puppet_compiler_submodule

diff --git a/puppet_compiler/prepare.py b/puppet_compiler/prepare.py
index 6a61b21..7548c78 100644
--- a/puppet_compiler/prepare.py
+++ b/puppet_compiler/prepare.py
@@ -2,6 +2,7 @@ from contextlib import contextmanager
 import json
 import subprocess
 import os
+import re
 import shutil
 import requests
 from puppet_compiler import _log
@@ -128,20 +129,63 @@ class ManageCode(object):
         json_data = change.text.split("\n")[-2:][0]
         res = json.loads(json_data)
         revision = res["revisions"].values()[0]["_number"]
+        project = res["project"]
         ref = 'refs/changes/%02d/%d/%d' % (
             self.change_id % 100,
             self.change_id,
             revision)
         _log.debug(
-            'Downloading patch for change %d, revision %d',
-            self.change_id, revision)
-        git.fetch('-q', 'https://gerrit.wikimedia.org/r/operations/puppet',
-                  ref)
-        git.checkout('FETCH_HEAD')
-        git.pull('--rebase', 'origin', 'production')
+            'Downloading patch for project %s, change %d, revision %d',
+            project, self.change_id, revision)
+
+        # Assumption:
+        # Gerrit suported repo names and branches:
+        # 1) operations/puppet - origin/production
+        # 2) operations/puppet/submodulename - origin/master
+        if project == 'operations/puppet':
+            _pull_gerrit_revision(project, ref, 'production')
+        else:
+            _log.debug('The change has not been filed for the main puppet repo.\
+                Checking submodule repository matching the regex operations/puppet/(\w*)')
+            submodule_name = _get_submodule_name(project)
+            if submodule_name:
+                submodule_path = 'modules/' + submodule_name
+                _log.debug('Submodule repository name: %s path: %s',
+                    submodule_name, submodule_path)
+                base_repo_dir = os.getcwd
+                if os.path.exists(base_repo_dir + '/' + submodule_path):
+                    _log.debug('Change directory to: %s',
+                        base_repo_dir + '/' + submodule_path_)
+                    os.chdir(base_repo_dir + '/' + submodule_path)
+                    _pull_gerrit_revision(project, ref, 'master')
+                    _log.debug('Change directory to: %s', base_repo_dir)
+                    os.chdir(base_repo_dir)
+                else:
+                    _log.debug('Cannot access the submodule directory: %s',
+                        base_repo_dir + '/' + submodule_path)
+                    return
+            else:
+                _log.debug('No gerrit repository found!')
+                return
+
         # Update submodules according to the last hash of the parent repo.
+        _log.debug('Running submodule init')
         git.submodule('update', '--init')
 
+
+    def _get_submodule_name(project):
+        submodule_matcher = re.search('operations/puppet/(\w*)', project)
+        if submodule_matcher:
+            return submodule_matcher.group(1)
+        return None
+
+
+    def _pull_gerrit_revision(project, revision, origin_branch):
+        git.fetch('-q', 'https://gerrit.wikimedia.org/r/' + project, revision)
+        git.checkout('FETCH_HEAD')
+        git.pull('--rebase', 'origin', origin_branch)
+
+
     def _sh(command):
         try:
             subprocess.check_call(command, shell=True)