Add script to archive old roll branches

machenbach/archive/archive_branches.py

Index: machenbach/archive/archive_branches.py
diff --git a/machenbach/archive/archive_branches.py b/machenbach/archive/archive_branches.py
new file mode 100755
index 0000000000000000000000000000000000000000..c2c1c2a0475e77d35e0b6cd3c58932a89c9d3b45
--- /dev/null
+++ b/machenbach/archive/archive_branches.py
@@ -0,0 +1,87 @@
+#!/usr/bin/env python
+
+import os
+import re
+import subprocess
+import sys
+import time
+
+"""Script to archive heads under ignore/foo.
+
+This adds the refs passed to the script as parents to ignore/foo and on
+success deletes them.
+
+Assumes push merge access to ignore/foo and force push access to the branches.
+
+Assumes a workdir checkout with all required refs fetched.
+
+archive_branches.py path/to/checkout ref1 [ref2 ...]
+"""
+
+
+assert len(sys.argv) > 1
+
+
+def git(*args, **kwargs):
+  stdin_data = None
+  stdin_handle = None
+  if kwargs.get('stdin'):
+    stdin_data = kwargs.pop('stdin')
+    stdin_handle = subprocess.PIPE
+  proc = subprocess.Popen(('git',) + args,
+                          stdout=subprocess.PIPE,
+                          stderr=subprocess.STDOUT,
+                          stdin=stdin_handle,
+                          **kwargs)
+  output, _ = proc.communicate(stdin_data)
+  assert proc.returncode == 0, output.strip()
+  return output.strip()
+
+
+def synthesize(refs):
+  commits = []
+  for ref in refs:
+    commits.append(git('rev-parse', ref))
+
+  name = git('config', 'user.name')
+  email = git('config', 'user.email')
+
+  # Hardcoded the tree object of the ignore/foo README file.
+  data = ['tree c9c91bce52cd3003b6a9b0b4ae29d46210c40d51']
+  for commit in commits:
+    data.append('parent %s' % commit)
+
+  timestamp = int(time.time())
+  data.append('author %s <%s> %s +0000' % (name, email, timestamp))
+  data.append('committer %s <%s> %s +0000' % (name, email, timestamp))
+  data.append('')
+
+  # We don't really care about the commit message.
+  data.append('Placeholder commit\n')
+  data.append('Refs merged:\n' + '\n  '.join(refs) + '\n')
+
+  return git('hash-object', '-t', 'commit', '-w', '--stdin',
+             stdin='\n'.join(data))
+
+
+assert os.path.exists(sys.argv[1])
+os.chdir(sys.argv[1])
+
+refs = sys.argv[2:]
+assert refs, 'Provide at least one ref'
+
+# Make sure we only archive roll branches.
+for ref in refs:
+  assert re.match(r'\d*\.\d*\.\d*', ref)
+
+# Merge into ignore/foo.
+git('fetch', 'origin', 'refs/heads/ignore/foo')
+merge = synthesize(['FETCH_HEAD'] + refs)
+git('push', 'origin', '%s:refs/heads/ignore/foo' % merge)
+
+# Delete refs.
+del_specs = (
+    ['push', 'origin', '--force'] +
+    [':refs/heads/%s' % ref for ref in refs]
+)
+git(*del_specs)