Update CONFGIT mirror more robustly

The sequence of git operations suggested by Daniel Silverstone.

1 files changed, 23 insertions, 3 deletions

diff --git a/lorrycontroller/readconf.py b/lorrycontroller/readconf.py
index d060067..4aa3161 100644
--- a/lorrycontroller/readconf.py
+++ b/lorrycontroller/readconf.py
@@ -101,7 +101,7 @@ class ReadConfiguration(lorrycontroller.LorryControllerRoute):
             if not os.path.exists(confdir):
                 self.git_clone_confgit(confdir)
             else:
-                self.git_pull_confgit(confdir)
+                self.update_confgit(confdir)
 
     def git_clone_confgit(self, confdir):
         url = self.app_settings['confgit-url']
@@ -109,9 +109,29 @@ class ReadConfiguration(lorrycontroller.LorryControllerRoute):
         logging.info('Cloning %s to %s', url, confdir)
         cliapp.runcmd(['git', 'clone', '-b', branch, url, confdir])
 
-    def git_pull_confgit(self, confdir):
+    def update_confgit(self, confdir):
         logging.info('Updating CONFGIT in %s', confdir)
-        cliapp.runcmd(['git', 'pull'], cwd=confdir)
+
+        # The following sequence makes the working tree mirror
+        # current upstream git repository as closely as possible.
+
+        # Get rid of any local changes. No human is meant to edit
+        # anything locally, but there may be remnants of failed
+        # runs.
+        cliapp.runcmd(['git', 'reset', '--hard'], cwd=confdir)
+
+        # Get rid of any files not known by git. This might be,
+        # say, core dumps.
+        cliapp.runcmd(['git', 'clean', '-fdx'], cwd=confdir)
+
+        # Fetch updates to remote branches.
+        cliapp.runcmd(['git', 'remote', 'update', 'origin'], cwd=confdir)
+
+        # Now move the current HEAD to wherever the remote master
+        # branch is, no questions asked. This doesn't do merging
+        # or any of the other things we don't want in this situation.
+        cliapp.runcmd(
+            ['git', 'reset', '--hard', 'origin/master'], cwd=confdir)
 
     @property
     def config_file_name(self):