Add support for YAML default config loading

4 files changed, 24 insertions, 16 deletions

diff --git a/buildstream/_elementfactory.py b/buildstream/_elementfactory.py
index cd3c2755d..deaa13c5e 100644
--- a/buildstream/_elementfactory.py
+++ b/buildstream/_elementfactory.py
@@ -58,5 +58,5 @@ class ElementFactory(PluginContext):
     #    LoadError (if the element itself took issue with the config)
     #
     def create(self, kind, context, project, artifacts, meta):
-        element_type = self.lookup(kind)
-        return element_type(context, project, artifacts, meta)
+        element_type, default_config = self.lookup(kind)
+        return element_type(context, project, artifacts, meta, default_config)
diff --git a/buildstream/_plugincontext.py b/buildstream/_plugincontext.py
index 8c208af48..96ee2e2c5 100644
--- a/buildstream/_plugincontext.py
+++ b/buildstream/_plugincontext.py
@@ -75,6 +75,7 @@ class PluginContext():
 
         if kind not in self.types:
             source = None
+            defaults = None
             dist, package = self.split_name(kind)
 
             if dist:
@@ -88,6 +89,13 @@ class PluginContext():
                     plugin.module_name.replace('.', os.sep) + '.py'
                 )
 
+                # Also load the defaults - required since setuptools
+                # may need to extract the file.
+                defaults = plugin.dist.get_resource_filename(
+                    pkg_resources._manager,
+                    plugin.module_name.replace('.', os.sep) + '.yaml'
+                )
+
                 # Set the plugin-base source to the setuptools directory
                 source = self.plugin_base.make_plugin_source(searchpath=[os.path.dirname(location)])
 
@@ -97,15 +105,21 @@ class PluginContext():
             if not source:
                 raise PluginError("No {} type registered for kind '{}'"
                                   .format(self.base_type.__name__, kind))
-            self.types[kind] = self.load_plugin(source, package)
+            self.types[kind] = self.load_plugin(source, package, defaults)
 
         return self.types[kind]
 
-    def load_plugin(self, source, kind):
+    def load_plugin(self, source, kind, defaults):
 
         try:
             plugin = source.load_plugin(kind)
 
+            if not defaults:
+                plugin_file = inspect.getfile(plugin)
+                plugin_dir = os.path.dirname(plugin_file)
+                plugin_conf_name = "{}.yaml".format(kind)
+                defaults = os.path.join(plugin_dir, plugin_conf_name)
+
         except ImportError as e:
             raise PluginError("Failed to load {} plugin '{}': {}"
                               .format(self.base_type.__name__, kind, e)) from e
@@ -121,7 +135,7 @@ class PluginContext():
 
         self.assert_plugin(kind, plugin_type)
         self.assert_version(kind, plugin_type)
-        return plugin_type
+        return (plugin_type, defaults)
 
     def split_name(self, name):
         if name.count(':') > 1:
diff --git a/buildstream/_sourcefactory.py b/buildstream/_sourcefactory.py
index 78fb7ec5f..3461ed2ff 100644
--- a/buildstream/_sourcefactory.py
+++ b/buildstream/_sourcefactory.py
@@ -59,5 +59,5 @@ class SourceFactory(PluginContext):
     #    LoadError (if the source itself took issue with the config)
     #
     def create(self, kind, context, project, meta):
-        source_type = self.lookup(kind)
+        source_type, _ = self.lookup(kind)
         return source_type(context, project, meta)
diff --git a/buildstream/element.py b/buildstream/element.py
index 9476cf3d6..7029acd7e 100644
--- a/buildstream/element.py
+++ b/buildstream/element.py
@@ -108,7 +108,7 @@ class Element(Plugin):
     any of the dependencies have changed.
     """
 
-    def __init__(self, context, project, artifacts, meta):
+    def __init__(self, context, project, artifacts, meta, plugin_conf):
 
         super().__init__(meta.name, context, project, meta.provenance, "element")
 
@@ -141,7 +141,7 @@ class Element(Plugin):
         self.__splits = None
 
         # Ensure we have loaded this class's defaults
-        self.__init_defaults()
+        self.__init_defaults(plugin_conf)
 
         # Collect the composited variables and resolve them
         variables = self.__extract_variables(meta)
@@ -1442,22 +1442,16 @@ class Element(Plugin):
         element_public['bst'] = element_bst
         defaults['public'] = element_public
 
-    def __init_defaults(self):
+    def __init_defaults(self, plugin_conf):
 
         # Defaults are loaded once per class and then reused
         #
         if not self.__defaults_set:
 
-            # Get the yaml file in the same directory as the plugin
-            plugin_file = inspect.getfile(type(self))
-            plugin_dir = os.path.dirname(plugin_file)
-            plugin_conf_name = "{}.yaml".format(self.get_kind())
-            plugin_conf = os.path.join(plugin_dir, plugin_conf_name)
-
             # Load the plugin's accompanying .yaml file if one was provided
             defaults = {}
             try:
-                defaults = _yaml.load(plugin_conf, plugin_conf_name)
+                defaults = _yaml.load(plugin_conf, os.path.basename(plugin_conf))
             except LoadError as e:
                 if e.reason != LoadErrorReason.MISSING_FILE:
                     raise e