Add test config grammar for per app overlay ppa.

In some circumstances we want to install packages from overlay PPA
on specific applications and not across the whole model.

Add configuration grammar, actual implementation of generic setup
step will follow in subsequent patch.

Signed-off-by: Frode Nordahl <[email protected]>

zaza/utilities/deployment_env.py

@@ -85,7 +85,7 @@ def parse_option_list_string(option_list, delimiter=None):
     return settings
 
 
-def get_overlay_ppas(model_alias='default_alias'):
+def get_overlay_ppas(model_alias='default_alias', application=None):
     """Get overlay_ppas from global_config.
 
     In the config file for the tests, the tests_options.overlay_ppa option
@@ -95,20 +95,38 @@ def get_overlay_ppas(model_alias='default_alias'):
     Please refer to docstring of parse_overlay_ppa function for more
     information.
 
+    When application is provided, additional grammar to constrain the
+    overlay PPA to specific applications is supported, for example:
+
+        overlay_ppas:
+            myapp:
+              - ppa:mylpuser/myppa
+            myotherapp:
+              - source: fakesource
+                key: fakekey
+
     :param model_alias: Name of model alias, defaults to 'default_alias'.
     :type model_alias: Option[str]
+    :param application: Name of application to retrieve config for.
+    :type application: Option[str]
     :returns: List of overlay PPAs.
     :rtype: Option[List[Any]]
     """
     config = zaza.global_options.get_options()
+    config_overlay_ppas = None
     try:
-        return config[model_alias].overlay_ppas
+        config_overlay_ppas = config[model_alias].overlay_ppas
     except KeyError:
         try:
-            return config.overlay_ppas
+            config_overlay_ppas = config.overlay_ppas
         except KeyError:
             pass
-    return None
+    if config_overlay_ppas and application:
+        return [overlay_ppa
+                for overlay_ppa in config_overlay_ppas
+                if (isinstance(overlay_ppa, dict) and
+                    application in overlay_ppa)] or None
+    return config_overlay_ppas
 
 
 def _parse_overlay_ppa_v1(overlay_ppa):