_artifactcache/casserver.py: Implement Capabilities service

1 files changed, 24 insertions, 0 deletions

diff --git a/buildstream/_artifactcache/casserver.py b/buildstream/_artifactcache/casserver.py
index 0af65729b..f89421d88 100644
--- a/buildstream/_artifactcache/casserver.py
+++ b/buildstream/_artifactcache/casserver.py
@@ -38,6 +38,10 @@ from .._context import Context
 from .cascache import CASCache
 
 
+# The default limit for gRPC messages is 4 MiB
+_MAX_BATCH_TOTAL_SIZE_BYTES = 4 * 1024 * 1024
+
+
 # Trying to push an artifact that is too large
 class ArtifactTooLargeException(Exception):
     pass
@@ -67,6 +71,9 @@ def create_server(repo, *, enable_push):
     remote_execution_pb2_grpc.add_ContentAddressableStorageServicer_to_server(
         _ContentAddressableStorageServicer(artifactcache), server)
 
+    remote_execution_pb2_grpc.add_CapabilitiesServicer_to_server(
+        _CapabilitiesServicer(), server)
+
     buildstream_pb2_grpc.add_ReferenceStorageServicer_to_server(
         _ReferenceStorageServicer(artifactcache, enable_push=enable_push), server)
 
@@ -230,6 +237,23 @@ class _ContentAddressableStorageServicer(remote_execution_pb2_grpc.ContentAddres
         return response
 
 
+class _CapabilitiesServicer(remote_execution_pb2_grpc.CapabilitiesServicer):
+    def GetCapabilities(self, request, context):
+        response = remote_execution_pb2.ServerCapabilities()
+
+        cache_capabilities = response.cache_capabilities
+        cache_capabilities.digest_function.append(remote_execution_pb2.SHA256)
+        cache_capabilities.action_cache_update_capabilities.update_enabled = False
+        cache_capabilities.max_batch_total_size_bytes = _MAX_BATCH_TOTAL_SIZE_BYTES
+        cache_capabilities.symlink_absolute_path_strategy = remote_execution_pb2.CacheCapabilities.ALLOWED
+
+        response.deprecated_api_version.major = 2
+        response.low_api_version.major = 2
+        response.high_api_version.major = 2
+
+        return response
+
+
 class _ReferenceStorageServicer(buildstream_pb2_grpc.ReferenceStorageServicer):
     def __init__(self, cas, *, enable_push):
         super().__init__()