Add cli main & user conf option for 'cache-buildtrees' context

_context.py: Add cache_buildtrees global user context, the default
of which is set to by default to 'always' via the addition of
cache-buildtrees to userconfig.yaml cache group. 'failure' & 'never'
can be given as valid options.

app.py & cli.py: Add --cache-buildtrees as a bst main option, which
when passed with a valid option can override the default or user
defined context for cache_buildtrees.

tests/completions/completions.py: Update for the added flag.

5 files changed, 24 insertions, 2 deletions

diff --git a/buildstream/_context.py b/buildstream/_context.py
index 9c53e7d75..6fe7c3f52 100644
--- a/buildstream/_context.py
+++ b/buildstream/_context.py
@@ -121,6 +121,9 @@ class Context():
         # Whether or not to attempt to pull build trees globally
         self.pull_buildtrees = None
 
+        # Whether or not to cache build trees on artifact creation
+        self.cache_buildtrees = None
+
         # Boolean, whether we double-check with the user that they meant to
         # close the workspace when they're using it to access the project.
         self.prompt_workspace_close_project_inaccessible = None
@@ -201,7 +204,7 @@ class Context():
         # our artifactdir - the artifactdir may not have been created
         # yet.
         cache = _yaml.node_get(defaults, Mapping, 'cache')
-        _yaml.node_validate(cache, ['quota', 'pull-buildtrees'])
+        _yaml.node_validate(cache, ['quota', 'pull-buildtrees', 'cache-buildtrees'])
 
         self.config_cache_quota = _yaml.node_get(cache, str, 'quota')
 
@@ -213,6 +216,10 @@ class Context():
         # Load pull build trees configuration
         self.pull_buildtrees = _yaml.node_get(cache, bool, 'pull-buildtrees')
 
+        # Load cache build trees configuration
+        self.cache_buildtrees = _node_get_option_str(
+            cache, 'cache-buildtrees', ['always', 'failure', 'never'])
+
         # Load logging config
         logging = _yaml.node_get(defaults, Mapping, 'logging')
         _yaml.node_validate(logging, [
diff --git a/buildstream/_frontend/app.py b/buildstream/_frontend/app.py
index b6da079bd..329f9a2c6 100644
--- a/buildstream/_frontend/app.py
+++ b/buildstream/_frontend/app.py
@@ -183,7 +183,8 @@ class App():
             'builders': 'sched_builders',
             'pushers': 'sched_pushers',
             'network_retries': 'sched_network_retries',
-            'pull_buildtrees': 'pull_buildtrees'
+            'pull_buildtrees': 'pull_buildtrees',
+            'cache_buildtrees': 'cache_buildtrees'
         }
         for cli_option, context_attr in override_map.items():
             option_value = self._main_options.get(cli_option)
diff --git a/buildstream/_frontend/cli.py b/buildstream/_frontend/cli.py
index e3c5059b9..c4dd91c75 100644
--- a/buildstream/_frontend/cli.py
+++ b/buildstream/_frontend/cli.py
@@ -251,6 +251,9 @@ def print_version(ctx, param, value):
               help="The mirror to fetch from first, before attempting other mirrors")
 @click.option('--pull-buildtrees', is_flag=True, default=None,
               help="Include an element's build tree when pulling remote element artifacts")
+@click.option('--cache-buildtrees', default=None,
+              type=click.Choice(['always', 'failure', 'never']),
+              help="Cache artifact build tree content on creation")
 @click.pass_context
 def cli(context, **kwargs):
     """Build and manipulate BuildStream projects
diff --git a/buildstream/data/userconfig.yaml b/buildstream/data/userconfig.yaml
index 0834b93f6..0b4535cea 100644
--- a/buildstream/data/userconfig.yaml
+++ b/buildstream/data/userconfig.yaml
@@ -41,6 +41,15 @@ cache:
   # Whether to pull build trees when downloading element artifacts
   pull-buildtrees: False
 
+  # Whether to cache build trees on artifact creation:
+  #
+  #  always - Always cache artifact build tree content
+  #  failure - Only cache build trees of failed builds
+  #  never - Don't cache artifact build tree content
+  #
+  cache-buildtrees: always
+
+
 #
 #    Scheduler
 #
diff --git a/tests/frontend/completions.py b/tests/frontend/completions.py
index cb151c284..c374df2a0 100644
--- a/tests/frontend/completions.py
+++ b/tests/frontend/completions.py
@@ -23,6 +23,7 @@ MAIN_OPTIONS = [
     "--builders ",
     "-c ",
     "-C ",
+    "--cache-buildtrees ",
     "--colors ",
     "--config ",
     "--debug ",
@@ -156,6 +157,7 @@ def test_options(cli, cmd, word_idx, expected):
 
 @pytest.mark.parametrize("cmd,word_idx,expected", [
     ('bst --on-error ', 2, ['continue ', 'quit ', 'terminate ']),
+    ('bst --cache-buildtrees ', 2, ['always ', 'failure ', 'never ']),
     ('bst show --deps ', 3, ['all ', 'build ', 'none ', 'plan ', 'run ']),
     ('bst show --deps=', 2, ['all ', 'build ', 'none ', 'plan ', 'run ']),
     ('bst show --deps b', 3, ['build ']),