Support for multiple override files

To use multiple override files run --template-override f1
--template-override f2.
One caveat is it won't work well if both modify same variable/block. One
will override another, so if both overrides tries to add pkg to horizon
tpl, only second package gets installed

Change-Id: I8d2937c2dad83d3ec94efa6d9c9849a922c0cef6

2 files changed, 17 insertions, 5 deletions

diff --git a/kolla/common/config.py b/kolla/common/config.py
index 8be553b10..c2d8a5e0a 100755
--- a/kolla/common/config.py
+++ b/kolla/common/config.py
@@ -203,8 +203,8 @@ _CLI_OPTS = [
                 help=("Don't build images. Generate Dockerfile only")),
     cfg.IntOpt('timeout', default=120,
                help='Time in seconds after which any operation times out'),
-    cfg.StrOpt('template-override',
-               help='Path to template override file'),
+    cfg.MultiOpt('template-override', types.String(),
+                 help='Path to template override file'),
     cfg.StrOpt('logs-dir', help='Path to logs directory'),
     cfg.BoolOpt('pull', default=True,
                 help='Attempt to pull a newer version of the base image.'),
diff --git a/kolla/image/build.py b/kolla/image/build.py
index 35029f198..c2f6fe614 100755
--- a/kolla/image/build.py
+++ b/kolla/image/build.py
@@ -661,11 +661,11 @@ class KollaWorker(object):
 
             template = env.get_template(tpl_path)
             if self.conf.template_override:
-                template_path = os.path.dirname(self.conf.template_override)
-                template_name = os.path.basename(self.conf.template_override)
+                tpl_dict = self._merge_overrides(self.conf.template_override)
+                template_name = os.path.basename(tpl_dict.keys()[0])
                 values['parent_template'] = template
                 env = jinja2.Environment(  # nosec: not used to render HTML
-                    loader=jinja2.FileSystemLoader(template_path))
+                    loader=jinja2.DictLoader(tpl_dict))
                 env.filters.update(self._get_filters())
                 env.globals.update(self._get_methods())
                 template = env.get_template(template_name)
@@ -677,6 +677,18 @@ class KollaWorker(object):
                 f.write(content)
                 LOG.debug("Wrote it to %s", content_path)
 
+    def _merge_overrides(self, overrides):
+        tpl_name = os.path.basename(overrides[0])
+        with open(overrides[0], 'r') as f:
+            tpl_content = f.read()
+        for override in overrides[1:]:
+            with open(override, 'r') as f:
+                cont = f.read()
+            # Remove extends header
+            cont = re.sub(r'.*\{\%.*extends.*\n', '', cont)
+            tpl_content += cont
+        return {tpl_name: tpl_content}
+
     def find_dockerfiles(self):
         """Recursive search for Dockerfiles in the working directory"""
         self.docker_build_paths = list()