name['additional_bindings'].message_type = _HTTPRULE
+_HTTPRULE.oneofs_by_name['pattern'].fields.append(
+  _HTTPRULE.fields_by_name['get'])
+_HTTPRULE.fields_by_name['get'].containing_oneof = _HTTPRULE.oneofs_by_name['pattern']
+_HTTPRULE.oneofs_by_name['pattern'].fields.append(
+  _HTTPRULE.fields_by_name['put'])
+_HTTPRULE.fields_by_name['put'].containing_oneof = _HTTPRULE.oneofs_by_name['pattern']
+_HTTPRULE.oneofs_by_name['pattern'].fields.append(
+  _HTTPRULE.fields_by_name['post'])
+_HTTPRULE.fields_by_name['post'].containing_oneof = _HTTPRULE.oneofs_by_name['pattern']
+_HTTPRULE.oneofs_by_name['pattern'].fields.append(
+  _HTTPRULE.fields_by_name['delete'])
+_HTTPRULE.fields_by_name['delete'].containing_oneof = _HTTPRULE.oneofs_by_name['pattern']
+_HTTPRULE.oneofs_by_name['pattern'].fields.append(
+  _HTTPRULE.fields_by_name['patch'])
+_HTTPRULE.fields_by_name['patch'].containing_oneof = _HTTPRULE.oneofs_by_name['pattern']
+_HTTPRULE.oneofs_by_name['pattern'].fields.append(
+  _HTTPRULE.fields_by_name['custom'])
+_HTTPRULE.fields_by_name['custom'].containing_oneof = _HTTPRULE.oneofs_by_name['pattern']
+DESCRIPTOR.message_types_by_name['Http'] = _HTTP
+DESCRIPTOR.message_types_by_name['HttpRule'] = _HTTPRULE
+DESCRIPTOR.message_types_by_name['CustomHttpPattern'] = _CUSTOMHTTPPATTERN
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+Http = _reflection.GeneratedProtocolMessageType('Http', (_message.Message,), dict(
+  DESCRIPTOR = _HTTP,
+  __module__ = 'google.api.http_pb2'
+  # @@protoc_insertion_point(class_scope:google.api.Http)
+  ))
+_sym_db.RegisterMessage(Http)
+
+HttpRule = _reflection.GeneratedProtocolMessageType('HttpRule', (_message.Message,), dict(
+  DESCRIPTOR = _HTTPRULE,
+  __module__ = 'google.api.http_pb2'
+  # @@protoc_insertion_point(class_scope:google.api.HttpRule)
+  ))
+_sym_db.RegisterMessage(HttpRule)
+
+CustomHttpPattern = _reflection.GeneratedProtocolMessageType('CustomHttpPattern', (_message.Message,), dict(
+  DESCRIPTOR = _CUSTOMHTTPPATTERN,
+  __module__ = 'google.api.http_pb2'
+  # @@protoc_insertion_point(class_scope:google.api.CustomHttpPattern)
+  ))
+_sym_db.RegisterMessage(CustomHttpPattern)
+
+
+DESCRIPTOR.has_options = True
+DESCRIPTOR._options = _descriptor._ParseOptions(descriptor_pb2.FileOptions(), _b('\n\016com.google.apiB\tHttpProtoP\001ZAgoogle.golang.org/genproto/googleapis/api/annotations;annotations\370\001\001\242\002\004GAPI'))
+# @@protoc_insertion_point(module_scope)
diff --git a/buildstream/_protos/google/api/http_pb2_grpc.py b/buildstream/_protos/google/api/http_pb2_grpc.py
new file mode 100644
index 000000000..a89435267
--- /dev/null
+++ b/buildstream/_protos/google/api/http_pb2_grpc.py
@@ -0,0 +1,3 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+import grpc
+
diff --git a/buildstream/_protos/google/bytestream/__init__.py b/buildstream/_protos/google/bytestream/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/buildstream/_protos/google/bytestream/__init__.py
diff --git a/buildstream/_protos/google/bytestream/bytestream.proto b/buildstream/_protos/google/bytestream/bytestream.proto
new file mode 100644
index 000000000..85e386fc2
--- /dev/null
+++ b/buildstream/_protos/google/bytestream/bytestream.proto
@@ -0,0 +1,181 @@
+// Copyright 2016 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.bytestream;
+
+import "google/api/annotations.proto";
+import "google/protobuf/wrappers.proto";
+
+option go_package = "google.golang.org/genproto/googleapis/bytestream;bytestream";
+option java_outer_classname = "ByteStreamProto";
+option java_package = "com.google.bytestream";
+
+
+// #### Introduction
+//
+// The Byte Stream API enables a client to read and write a stream of bytes to
+// and from a resource. Resources have names, and these names are supplied in
+// the API calls below to identify the resource that is being read from or
+// written to.
+//
+// All implementations of the Byte Stream API export the interface defined here:
+//
+// * `Read()`: Reads the contents of a resource.
+//
+// * `Write()`: Writes the contents of a resource. The client can call `Write()`
+//   multiple times with the same resource and can check the status of the write
+//   by calling `QueryWriteStatus()`.
+//
+// #### Service parameters and metadata
+//
+// The ByteStream API provides no direct way to access/modify any metadata
+// associated with the resource.
+//
+// #### Errors
+//
+// The errors returned by the service are in the Google canonical error space.
+service ByteStream {
+  // `Read()` is used to retrieve the contents of a resource as a sequence
+  // of bytes. The bytes are returned in a sequence of responses, and the
+  // responses are delivered as the results of a server-side streaming RPC.
+  rpc Read(ReadRequest) returns (stream ReadResponse);
+
+  // `Write()` is used to send the contents of a resource as a sequence of
+  // bytes. The bytes are sent in a sequence of request protos of a client-side
+  // streaming RPC.
+  //
+  // A `Write()` action is resumable. If there is an error or the connection is
+  // broken during the `Write()`, the client should check the status of the
+  // `Write()` by calling `QueryWriteStatus()` and continue writing from the
+  // returned `committed_size`. This may be less than the amount of data the
+  // client previously sent.
+  //
+  // Calling `Write()` on a resource name that was previously written and
+  // finalized could cause an error, depending on whether the underlying service
+  // allows over-writing of previously written resources.
+  //
+  // When the client closes the request channel, the service will respond with
+  // a `WriteResponse`. The service will not view the resource as `complete`
+  // until the client has sent a `WriteRequest` with `finish_write` set to
+  // `true`. Sending any requests on a stream after sending a request with
+  // `finish_write` set to `true` will cause an error. The client **should**
+  // check the `WriteResponse` it receives to determine how much data the
+  // service was able to commit and whether the service views the resource as
+  // `complete` or not.
+  rpc Write(stream WriteRequest) returns (WriteResponse);
+
+  // `QueryWriteStatus()` is used to find the `committed_size` for a resource
+  // that is being written, which can then be used as the `write_offset` for
+  // the next `Write()` call.
+  //
+  // If the resource does not exist (i.e., the resource has been deleted, or the
+  // first `Write()` has not yet reached the service), this method returns the
+  // error `NOT_FOUND`.
+  //
+  // The client **may** call `QueryWriteStatus()` at any time to determine how
+  // much data has been processed for this resource. This is useful if the
+  // client is buffering data and needs to know which data can be safely
+  // evicted. For any sequence of `QueryWriteStatus()` calls for a given
+  // resource name, the sequence of returned `committed_size` values will be
+  // non-decreasing.
+  rpc QueryWriteStatus(QueryWriteStatusRequest) returns (QueryWriteStatusResponse);
+}
+
+// Request object for ByteStream.Read.
+message ReadRequest {
+  // The name of the resource to read.
+  string resource_name = 1;
+
+  // The offset for the first byte to return in the read, relative to the start
+  // of the resource.
+  //
+  // A `read_offset` that is negative or greater than the size of the resource
+  // will cause an `OUT_OF_RANGE` error.
+  int64 read_offset = 2;
+
+  // The maximum number of `data` bytes the server is allowed to return in the
+  // sum of all `ReadResponse` messages. A `read_limit` of zero indicates that
+  // there is no limit, and a negative `read_limit` will cause an error.
+  //
+  // If the stream returns fewer bytes than allowed by the `read_limit` and no
+  // error occurred, the stream includes all data from the `read_offset` to the
+  // end of the resource.
+  int64 read_limit = 3;
+}
+
+// Response object for ByteStream.Read.
+message ReadResponse {
+  // A portion of the data for the resource. The service **may** leave `data`
+  // empty for any given `ReadResponse`. This enables the service to inform the
+  // client that the request is still live while it is running an operation to
+  // generate more data.
+  bytes data = 10;
+}
+
+// Request object for ByteStream.Write.
+message WriteRequest {
+  // The name of the resource to write. This **must** be set on the first
+  // `WriteRequest` of each `Write()` action. If it is set on subsequent calls,
+  // it **must** match the value of the first request.
+  string resource_name = 1;
+
+  // The offset from the beginning of the resource at which the data should be
+  // written. It is required on all `WriteRequest`s.
+  //
+  // In the first `WriteRequest` of a `Write()` action, it indicates
+  // the initial offset for the `Write()` call. The value **must** be equal to
+  // the `committed_size` that a call to `QueryWriteStatus()` would return.
+  //
+  // On subsequent calls, this value **must** be set and **must** be equal to
+  // the sum of the first `write_offset` and the sizes of all `data` bundles
+  // sent previously on this stream.
+  //
+  // An incorrect value will cause an error.
+  int64 write_offset = 2;
+
+  // If `true`, this indicates that the write is complete. Sending any
+  // `WriteRequest`s subsequent to one in which `finish_write` is `true` will
+  // cause an error.
+  bool finish_write = 3;
+
+  // A portion of the data for the resource. The client **may** leave `data`
+  // empty for any given `WriteRequest`. This enables the client to inform the
+  // service that the request is still live while it is running an operation to
+  // generate more data.
+  bytes data = 10;
+}
+
+// Response object for ByteStream.Write.
+message WriteResponse {
+  // The number of bytes that have been processed for the given resource.
+  int64 committed_size = 1;
+}
+
+// Request object for ByteStream.QueryWriteStatus.
+message QueryWriteStatusRequest {
+  // The name of the resource whose write status is being requested.
+  string resource_name = 1;
+}
+
+// Response object for ByteStream.QueryWriteStatus.
+message QueryWriteStatusResponse {
+  // The number of bytes that have been processed for the given resource.
+  int64 committed_size = 1;
+
+  // `complete` is `true` only if the client has sent a `WriteRequest` with
+  // `finish_write` set to true, and the server has processed that request.
+  bool complete = 2;
+}
diff --git a/buildstream/_protos/google/bytestream/bytestream_pb2.py b/buildstream/_protos/google/bytestream/bytestream_pb2.py
new file mode 100644
index 000000000..c8487d6a0
--- /dev/null
+++ b/buildstream/_protos/google/bytestream/bytestream_pb2.py
@@ -0,0 +1,353 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: google/bytestream/bytestream.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+from google.protobuf import descriptor_pb2
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+from buildstream._protos.google.api import annotations_pb2 as google_dot_api_dot_annotations__pb2
+from google.protobuf import wrappers_pb2 as google_dot_protobuf_dot_wrappers__pb2
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='google/bytestream/bytestream.proto',
+  package='google.bytestream',
+  syntax='proto3',
+  serialized_pb=_b('\n\"google/bytestream/bytestream.proto\x12\x11google.bytestream\x1a\x1cgoogle/api/annotations.proto\x1a\x1egoogle/protobuf/wrappers.proto\"M\n\x0bReadRequest\x12\x15\n\rresource_name\x18\x01 \x01(\t\x12\x13\n\x0bread_offset\x18\x02 \x01(\x03\x12\x12\n\nread_limit\x18\x03 \x01(\x03\"\x1c\n\x0cReadResponse\x12\x0c\n\x04\x64\x61ta\x18\n \x01(\x0c\"_\n\x0cWriteRequest\x12\x15\n\rresource_name\x18\x01 \x01(\t\x12\x14\n\x0cwrite_offset\x18\x02 \x01(\x03\x12\x14\n\x0c\x66inish_write\x18\x03 \x01(\x08\x12\x0c\n\x04\x64\x61ta\x18\n \x01(\x0c\"\'\n\rWriteResponse\x12\x16\n\x0e\x63ommitted_size\x18\x01 \x01(\x03\"0\n\x17QueryWriteStatusRequest\x12\x15\n\rresource_name\x18\x01 \x01(\t\"D\n\x18QueryWriteStatusResponse\x12\x16\n\x0e\x63ommitted_size\x18\x01 \x01(\x03\x12\x10\n\x08\x63omplete\x18\x02 \x01(\x08\x32\x92\x02\n\nByteStream\x12I\n\x04Read\x12\x1e.google.bytestream.ReadRequest\x1a\x1f.google.bytestream.ReadResponse0\x01\x12L\n\x05Write\x12\x1f.google.bytestream.WriteRequest\x1a .google.bytestream.WriteResponse(\x01\x12k\n\x10QueryWriteStatus\x12*.google.bytestream.QueryWriteStatusRequest\x1a+.google.bytestream.QueryWriteStatusResponseBe\n\x15\x63om.google.bytestreamB\x0f\x42yteStreamProtoZ;google.golang.org/genproto/googleapis/bytestream;bytestreamb\x06proto3')
+  ,
+  dependencies=[google_dot_api_dot_annotations__pb2.DESCRIPTOR,google_dot_protobuf_dot_wrappers__pb2.DESCRIPTOR,])
+
+
+
+
+_READREQUEST = _descriptor.Descriptor(
+  name='ReadRequest',
+  full_name='google.bytestream.ReadRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='resource_name', full_name='google.bytestream.ReadRequest.resource_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='read_offset', full_name='google.bytestream.ReadRequest.read_offset', index=1,
+      number=2, type=3, cpp_type=2, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='read_limit', full_name='google.bytestream.ReadRequest.read_limit', index=2,
+      number=3, type=3, cpp_type=2, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=119,
+  serialized_end=196,
+)
+
+
+_READRESPONSE = _descriptor.Descriptor(
+  name='ReadResponse',
+  full_name='google.bytestream.ReadResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='data', full_name='google.bytestream.ReadResponse.data', index=0,
+      number=10, type=12, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b(""),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=198,
+  serialized_end=226,
+)
+
+
+_WRITEREQUEST = _descriptor.Descriptor(
+  name='WriteRequest',
+  full_name='google.bytestream.WriteRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='resource_name', full_name='google.bytestream.WriteRequest.resource_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='write_offset', full_name='google.bytestream.WriteRequest.write_offset', index=1,
+      number=2, type=3, cpp_type=2, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='finish_write', full_name='google.bytestream.WriteRequest.finish_write', index=2,
+      number=3, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='data', full_name='google.bytestream.WriteRequest.data', index=3,
+      number=10, type=12, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b(""),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=228,
+  serialized_end=323,
+)
+
+
+_WRITERESPONSE = _descriptor.Descriptor(
+  name='WriteResponse',
+  full_name='google.bytestream.WriteResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='committed_size', full_name='google.bytestream.WriteResponse.committed_size', index=0,
+      number=1, type=3, cpp_type=2, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=325,
+  serialized_end=364,
+)
+
+
+_QUERYWRITESTATUSREQUEST = _descriptor.Descriptor(
+  name='QueryWriteStatusRequest',
+  full_name='google.bytestream.QueryWriteStatusRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='resource_name', full_name='google.bytestream.QueryWriteStatusRequest.resource_name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=366,
+  serialized_end=414,
+)
+
+
+_QUERYWRITESTATUSRESPONSE = _descriptor.Descriptor(
+  name='QueryWriteStatusResponse',
+  full_name='google.bytestream.QueryWriteStatusResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='committed_size', full_name='google.bytestream.QueryWriteStatusResponse.committed_size', index=0,
+      number=1, type=3, cpp_type=2, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='complete', full_name='google.bytestream.QueryWriteStatusResponse.complete', index=1,
+      number=2, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=416,
+  serialized_end=484,
+)
+
+DESCRIPTOR.message_types_by_name['ReadRequest'] = _READREQUEST
+DESCRIPTOR.message_types_by_name['ReadResponse'] = _READRESPONSE
+DESCRIPTOR.message_types_by_name['WriteRequest'] = _WRITEREQUEST
+DESCRIPTOR.message_types_by_name['WriteResponse'] = _WRITERESPONSE
+DESCRIPTOR.message_types_by_name['QueryWriteStatusRequest'] = _QUERYWRITESTATUSREQUEST
+DESCRIPTOR.message_types_by_name['QueryWriteStatusResponse'] = _QUERYWRITESTATUSRESPONSE
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+ReadRequest = _reflection.GeneratedProtocolMessageType('ReadRequest', (_message.Message,), dict(
+  DESCRIPTOR = _READREQUEST,
+  __module__ = 'google.bytestream.bytestream_pb2'
+  # @@protoc_insertion_point(class_scope:google.bytestream.ReadRequest)
+  ))
+_sym_db.RegisterMessage(ReadRequest)
+
+ReadResponse = _reflection.GeneratedProtocolMessageType('ReadResponse', (_message.Message,), dict(
+  DESCRIPTOR = _READRESPONSE,
+  __module__ = 'google.bytestream.bytestream_pb2'
+  # @@protoc_insertion_point(class_scope:google.bytestream.ReadResponse)
+  ))
+_sym_db.RegisterMessage(ReadResponse)
+
+WriteRequest = _reflection.GeneratedProtocolMessageType('WriteRequest', (_message.Message,), dict(
+  DESCRIPTOR = _WRITEREQUEST,
+  __module__ = 'google.bytestream.bytestream_pb2'
+  # @@protoc_insertion_point(class_scope:google.bytestream.WriteRequest)
+  ))
+_sym_db.RegisterMessage(WriteRequest)
+
+WriteResponse = _reflection.GeneratedProtocolMessageType('WriteResponse', (_message.Message,), dict(
+  DESCRIPTOR = _WRITERESPONSE,
+  __module__ = 'google.bytestream.bytestream_pb2'
+  # @@protoc_insertion_point(class_scope:google.bytestream.WriteResponse)
+  ))
+_sym_db.RegisterMessage(WriteResponse)
+
+QueryWriteStatusRequest = _reflection.GeneratedProtocolMessageType('QueryWriteStatusRequest', (_message.Message,), dict(
+  DESCRIPTOR = _QUERYWRITESTATUSREQUEST,
+  __module__ = 'google.bytestream.bytestream_pb2'
+  # @@protoc_insertion_point(class_scope:google.bytestream.QueryWriteStatusRequest)
+  ))
+_sym_db.RegisterMessage(QueryWriteStatusRequest)
+
+QueryWriteStatusResponse = _reflection.GeneratedProtocolMessageType('QueryWriteStatusResponse', (_message.Message,), dict(
+  DESCRIPTOR = _QUERYWRITESTATUSRESPONSE,
+  __module__ = 'google.bytestream.bytestream_pb2'
+  # @@protoc_insertion_point(class_scope:google.bytestream.QueryWriteStatusResponse)
+  ))
+_sym_db.RegisterMessage(QueryWriteStatusResponse)
+
+
+DESCRIPTOR.has_options = True
+DESCRIPTOR._options = _descriptor._ParseOptions(descriptor_pb2.FileOptions(), _b('\n\025com.google.bytestreamB\017ByteStreamProtoZ;google.golang.org/genproto/googleapis/bytestream;bytestream'))
+
+_BYTESTREAM = _descriptor.ServiceDescriptor(
+  name='ByteStream',
+  full_name='google.bytestream.ByteStream',
+  file=DESCRIPTOR,
+  index=0,
+  options=None,
+  serialized_start=487,
+  serialized_end=761,
+  methods=[
+  _descriptor.MethodDescriptor(
+    name='Read',
+    full_name='google.bytestream.ByteStream.Read',
+    index=0,
+    containing_service=None,
+    input_type=_READREQUEST,
+    output_type=_READRESPONSE,
+    options=None,
+  ),
+  _descriptor.MethodDescriptor(
+    name='Write',
+    full_name='google.bytestream.ByteStream.Write',
+    index=1,
+    containing_service=None,
+    input_type=_WRITEREQUEST,
+    output_type=_WRITERESPONSE,
+    options=None,
+  ),
+  _descriptor.MethodDescriptor(
+    name='QueryWriteStatus',
+    full_name='google.bytestream.ByteStream.QueryWriteStatus',
+    index=2,
+    containing_service=None,
+    input_type=_QUERYWRITESTATUSREQUEST,
+    output_type=_QUERYWRITESTATUSRESPONSE,
+    options=None,
+  ),
+])
+_sym_db.RegisterServiceDescriptor(_BYTESTREAM)
+
+DESCRIPTOR.services_by_name['ByteStream'] = _BYTESTREAM
+
+# @@protoc_insertion_point(module_scope)
diff --git a/buildstream/_protos/google/bytestream/bytestream_pb2_grpc.py b/buildstream/_protos/google/bytestream/bytestream_pb2_grpc.py
new file mode 100644
index 000000000..ef993e040
--- /dev/null
+++ b/buildstream/_protos/google/bytestream/bytestream_pb2_grpc.py
@@ -0,0 +1,160 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+import grpc
+
+from buildstream._protos.google.bytestream import bytestream_pb2 as google_dot_bytestream_dot_bytestream__pb2
+
+
+class ByteStreamStub(object):
+  """#### Introduction
+
+  The Byte Stream API enables a client to read and write a stream of bytes to
+  and from a resource. Resources have names, and these names are supplied in
+  the API calls below to identify the resource that is being read from or
+  written to.
+
+  All implementations of the Byte Stream API export the interface defined here:
+
+  * `Read()`: Reads the contents of a resource.
+
+  * `Write()`: Writes the contents of a resource. The client can call `Write()`
+  multiple times with the same resource and can check the status of the write
+  by calling `QueryWriteStatus()`.
+
+  #### Service parameters and metadata
+
+  The ByteStream API provides no direct way to access/modify any metadata
+  associated with the resource.
+
+  #### Errors
+
+  The errors returned by the service are in the Google canonical error space.
+  """
+
+  def __init__(self, channel):
+    """Constructor.
+
+    Args:
+      channel: A grpc.Channel.
+    """
+    self.Read = channel.unary_stream(
+        '/google.bytestream.ByteStream/Read',
+        request_serializer=google_dot_bytestream_dot_bytestream__pb2.ReadRequest.SerializeToString,
+        response_deserializer=google_dot_bytestream_dot_bytestream__pb2.ReadResponse.FromString,
+        )
+    self.Write = channel.stream_unary(
+        '/google.bytestream.ByteStream/Write',
+        request_serializer=google_dot_bytestream_dot_bytestream__pb2.WriteRequest.SerializeToString,
+        response_deserializer=google_dot_bytestream_dot_bytestream__pb2.WriteResponse.FromString,
+        )
+    self.QueryWriteStatus = channel.unary_unary(
+        '/google.bytestream.ByteStream/QueryWriteStatus',
+        request_serializer=google_dot_bytestream_dot_bytestream__pb2.QueryWriteStatusRequest.SerializeToString,
+        response_deserializer=google_dot_bytestream_dot_bytestream__pb2.QueryWriteStatusResponse.FromString,
+        )
+
+
+class ByteStreamServicer(object):
+  """#### Introduction
+
+  The Byte Stream API enables a client to read and write a stream of bytes to
+  and from a resource. Resources have names, and these names are supplied in
+  the API calls below to identify the resource that is being read from or
+  written to.
+
+  All implementations of the Byte Stream API export the interface defined here:
+
+  * `Read()`: Reads the contents of a resource.
+
+  * `Write()`: Writes the contents of a resource. The client can call `Write()`
+  multiple times with the same resource and can check the status of the write
+  by calling `QueryWriteStatus()`.
+
+  #### Service parameters and metadata
+
+  The ByteStream API provides no direct way to access/modify any metadata
+  associated with the resource.
+
+  #### Errors
+
+  The errors returned by the service are in the Google canonical error space.
+  """
+
+  def Read(self, request, context):
+    """`Read()` is used to retrieve the contents of a resource as a sequence
+    of bytes. The bytes are returned in a sequence of responses, and the
+    responses are delivered as the results of a server-side streaming RPC.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def Write(self, request_iterator, context):
+    """`Write()` is used to send the contents of a resource as a sequence of
+    bytes. The bytes are sent in a sequence of request protos of a client-side
+    streaming RPC.
+
+    A `Write()` action is resumable. If there is an error or the connection is
+    broken during the `Write()`, the client should check the status of the
+    `Write()` by calling `QueryWriteStatus()` and continue writing from the
+    returned `committed_size`. This may be less than the amount of data the
+    client previously sent.
+
+    Calling `Write()` on a resource name that was previously written and
+    finalized could cause an error, depending on whether the underlying service
+    allows over-writing of previously written resources.
+
+    When the client closes the request channel, the service will respond with
+    a `WriteResponse`. The service will not view the resource as `complete`
+    until the client has sent a `WriteRequest` with `finish_write` set to
+    `true`. Sending any requests on a stream after sending a request with
+    `finish_write` set to `true` will cause an error. The client **should**
+    check the `WriteResponse` it receives to determine how much data the
+    service was able to commit and whether the service views the resource as
+    `complete` or not.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def QueryWriteStatus(self, request, context):
+    """`QueryWriteStatus()` is used to find the `committed_size` for a resource
+    that is being written, which can then be used as the `write_offset` for
+    the next `Write()` call.
+
+    If the resource does not exist (i.e., the resource has been deleted, or the
+    first `Write()` has not yet reached the service), this method returns the
+    error `NOT_FOUND`.
+
+    The client **may** call `QueryWriteStatus()` at any time to determine how
+    much data has been processed for this resource. This is useful if the
+    client is buffering data and needs to know which data can be safely
+    evicted. For any sequence of `QueryWriteStatus()` calls for a given
+    resource name, the sequence of returned `committed_size` values will be
+    non-decreasing.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+
+def add_ByteStreamServicer_to_server(servicer, server):
+  rpc_method_handlers = {
+      'Read': grpc.unary_stream_rpc_method_handler(
+          servicer.Read,
+          request_deserializer=google_dot_bytestream_dot_bytestream__pb2.ReadRequest.FromString,
+          response_serializer=google_dot_bytestream_dot_bytestream__pb2.ReadResponse.SerializeToString,
+      ),
+      'Write': grpc.stream_unary_rpc_method_handler(
+          servicer.Write,
+          request_deserializer=google_dot_bytestream_dot_bytestream__pb2.WriteRequest.FromString,
+          response_serializer=google_dot_bytestream_dot_bytestream__pb2.WriteResponse.SerializeToString,
+      ),
+      'QueryWriteStatus': grpc.unary_unary_rpc_method_handler(
+          servicer.QueryWriteStatus,
+          request_deserializer=google_dot_bytestream_dot_bytestream__pb2.QueryWriteStatusRequest.FromString,
+          response_serializer=google_dot_bytestream_dot_bytestream__pb2.QueryWriteStatusResponse.SerializeToString,
+      ),
+  }
+  generic_handler = grpc.method_handlers_generic_handler(
+      'google.bytestream.ByteStream', rpc_method_handlers)
+  server.add_generic_rpc_handlers((generic_handler,))
diff --git a/buildstream/_protos/google/longrunning/__init__.py b/buildstream/_protos/google/longrunning/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/buildstream/_protos/google/longrunning/__init__.py
diff --git a/buildstream/_protos/google/longrunning/operations.proto b/buildstream/_protos/google/longrunning/operations.proto
new file mode 100644
index 000000000..76fef29c3
--- /dev/null
+++ b/buildstream/_protos/google/longrunning/operations.proto
@@ -0,0 +1,160 @@
+// Copyright 2016 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.longrunning;
+
+import "google/api/annotations.proto";
+import "google/protobuf/any.proto";
+import "google/protobuf/empty.proto";
+import "google/rpc/status.proto";
+
+option csharp_namespace = "Google.LongRunning";
+option go_package = "google.golang.org/genproto/googleapis/longrunning;longrunning";
+option java_multiple_files = true;
+option java_outer_classname = "OperationsProto";
+option java_package = "com.google.longrunning";
+option php_namespace = "Google\\LongRunning";
+
+
+// Manages long-running operations with an API service.
+//
+// When an API method normally takes long time to complete, it can be designed
+// to return [Operation][google.longrunning.Operation] to the client, and the client can use this
+// interface to receive the real response asynchronously by polling the
+// operation resource, or pass the operation resource to another API (such as
+// Google Cloud Pub/Sub API) to receive the response.  Any API service that
+// returns long-running operations should implement the `Operations` interface
+// so developers can have a consistent client experience.
+service Operations {
+  // Lists operations that match the specified filter in the request. If the
+  // server doesn't support this method, it returns `UNIMPLEMENTED`.
+  //
+  // NOTE: the `name` binding below allows API services to override the binding
+  // to use different resource name schemes, such as `users/*/operations`.
+  rpc ListOperations(ListOperationsRequest) returns (ListOperationsResponse) {
+    option (google.api.http) = { get: "/v1/{name=operations}" };
+  }
+
+  // Gets the latest state of a long-running operation.  Clients can use this
+  // method to poll the operation result at intervals as recommended by the API
+  // service.
+  rpc GetOperation(GetOperationRequest) returns (Operation) {
+    option (google.api.http) = { get: "/v1/{name=operations/**}" };
+  }
+
+  // Deletes a long-running operation. This method indicates that the client is
+  // no longer interested in the operation result. It does not cancel the
+  // operation. If the server doesn't support this method, it returns
+  // `google.rpc.Code.UNIMPLEMENTED`.
+  rpc DeleteOperation(DeleteOperationRequest) returns (google.protobuf.Empty) {
+    option (google.api.http) = { delete: "/v1/{name=operations/**}" };
+  }
+
+  // Starts asynchronous cancellation on a long-running operation.  The server
+  // makes a best effort to cancel the operation, but success is not
+  // guaranteed.  If the server doesn't support this method, it returns
+  // `google.rpc.Code.UNIMPLEMENTED`.  Clients can use
+  // [Operations.GetOperation][google.longrunning.Operations.GetOperation] or
+  // other methods to check whether the cancellation succeeded or whether the
+  // operation completed despite cancellation. On successful cancellation,
+  // the operation is not deleted; instead, it becomes an operation with
+  // an [Operation.error][google.longrunning.Operation.error] value with a [google.rpc.Status.code][google.rpc.Status.code] of 1,
+  // corresponding to `Code.CANCELLED`.
+  rpc CancelOperation(CancelOperationRequest) returns (google.protobuf.Empty) {
+    option (google.api.http) = { post: "/v1/{name=operations/**}:cancel" body: "*" };
+  }
+}
+
+// This resource represents a long-running operation that is the result of a
+// network API call.
+message Operation {
+  // The server-assigned name, which is only unique within the same service that
+  // originally returns it. If you use the default HTTP mapping, the
+  // `name` should have the format of `operations/some/unique/name`.
+  string name = 1;
+
+  // Service-specific metadata associated with the operation.  It typically
+  // contains progress information and common metadata such as create time.
+  // Some services might not provide such metadata.  Any method that returns a
+  // long-running operation should document the metadata type, if any.
+  google.protobuf.Any metadata = 2;
+
+  // If the value is `false`, it means the operation is still in progress.
+  // If true, the operation is completed, and either `error` or `response` is
+  // available.
+  bool done = 3;
+
+  // The operation result, which can be either an `error` or a valid `response`.
+  // If `done` == `false`, neither `error` nor `response` is set.
+  // If `done` == `true`, exactly one of `error` or `response` is set.
+  oneof result {
+    // The error result of the operation in case of failure or cancellation.
+    google.rpc.Status error = 4;
+
+    // The normal response of the operation in case of success.  If the original
+    // method returns no data on success, such as `Delete`, the response is
+    // `google.protobuf.Empty`.  If the original method is standard
+    // `Get`/`Create`/`Update`, the response should be the resource.  For other
+    // methods, the response should have the type `XxxResponse`, where `Xxx`
+    // is the original method name.  For example, if the original method name
+    // is `TakeSnapshot()`, the inferred response type is
+    // `TakeSnapshotResponse`.
+    google.protobuf.Any response = 5;
+  }
+}
+
+// The request message for [Operations.GetOperation][google.longrunning.Operations.GetOperation].
+message GetOperationRequest {
+  // The name of the operation resource.
+  string name = 1;
+}
+
+// The request message for [Operations.ListOperations][google.longrunning.Operations.ListOperations].
+message ListOperationsRequest {
+  // The name of the operation collection.
+  string name = 4;
+
+  // The standard list filter.
+  string filter = 1;
+
+  // The standard list page size.
+  int32 page_size = 2;
+
+  // The standard list page token.
+  string page_token = 3;
+}
+
+// The response message for [Operations.ListOperations][google.longrunning.Operations.ListOperations].
+message ListOperationsResponse {
+  // A list of operations that matches the specified filter in the request.
+  repeated Operation operations = 1;
+
+  // The standard List next-page token.
+  string next_page_token = 2;
+}
+
+// The request message for [Operations.CancelOperation][google.longrunning.Operations.CancelOperation].
+message CancelOperationRequest {
+  // The name of the operation resource to be cancelled.
+  string name = 1;
+}
+
+// The request message for [Operations.DeleteOperation][google.longrunning.Operations.DeleteOperation].
+message DeleteOperationRequest {
+  // The name of the operation resource to be deleted.
+  string name = 1;
+}
+
diff --git a/buildstream/_protos/google/longrunning/operations_pb2.py b/buildstream/_protos/google/longrunning/operations_pb2.py
new file mode 100644
index 000000000..9fd89937f
--- /dev/null
+++ b/buildstream/_protos/google/longrunning/operations_pb2.py
@@ -0,0 +1,391 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: google/longrunning/operations.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+from google.protobuf import descriptor_pb2
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+from buildstream._protos.google.api import annotations_pb2 as google_dot_api_dot_annotations__pb2
+from google.protobuf import any_pb2 as google_dot_protobuf_dot_any__pb2
+from google.protobuf import empty_pb2 as google_dot_protobuf_dot_empty__pb2
+from buildstream._protos.google.rpc import status_pb2 as google_dot_rpc_dot_status__pb2
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='google/longrunning/operations.proto',
+  package='google.longrunning',
+  syntax='proto3',
+  serialized_pb=_b('\n#google/longrunning/operations.proto\x12\x12google.longrunning\x1a\x1cgoogle/api/annotations.proto\x1a\x19google/protobuf/any.proto\x1a\x1bgoogle/protobuf/empty.proto\x1a\x17google/rpc/status.proto\"\xa8\x01\n\tOperation\x12\x0c\n\x04name\x18\x01 \x01(\t\x12&\n\x08metadata\x18\x02 \x01(\x0b\x32\x14.google.protobuf.Any\x12\x0c\n\x04\x64one\x18\x03 \x01(\x08\x12#\n\x05\x65rror\x18\x04 \x01(\x0b\x32\x12.google.rpc.StatusH\x00\x12(\n\x08response\x18\x05 \x01(\x0b\x32\x14.google.protobuf.AnyH\x00\x42\x08\n\x06result\"#\n\x13GetOperationRequest\x12\x0c\n\x04name\x18\x01 \x01(\t\"\\\n\x15ListOperationsRequest\x12\x0c\n\x04name\x18\x04 \x01(\t\x12\x0e\n\x06\x66ilter\x18\x01 \x01(\t\x12\x11\n\tpage_size\x18\x02 \x01(\x05\x12\x12\n\npage_token\x18\x03 \x01(\t\"d\n\x16ListOperationsResponse\x12\x31\n\noperations\x18\x01 \x03(\x0b\x32\x1d.google.longrunning.Operation\x12\x17\n\x0fnext_page_token\x18\x02 \x01(\t\"&\n\x16\x43\x61ncelOperationRequest\x12\x0c\n\x04name\x18\x01 \x01(\t\"&\n\x16\x44\x65leteOperationRequest\x12\x0c\n\x04name\x18\x01 \x01(\t2\x8c\x04\n\nOperations\x12\x86\x01\n\x0eListOperations\x12).google.longrunning.ListOperationsRequest\x1a*.google.longrunning.ListOperationsResponse\"\x1d\x82\xd3\xe4\x93\x02\x17\x12\x15/v1/{name=operations}\x12x\n\x0cGetOperation\x12\'.google.longrunning.GetOperationRequest\x1a\x1d.google.longrunning.Operation\" \x82\xd3\xe4\x93\x02\x1a\x12\x18/v1/{name=operations/**}\x12w\n\x0f\x44\x65leteOperation\x12*.google.longrunning.DeleteOperationRequest\x1a\x16.google.protobuf.Empty\" \x82\xd3\xe4\x93\x02\x1a*\x18/v1/{name=operations/**}\x12\x81\x01\n\x0f\x43\x61ncelOperation\x12*.google.longrunning.CancelOperationRequest\x1a\x16.google.protobuf.Empty\"*\x82\xd3\xe4\x93\x02$\"\x1f/v1/{name=operations/**}:cancel:\x01*B\x94\x01\n\x16\x63om.google.longrunningB\x0fOperationsProtoP\x01Z=google.golang.org/genproto/googleapis/longrunning;longrunning\xaa\x02\x12Google.LongRunning\xca\x02\x12Google\\LongRunningb\x06proto3')
+  ,
+  dependencies=[google_dot_api_dot_annotations__pb2.DESCRIPTOR,google_dot_protobuf_dot_any__pb2.DESCRIPTOR,google_dot_protobuf_dot_empty__pb2.DESCRIPTOR,google_dot_rpc_dot_status__pb2.DESCRIPTOR,])
+
+
+
+
+_OPERATION = _descriptor.Descriptor(
+  name='Operation',
+  full_name='google.longrunning.Operation',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='google.longrunning.Operation.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='metadata', full_name='google.longrunning.Operation.metadata', index=1,
+      number=2, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='done', full_name='google.longrunning.Operation.done', index=2,
+      number=3, type=8, cpp_type=7, label=1,
+      has_default_value=False, default_value=False,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='error', full_name='google.longrunning.Operation.error', index=3,
+      number=4, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='response', full_name='google.longrunning.Operation.response', index=4,
+      number=5, type=11, cpp_type=10, label=1,
+      has_default_value=False, default_value=None,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+    _descriptor.OneofDescriptor(
+      name='result', full_name='google.longrunning.Operation.result',
+      index=0, containing_type=None, fields=[]),
+  ],
+  serialized_start=171,
+  serialized_end=339,
+)
+
+
+_GETOPERATIONREQUEST = _descriptor.Descriptor(
+  name='GetOperationRequest',
+  full_name='google.longrunning.GetOperationRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='google.longrunning.GetOperationRequest.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=341,
+  serialized_end=376,
+)
+
+
+_LISTOPERATIONSREQUEST = _descriptor.Descriptor(
+  name='ListOperationsRequest',
+  full_name='google.longrunning.ListOperationsRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='google.longrunning.ListOperationsRequest.name', index=0,
+      number=4, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='filter', full_name='google.longrunning.ListOperationsRequest.filter', index=1,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='page_size', full_name='google.longrunning.ListOperationsRequest.page_size', index=2,
+      number=2, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='page_token', full_name='google.longrunning.ListOperationsRequest.page_token', index=3,
+      number=3, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=378,
+  serialized_end=470,
+)
+
+
+_LISTOPERATIONSRESPONSE = _descriptor.Descriptor(
+  name='ListOperationsResponse',
+  full_name='google.longrunning.ListOperationsResponse',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='operations', full_name='google.longrunning.ListOperationsResponse.operations', index=0,
+      number=1, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='next_page_token', full_name='google.longrunning.ListOperationsResponse.next_page_token', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=472,
+  serialized_end=572,
+)
+
+
+_CANCELOPERATIONREQUEST = _descriptor.Descriptor(
+  name='CancelOperationRequest',
+  full_name='google.longrunning.CancelOperationRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='google.longrunning.CancelOperationRequest.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=574,
+  serialized_end=612,
+)
+
+
+_DELETEOPERATIONREQUEST = _descriptor.Descriptor(
+  name='DeleteOperationRequest',
+  full_name='google.longrunning.DeleteOperationRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='name', full_name='google.longrunning.DeleteOperationRequest.name', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=614,
+  serialized_end=652,
+)
+
+_OPERATION.fields_by_name['metadata'].message_type = google_dot_protobuf_dot_any__pb2._ANY
+_OPERATION.fields_by_name['error'].message_type = google_dot_rpc_dot_status__pb2._STATUS
+_OPERATION.fields_by_name['response'].message_type = google_dot_protobuf_dot_any__pb2._ANY
+_OPERATION.oneofs_by_name['result'].fields.append(
+  _OPERATION.fields_by_name['error'])
+_OPERATION.fields_by_name['error'].containing_oneof = _OPERATION.oneofs_by_name['result']
+_OPERATION.oneofs_by_name['result'].fields.append(
+  _OPERATION.fields_by_name['response'])
+_OPERATION.fields_by_name['response'].containing_oneof = _OPERATION.oneofs_by_name['result']
+_LISTOPERATIONSRESPONSE.fields_by_name['operations'].message_type = _OPERATION
+DESCRIPTOR.message_types_by_name['Operation'] = _OPERATION
+DESCRIPTOR.message_types_by_name['GetOperationRequest'] = _GETOPERATIONREQUEST
+DESCRIPTOR.message_types_by_name['ListOperationsRequest'] = _LISTOPERATIONSREQUEST
+DESCRIPTOR.message_types_by_name['ListOperationsResponse'] = _LISTOPERATIONSRESPONSE
+DESCRIPTOR.message_types_by_name['CancelOperationRequest'] = _CANCELOPERATIONREQUEST
+DESCRIPTOR.message_types_by_name['DeleteOperationRequest'] = _DELETEOPERATIONREQUEST
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+Operation = _reflection.GeneratedProtocolMessageType('Operation', (_message.Message,), dict(
+  DESCRIPTOR = _OPERATION,
+  __module__ = 'google.longrunning.operations_pb2'
+  # @@protoc_insertion_point(class_scope:google.longrunning.Operation)
+  ))
+_sym_db.RegisterMessage(Operation)
+
+GetOperationRequest = _reflection.GeneratedProtocolMessageType('GetOperationRequest', (_message.Message,), dict(
+  DESCRIPTOR = _GETOPERATIONREQUEST,
+  __module__ = 'google.longrunning.operations_pb2'
+  # @@protoc_insertion_point(class_scope:google.longrunning.GetOperationRequest)
+  ))
+_sym_db.RegisterMessage(GetOperationRequest)
+
+ListOperationsRequest = _reflection.GeneratedProtocolMessageType('ListOperationsRequest', (_message.Message,), dict(
+  DESCRIPTOR = _LISTOPERATIONSREQUEST,
+  __module__ = 'google.longrunning.operations_pb2'
+  # @@protoc_insertion_point(class_scope:google.longrunning.ListOperationsRequest)
+  ))
+_sym_db.RegisterMessage(ListOperationsRequest)
+
+ListOperationsResponse = _reflection.GeneratedProtocolMessageType('ListOperationsResponse', (_message.Message,), dict(
+  DESCRIPTOR = _LISTOPERATIONSRESPONSE,
+  __module__ = 'google.longrunning.operations_pb2'
+  # @@protoc_insertion_point(class_scope:google.longrunning.ListOperationsResponse)
+  ))
+_sym_db.RegisterMessage(ListOperationsResponse)
+
+CancelOperationRequest = _reflection.GeneratedProtocolMessageType('CancelOperationRequest', (_message.Message,), dict(
+  DESCRIPTOR = _CANCELOPERATIONREQUEST,
+  __module__ = 'google.longrunning.operations_pb2'
+  # @@protoc_insertion_point(class_scope:google.longrunning.CancelOperationRequest)
+  ))
+_sym_db.RegisterMessage(CancelOperationRequest)
+
+DeleteOperationRequest = _reflection.GeneratedProtocolMessageType('DeleteOperationRequest', (_message.Message,), dict(
+  DESCRIPTOR = _DELETEOPERATIONREQUEST,
+  __module__ = 'google.longrunning.operations_pb2'
+  # @@protoc_insertion_point(class_scope:google.longrunning.DeleteOperationRequest)
+  ))
+_sym_db.RegisterMessage(DeleteOperationRequest)
+
+
+DESCRIPTOR.has_options = True
+DESCRIPTOR._options = _descriptor._ParseOptions(descriptor_pb2.FileOptions(), _b('\n\026com.google.longrunningB\017OperationsProtoP\001Z=google.golang.org/genproto/googleapis/longrunning;longrunning\252\002\022Google.LongRunning\312\002\022Google\\LongRunning'))
+
+_OPERATIONS = _descriptor.ServiceDescriptor(
+  name='Operations',
+  full_name='google.longrunning.Operations',
+  file=DESCRIPTOR,
+  index=0,
+  options=None,
+  serialized_start=655,
+  serialized_end=1179,
+  methods=[
+  _descriptor.MethodDescriptor(
+    name='ListOperations',
+    full_name='google.longrunning.Operations.ListOperations',
+    index=0,
+    containing_service=None,
+    input_type=_LISTOPERATIONSREQUEST,
+    output_type=_LISTOPERATIONSRESPONSE,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002\027\022\025/v1/{name=operations}')),
+  ),
+  _descriptor.MethodDescriptor(
+    name='GetOperation',
+    full_name='google.longrunning.Operations.GetOperation',
+    index=1,
+    containing_service=None,
+    input_type=_GETOPERATIONREQUEST,
+    output_type=_OPERATION,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002\032\022\030/v1/{name=operations/**}')),
+  ),
+  _descriptor.MethodDescriptor(
+    name='DeleteOperation',
+    full_name='google.longrunning.Operations.DeleteOperation',
+    index=2,
+    containing_service=None,
+    input_type=_DELETEOPERATIONREQUEST,
+    output_type=google_dot_protobuf_dot_empty__pb2._EMPTY,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002\032*\030/v1/{name=operations/**}')),
+  ),
+  _descriptor.MethodDescriptor(
+    name='CancelOperation',
+    full_name='google.longrunning.Operations.CancelOperation',
+    index=3,
+    containing_service=None,
+    input_type=_CANCELOPERATIONREQUEST,
+    output_type=google_dot_protobuf_dot_empty__pb2._EMPTY,
+    options=_descriptor._ParseOptions(descriptor_pb2.MethodOptions(), _b('\202\323\344\223\002$\"\037/v1/{name=operations/**}:cancel:\001*')),
+  ),
+])
+_sym_db.RegisterServiceDescriptor(_OPERATIONS)
+
+DESCRIPTOR.services_by_name['Operations'] = _OPERATIONS
+
+# @@protoc_insertion_point(module_scope)
diff --git a/buildstream/_protos/google/longrunning/operations_pb2_grpc.py b/buildstream/_protos/google/longrunning/operations_pb2_grpc.py
new file mode 100644
index 000000000..8f89862e7
--- /dev/null
+++ b/buildstream/_protos/google/longrunning/operations_pb2_grpc.py
@@ -0,0 +1,132 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+import grpc
+
+from buildstream._protos.google.longrunning import operations_pb2 as google_dot_longrunning_dot_operations__pb2
+from google.protobuf import empty_pb2 as google_dot_protobuf_dot_empty__pb2
+
+
+class OperationsStub(object):
+  """Manages long-running operations with an API service.
+
+  When an API method normally takes long time to complete, it can be designed
+  to return [Operation][google.longrunning.Operation] to the client, and the client can use this
+  interface to receive the real response asynchronously by polling the
+  operation resource, or pass the operation resource to another API (such as
+  Google Cloud Pub/Sub API) to receive the response.  Any API service that
+  returns long-running operations should implement the `Operations` interface
+  so developers can have a consistent client experience.
+  """
+
+  def __init__(self, channel):
+    """Constructor.
+
+    Args:
+      channel: A grpc.Channel.
+    """
+    self.ListOperations = channel.unary_unary(
+        '/google.longrunning.Operations/ListOperations',
+        request_serializer=google_dot_longrunning_dot_operations__pb2.ListOperationsRequest.SerializeToString,
+        response_deserializer=google_dot_longrunning_dot_operations__pb2.ListOperationsResponse.FromString,
+        )
+    self.GetOperation = channel.unary_unary(
+        '/google.longrunning.Operations/GetOperation',
+        request_serializer=google_dot_longrunning_dot_operations__pb2.GetOperationRequest.SerializeToString,
+        response_deserializer=google_dot_longrunning_dot_operations__pb2.Operation.FromString,
+        )
+    self.DeleteOperation = channel.unary_unary(
+        '/google.longrunning.Operations/DeleteOperation',
+        request_serializer=google_dot_longrunning_dot_operations__pb2.DeleteOperationRequest.SerializeToString,
+        response_deserializer=google_dot_protobuf_dot_empty__pb2.Empty.FromString,
+        )
+    self.CancelOperation = channel.unary_unary(
+        '/google.longrunning.Operations/CancelOperation',
+        request_serializer=google_dot_longrunning_dot_operations__pb2.CancelOperationRequest.SerializeToString,
+        response_deserializer=google_dot_protobuf_dot_empty__pb2.Empty.FromString,
+        )
+
+
+class OperationsServicer(object):
+  """Manages long-running operations with an API service.
+
+  When an API method normally takes long time to complete, it can be designed
+  to return [Operation][google.longrunning.Operation] to the client, and the client can use this
+  interface to receive the real response asynchronously by polling the
+  operation resource, or pass the operation resource to another API (such as
+  Google Cloud Pub/Sub API) to receive the response.  Any API service that
+  returns long-running operations should implement the `Operations` interface
+  so developers can have a consistent client experience.
+  """
+
+  def ListOperations(self, request, context):
+    """Lists operations that match the specified filter in the request. If the
+    server doesn't support this method, it returns `UNIMPLEMENTED`.
+
+    NOTE: the `name` binding below allows API services to override the binding
+    to use different resource name schemes, such as `users/*/operations`.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def GetOperation(self, request, context):
+    """Gets the latest state of a long-running operation.  Clients can use this
+    method to poll the operation result at intervals as recommended by the API
+    service.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def DeleteOperation(self, request, context):
+    """Deletes a long-running operation. This method indicates that the client is
+    no longer interested in the operation result. It does not cancel the
+    operation. If the server doesn't support this method, it returns
+    `google.rpc.Code.UNIMPLEMENTED`.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+  def CancelOperation(self, request, context):
+    """Starts asynchronous cancellation on a long-running operation.  The server
+    makes a best effort to cancel the operation, but success is not
+    guaranteed.  If the server doesn't support this method, it returns
+    `google.rpc.Code.UNIMPLEMENTED`.  Clients can use
+    [Operations.GetOperation][google.longrunning.Operations.GetOperation] or
+    other methods to check whether the cancellation succeeded or whether the
+    operation completed despite cancellation. On successful cancellation,
+    the operation is not deleted; instead, it becomes an operation with
+    an [Operation.error][google.longrunning.Operation.error] value with a [google.rpc.Status.code][google.rpc.Status.code] of 1,
+    corresponding to `Code.CANCELLED`.
+    """
+    context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+    context.set_details('Method not implemented!')
+    raise NotImplementedError('Method not implemented!')
+
+
+def add_OperationsServicer_to_server(servicer, server):
+  rpc_method_handlers = {
+      'ListOperations': grpc.unary_unary_rpc_method_handler(
+          servicer.ListOperations,
+          request_deserializer=google_dot_longrunning_dot_operations__pb2.ListOperationsRequest.FromString,
+          response_serializer=google_dot_longrunning_dot_operations__pb2.ListOperationsResponse.SerializeToString,
+      ),
+      'GetOperation': grpc.unary_unary_rpc_method_handler(
+          servicer.GetOperation,
+          request_deserializer=google_dot_longrunning_dot_operations__pb2.GetOperationRequest.FromString,
+          response_serializer=google_dot_longrunning_dot_operations__pb2.Operation.SerializeToString,
+      ),
+      'DeleteOperation': grpc.unary_unary_rpc_method_handler(
+          servicer.DeleteOperation,
+          request_deserializer=google_dot_longrunning_dot_operations__pb2.DeleteOperationRequest.FromString,
+          response_serializer=google_dot_protobuf_dot_empty__pb2.Empty.SerializeToString,
+      ),
+      'CancelOperation': grpc.unary_unary_rpc_method_handler(
+          servicer.CancelOperation,
+          request_deserializer=google_dot_longrunning_dot_operations__pb2.CancelOperationRequest.FromString,
+          response_serializer=google_dot_protobuf_dot_empty__pb2.Empty.SerializeToString,
+      ),
+  }
+  generic_handler = grpc.method_handlers_generic_handler(
+      'google.longrunning.Operations', rpc_method_handlers)
+  server.add_generic_rpc_handlers((generic_handler,))
diff --git a/buildstream/_protos/google/rpc/__init__.py b/buildstream/_protos/google/rpc/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/buildstream/_protos/google/rpc/__init__.py
diff --git a/buildstream/_protos/google/rpc/status.proto b/buildstream/_protos/google/rpc/status.proto
new file mode 100644
index 000000000..0839ee966
--- /dev/null
+++ b/buildstream/_protos/google/rpc/status.proto
@@ -0,0 +1,92 @@
+// Copyright 2017 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.rpc;
+
+import "google/protobuf/any.proto";
+
+option go_package = "google.golang.org/genproto/googleapis/rpc/status;status";
+option java_multiple_files = true;
+option java_outer_classname = "StatusProto";
+option java_package = "com.google.rpc";
+option objc_class_prefix = "RPC";
+
+
+// The `Status` type defines a logical error model that is suitable for different
+// programming environments, including REST APIs and RPC APIs. It is used by
+// [gRPC](https://github.com/grpc). The error model is designed to be:
+//
+// - Simple to use and understand for most users
+// - Flexible enough to meet unexpected needs
+//
+// # Overview
+//
+// The `Status` message contains three pieces of data: error code, error message,
+// and error details. The error code should be an enum value of
+// [google.rpc.Code][google.rpc.Code], but it may accept additional error codes if needed.  The
+// error message should be a developer-facing English message that helps
+// developers *understand* and *resolve* the error. If a localized user-facing
+// error message is needed, put the localized message in the error details or
+// localize it in the client. The optional error details may contain arbitrary
+// information about the error. There is a predefined set of error detail types
+// in the package `google.rpc` that can be used for common error conditions.
+//
+// # Language mapping
+//
+// The `Status` message is the logical representation of the error model, but it
+// is not necessarily the actual wire format. When the `Status` message is
+// exposed in different client libraries and different wire protocols, it can be
+// mapped differently. For example, it will likely be mapped to some exceptions
+// in Java, but more likely mapped to some error codes in C.
+//
+// # Other uses
+//
+// The error model and the `Status` message can be used in a variety of
+// environments, either with or without APIs, to provide a
+// consistent developer experience across different environments.
+//
+// Example uses of this error model include:
+//
+// - Partial errors. If a service needs to return partial errors to the client,
+//     it may embed the `Status` in the normal response to indicate the partial
+//     errors.
+//
+// - Workflow errors. A typical workflow has multiple steps. Each step may
+//     have a `Status` message for error reporting.
+//
+// - Batch operations. If a client uses batch request and batch response, the
+//     `Status` message should be used directly inside batch response, one for
+//     each error sub-response.
+//
+// - Asynchronous operations. If an API call embeds asynchronous operation
+//     results in its response, the status of those operations should be
+//     represented directly using the `Status` message.
+//
+// - Logging. If some API errors are stored in logs, the message `Status` could
+//     be used directly after any stripping needed for security/privacy reasons.
+message Status {
+  // The status code, which should be an enum value of [google.rpc.Code][google.rpc.Code].
+  int32 code = 1;
+
+  // A developer-facing error message, which should be in English. Any
+  // user-facing error message should be localized and sent in the
+  // [google.rpc.Status.details][google.rpc.Status.details] field, or localized by the client.
+  string message = 2;
+
+  // A list of messages that carry the error details.  There is a common set of
+  // message types for APIs to use.
+  repeated google.protobuf.Any details = 3;
+}
diff --git a/buildstream/_protos/google/rpc/status_pb2.py b/buildstream/_protos/google/rpc/status_pb2.py
new file mode 100644
index 000000000..6c4772311
--- /dev/null
+++ b/buildstream/_protos/google/rpc/status_pb2.py
@@ -0,0 +1,88 @@
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: google/rpc/status.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+from google.protobuf import descriptor_pb2
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+from google.protobuf import any_pb2 as google_dot_protobuf_dot_any__pb2
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='google/rpc/status.proto',
+  package='google.rpc',
+  syntax='proto3',
+  serialized_pb=_b('\n\x17google/rpc/status.proto\x12\ngoogle.rpc\x1a\x19google/protobuf/any.proto\"N\n\x06Status\x12\x0c\n\x04\x63ode\x18\x01 \x01(\x05\x12\x0f\n\x07message\x18\x02 \x01(\t\x12%\n\x07\x64\x65tails\x18\x03 \x03(\x0b\x32\x14.google.protobuf.AnyB^\n\x0e\x63om.google.rpcB\x0bStatusProtoP\x01Z7google.golang.org/genproto/googleapis/rpc/status;status\xa2\x02\x03RPCb\x06proto3')
+  ,
+  dependencies=[google_dot_protobuf_dot_any__pb2.DESCRIPTOR,])
+
+
+
+
+_STATUS = _descriptor.Descriptor(
+  name='Status',
+  full_name='google.rpc.Status',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='code', full_name='google.rpc.Status.code', index=0,
+      number=1, type=5, cpp_type=1, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='message', full_name='google.rpc.Status.message', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='details', full_name='google.rpc.Status.details', index=2,
+      number=3, type=11, cpp_type=10, label=3,
+      has_default_value=False, default_value=[],
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  syntax='proto3',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=66,
+  serialized_end=144,
+)
+
+_STATUS.fields_by_name['details'].message_type = google_dot_protobuf_dot_any__pb2._ANY
+DESCRIPTOR.message_types_by_name['Status'] = _STATUS
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+Status = _reflection.GeneratedProtocolMessageType('Status', (_message.Message,), dict(
+  DESCRIPTOR = _STATUS,
+  __module__ = 'google.rpc.status_pb2'
+  # @@protoc_insertion_point(class_scope:google.rpc.Status)
+  ))
+_sym_db.RegisterMessage(Status)
+
+
+DESCRIPTOR.has_options = True
+DESCRIPTOR._options = _descriptor._ParseOptions(descriptor_pb2.FileOptions(), _b('\n\016com.google.rpcB\013StatusProtoP\001Z7google.golang.org/genproto/googleapis/rpc/status;status\242\002\003RPC'))
+# @@protoc_insertion_point(module_scope)
diff --git a/buildstream/_protos/google/rpc/status_pb2_grpc.py b/buildstream/_protos/google/rpc/status_pb2_grpc.py
new file mode 100644
index 000000000..a89435267
--- /dev/null
+++ b/buildstream/_protos/google/rpc/status_pb2_grpc.py
@@ -0,0 +1,3 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+import grpc
+