Merge "Allow jobs to disable all services"

Author: Zuul

roles/write-devstack-local-conf/README.rst

@@ -53,7 +53,12 @@ Write the local.conf file for use by devstack
    A dictionary mapping service names to boolean values.  If the
    boolean value is ``false``, a ``disable_service`` line will be
    emitted for the service name.  If it is ``true``, then
-   ``enable_service`` will be emitted.  All other values are ignored.
+   ``enable_service`` will be emitted. All other values are ignored.
+   The special key ``base`` can be used to enable or disable the base set of
+   services enabled by default. If ``base`` is found, it will processed before
+   all other keys. If its value is ``False`` a ``disable_all_services`` will be
+   emitted; if its value is ``True`` nothing will be emitted since base
+   services are enabled by default.
 
 .. zuul:rolevar:: devstack_plugins
    :type: dict

roles/write-devstack-local-conf/library/devstack_local_conf.py

@@ -124,6 +124,9 @@ def handle_plugins(self, plugins):
                 self.localrc.append('enable_plugin {} {}'.format(k, v))
 
     def handle_services(self, services):
+        base_services = services.pop('base', True)
+        if not base_services:
+            self.localrc.append('disable_all_services')
         for k, v in services.items():
             if v is False:
                 self.localrc.append('disable_service {}'.format(k))