Add explicit fetch flag for 'bst workspace-open'

2 files changed, 21 insertions, 14 deletions

diff --git a/buildstream/_frontend/cli.py b/buildstream/_frontend/cli.py
index 79f001690..b73771165 100644
--- a/buildstream/_frontend/cli.py
+++ b/buildstream/_frontend/cli.py
@@ -694,8 +694,10 @@ def workspace():
 @click.argument('element',
                 type=click.Path(readable=False))
 @click.argument('directory', type=click.Path(file_okay=False))
+@click.option('--fetch', 'fetch_', default=False, is_flag=True,
+              help="Enable auto-fetching of element and related junction(s)")
 @click.pass_obj
-def workspace_open(app, no_checkout, force, track_, element, directory):
+def workspace_open(app, no_checkout, force, track_, element, directory, fetch_):
     """Open a workspace for manual source modification"""
 
     if os.path.exists(directory):
@@ -712,7 +714,8 @@ def workspace_open(app, no_checkout, force, track_, element, directory):
         app.stream.workspace_open(element, directory,
                                   no_checkout=no_checkout,
                                   track_first=track_,
-                                  force=force)
+                                  force=force,
+                                  fetch=fetch_)
 
 
 ##################################################################
diff --git a/buildstream/_stream.py b/buildstream/_stream.py
index 019ce66f1..14398b90d 100644
--- a/buildstream/_stream.py
+++ b/buildstream/_stream.py
@@ -454,11 +454,13 @@ class Stream():
     #    no_checkout (bool): Whether to skip checking out the source
     #    track_first (bool): Whether to track and fetch first
     #    force (bool): Whether to ignore contents in an existing directory
+    #    fetch (bool): Enable auto-fetching of target and related junction(s)
     #
     def workspace_open(self, target, directory, *,
                        no_checkout,
                        track_first,
-                       force):
+                       force,
+                       fetch):
 
         if track_first:
             track_targets = (target,)
@@ -467,7 +469,8 @@ class Stream():
 
         elements, track_elements = self._load((target,), track_targets,
                                               selection=PipelineSelection.REDIRECT,
-                                              track_selection=PipelineSelection.REDIRECT)
+                                              track_selection=PipelineSelection.REDIRECT,
+                                              fetch_subprojects=fetch)
         target = elements[0]
         directory = os.path.abspath(directory)
 
@@ -487,20 +490,21 @@ class Stream():
             raise StreamError("Workspace '{}' is already defined at: {}"
                               .format(target.name, workspace.get_absolute_path()))
 
-        # If we're going to checkout, we need at least a fetch,
-        # if we were asked to track first, we're going to fetch anyway.
-        #
-        if not no_checkout or track_first:
+        # If we're going to checkout, we need to handle fetchs and tracks
+        if not no_checkout:
             track_elements = []
             if track_first:
                 track_elements = elements
-            self._fetch(elements, track_elements=track_elements)
 
-        if not no_checkout and target._get_consistency() != Consistency.CACHED:
-            raise StreamError("Could not stage uncached source. " +
-                              "Use `--track` to track and " +
-                              "fetch the latest version of the " +
-                              "source.")
+            fetch_elements = []
+            if fetch:
+                fetch_elements = elements
+
+            self._fetch(fetch_elements, track_elements=track_elements)
+            # _fetch above might have done only fetch, only track, both or
+            # none. We still need to ensure that element's refrenced sources
+            # are available.
+            self._pipeline.assert_sources_cached(elements)
 
         if workspace:
             workspaces.delete_workspace(target._get_full_name())