_stream: Don't require runtime deps when building with --deps none

doc/source/using_config.rst

@@ -381,6 +381,7 @@ Attributes
   values for this attribute are:
 
   * ``none``: Only build elements required to generate the expected target artifacts
+  * ``run``: Build required elements and their their runtime dependencies
   * ``all``: Build elements even if they are build dependencies of artifacts which are already cached
 
 

src/buildstream/_context.py

@@ -465,10 +465,10 @@ def load(self, config: Optional[str] = None) -> None:
         self.build_retry_failed = build.get_bool("retry-failed")
 
         dependencies = build.get_str("dependencies")
-        if dependencies not in ["none", "all"]:
+        if dependencies not in ["none", "run", "all"]:
             provenance = build.get_scalar("dependencies").get_provenance()
             raise LoadError(
-                "{}: Invalid value for 'dependencies'. Choose 'none' or 'all'.".format(provenance),
+                "{}: Invalid value for 'dependencies'. Choose 'none', 'run', or 'all'.".format(provenance),
                 LoadErrorReason.INVALID_DATA,
             )
         self.build_dependencies = _PipelineSelection(dependencies)

src/buildstream/_stream.py

@@ -1766,7 +1766,7 @@ def _load(
             # rely on state changes during processing to determine which elements
             # must be processed.
             #
-            if selection == _PipelineSelection.NONE:
+            if selection in (_PipelineSelection.NONE, _PipelineSelection.RUN):
                 required_elements = elements
             elif selection == _PipelineSelection.BUILD:
                 required_elements = list(_pipeline.dependencies(elements, _Scope.BUILD, recurse=False))
@@ -1775,8 +1775,13 @@ def _load(
         if not required_elements:
             required_elements = selected
 
+        if selection == _PipelineSelection.NONE:
+            scope = _Scope.NONE
+        else:
+            scope = _Scope.RUN
+
         for element in required_elements:
-            element._set_required()
+            element._set_required(scope)
 
         return selected
 

src/buildstream/data/userconfig.yaml

@@ -93,7 +93,7 @@ build:
   #
   # Control which dependencies to build
   #
-  dependencies: none
+  dependencies: run
 
 
 #