Adds a reviews expire cron script

This script:
1. abandon all open reviews with no activity for 2 weeks
2. abandon all negative reviews with no activity for 1 week

Fixes bug 907842

Change-Id: I2cccab46e0f6ffd8b1cc5e8227556f31dc963705

gerrit/expire_old_reviews.py

@@ -0,0 +1,75 @@
+#!/usr/bin/env python
+# Copyright (c) 2012 OpenStack, LLC.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+# This script is designed to expire old code reviews that have not been touched
+# using the following rules:
+# 1. if open and no activity in 2 weeks, expire
+# 2. if negative comment and no activity in 1 week, expire
+
+import os
+import paramiko
+import json
+import logging
+
+GERRIT_USER = os.environ.get('GERRIT_USER', 'launchpadsync')
+GERRIT_SSH_KEY = os.environ.get('GERRIT_SSH_KEY',
+                                 '/home/gerrit2/.ssh/launchpadsync_rsa')
+
+logging.basicConfig(format='%(asctime)-6s: %(name)s - %(levelname)s - %(message)s', filename='/var/log/gerrit/expire_reviews.log')
+logger= logging.getLogger('expire_reviews')
+logger.setLevel(logging.INFO)
+
+logger.info('Starting expire reviews')
+logger.info('Connecting to Gerrit')
+
+ssh = paramiko.SSHClient()
+ssh.load_system_host_keys(GERRIT_SSH_KEY)
+ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
+ssh.connect('localhost', username=GERRIT_USER, port=29418)
+
+def expire_patch_set(patch_id, patch_subject, has_negative):
+  if has_negative:
+    message= 'code review expired after 1 week of no activity after a negative review'
+  else:
+    message= 'code review expired after 2 weeks of no activity'
+  command='gerrit review --abandon --message="{0}" {1}'.format(message, patch_id)
+  logger.info('Expiring: %s - %s: %s', patch_id, patch_subject, message)
+  stdin, stdout, stderr = ssh.exec_command(command)
+  if stdout.channel.recv_exit_status() != 0:
+    logger.error(stderr.read())
+
+# Query all open with no activity for 2 weeks
+logger.info('Searching no activity for 2 weeks')
+stdin, stdout, stderr = ssh.exec_command('gerrit query --current-patch-set --format JSON status:open age:2w')
+
+for line in stdout:
+  row= json.loads(line)
+  if not row.has_key('rowCount'):
+    expire_patch_set(row['currentPatchSet']['revision'], row['subject'], False)
+
+# Query all reviewed with no activity for 1 week
+logger.info('Searching no activity on negative review for 1 week')
+stdin, stdout, stderr = ssh.exec_command('gerrit query --current-patch-set --all-approvals --format JSON status:reviewed age:1w')
+
+for line in stdout:
+  row= json.loads(line)
+  if not row.has_key('rowCount'):
+    # Search for negative approvals
+    for approval in row['currentPatchSet']['approvals']:
+      if approval['value'] == '-1':
+        expire_patch_set(row['currentPatchSet']['revision'], row['subject'], True)
+        break
+
+logger.info('End expire review')