Allow fetching plugins as part of the build

This change allows additional archives to be fetched as part of the
build and added to images.

An example use case is the installation of plugins for neutron. For
example, to add the networking-arista plugin to neutron-server, one
would do the following in kolla-build.conf:

[neutron-server-plugin-networking-arista]
type = url
location = http://tarballs.openstack.org/networking-arista/networking-arista-master.tar.gz

The format for plugin sections is <image-name>-plugin-<plugin-name>

The required Dockerfile additions will be added in the next patchset.

Background to this change:
https://review.openstack.org/#/c/207545/3/docker_templates/neutron/neutron-server/Dockerfile.j2

Related: blueprint neutron-third-party-plugins
DocImpact
Change-Id: Idec2ca9fd06163c7d820e8c4bc9ebca8d9673856

kolla/cmd/build.py

@@ -90,9 +90,8 @@ class WorkerThread(Thread):
                 break
             self.end_task(image)
 
-    def process_source(self, image):
-        source = image['source']
-        dest_archive = os.path.join(image['path'], image['name'] + '-archive')
+    def process_source(self, image, source):
+        dest_archive = os.path.join(image['path'], source['name'] + '-archive')
 
         if source.get('type') == 'url':
             LOG.debug("{}:Getting archive from {}".format(image['name'],
@@ -140,6 +139,8 @@ class WorkerThread(Thread):
         # Set time on destination archive to epoch 0
         os.utime(dest_archive, (0, 0))
 
+        return dest_archive
+
     def builder(self, image):
         LOG.debug('{}:Processing'.format(image['name']))
         if image['status'] == 'unmatched':
@@ -157,10 +158,27 @@ class WorkerThread(Thread):
         LOG.info('{}:Building'.format(image['name']))
 
         if 'source' in image and 'source' in image['source']:
-            self.process_source(image)
+            self.process_source(image, image['source'])
             if image['status'] == "error":
                 return
 
+        plugin_archives = list()
+        for plugin in image['plugins']:
+            archive_path = self.process_source(image, plugin)
+            if image['status'] == "error":
+                return
+            plugin_archives.append(archive_path)
+        if plugin_archives:
+            for plugin_archive in plugin_archives:
+                with tarfile.open(plugin_archive, 'r') as plugin_archive_tar:
+                    plugin_archive_tar.extractall(
+                        path=os.path.join(image['path'], 'plugins'))
+        else:
+            os.mkdir(os.path.join(image['path'], 'plugins'))
+        with tarfile.open(os.path.join(image['path'], 'plugins-archive'),
+                          'w') as tar:
+            tar.add(os.path.join(image['path'], 'plugins'), arcname='plugins')
+
         # Pull the latest image for the base distro only
         pull = True if image['parent'] is None else False
 
@@ -512,6 +530,21 @@ class KollaWorker(object):
                 self.image_statuses_unmatched)
 
     def build_image_list(self):
+        def process_source_installation(image, section):
+            installation = dict()
+            try:
+                installation['type'] = \
+                    self.source_location.get(section, 'type')
+                installation['source'] = \
+                    self.source_location.get(section, 'location')
+                installation['name'] = section
+                if installation['type'] == 'git':
+                    installation['reference'] = \
+                        self.source_location.get(section, 'reference')
+            except six.moves.configparser.NoSectionError:
+                LOG.debug('{}:No source location found'.format(section))
+            return installation
+
         for path in self.docker_build_paths:
             # Reading parent image name
             with open(os.path.join(path, 'Dockerfile')) as f:
@@ -527,23 +560,17 @@ class KollaWorker(object):
             if not image['parent_name'].startswith(self.namespace + '/'):
                 image['parent'] = None
             image['children'] = list()
+            image['plugins'] = list()
 
             if self.install_type == 'source':
-                image['source'] = dict()
-                try:
-                    image['source']['type'] = \
-                        self.source_location.get(image['name'], 'type')
-                    image['source']['source'] = \
-                        self.source_location.get(image['name'], 'location')
-                    if image['source']['type'] == 'git':
-                        image['source']['reference'] = \
-                            self.source_location.get(image['name'],
-                                                     'reference')
-
-                except six.moves.configparser.NoSectionError:
-                    LOG.debug('{}:No source location found'.format(
-                        image['name']))
-                    pass
+                image['source'] = \
+                    process_source_installation(image, image['name'])
+                for plugin in [match.group(0) for match in
+                               (re.search('{}-plugin-.+'.format(image['name']),
+                                          section) for section in
+                               self.source_location.sections()) if match]:
+                    image['plugins'].append(
+                        process_source_installation(image, plugin))
 
             self.images.append(image)