Add a queue cleaner that will clean selected queues only

This script can be useful to run when a large number of
messages are backlogged and we do not want to go in and
delete the full mnesia database but only want to selectively
clear off certain queues.

Change-Id: I0ecdeea3f4079c90ce9bc0bb31b2b4f0f55c313b

rabbit/rabbit_queue_cleaner.py

@@ -0,0 +1,157 @@
+#!/usr/bin/env python
+
+"""
+This script can help clear out selected rabbitmq queues and helps to
+ensure that *only* transient queues are cleared (vs notifications queues
+which should not be cleared due to side-effects this causes when those
+queues are cleared).
+"""
+
+from __future__ import print_function
+
+import argparse
+import os
+import subprocess
+import sys
+
+# Taken from a *liberty* capture of the output of `rabbitmqctl list_queues`
+QUEUE_ROOTS = tuple([
+    ('cells.intercell.broadcast', True),
+    ('cells.intercell.response', True),
+    ('cells.intercell.targeted', True),
+    ('cells.', True),
+    ('cells_fanout', True),
+    ('cert', False),
+    ('cinder-backup', False),
+    ('cinder-scheduler', False),
+    ('compute', False),
+    ('conductor', False),
+    ('console', False),
+    ('consoleauth', False),
+    ('dhcp_agent', False),
+    ('engine', False),
+    ('heat-engine-listener', False),
+    ('l3_agent', False),
+    ('q-agent-notifier-dvr-update', False),
+    ('q-agent-notifier-network-update', False),
+    ('q-agent-notifier-port-delete', False),
+    ('q-agent-notifier-port-update', False),
+    ('q-agent-notifier-security_group-update', False),
+    ('q-agent-notifier-tunnel-delete', False),
+    ('q-agent-notifier-tunnel-update', False),
+    ('q-l3-plugin', False),
+    ('q-plugin', False),
+    # All reply queues should be ok to purge as they will either
+    # just timeout or retry (or that's the desired goal).
+    ('reply_', True),
+    ('scheduler', False),
+])
+
+# Most queues get either '${root}_fanout.*' related queues or
+# '${root}.some_uuid' or '${root}.some_hostname' formats so these will
+# capture all of those as these will be appended to the root and will
+# match if they are a prefix of a queue name.
+AUTO_PREFIX_SUFFIXES = tuple(["_fanout", "."])
+
+
+def prompt_for_purge(queue_count):
+    input = ""
+    while input == "":
+        input = raw_input("Purge %s queues? " % (queue_count))
+        input = input.lower().strip()
+        if input not in ('yes', 'no', 'y', 'n'):
+            print("Please enter one of 'yes' or 'no'")
+            input = ""
+        else:
+            if input in ['yes', 'y']:
+                return True
+            else:
+                return False
+
+
+def should_purge_queue(queue_name, size):
+    for r, is_prefix in QUEUE_ROOTS:
+        if r == queue_name:
+            # Don't delete the roots themselves...
+            return False
+        # Otherwise check if we should try a bunch of prefix or just
+        # check the prefix itself...
+        if is_prefix and queue_name.startswith(r):
+            return True
+        else:
+            for prefix_suffix in AUTO_PREFIX_SUFFIXES:
+                if queue_name.startswith(r + prefix_suffix):
+                    return True
+    return False
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("-d", "--dry_run",
+                        action='store_true', default=False,
+                        help="simulate purge commands but do not"
+                             " actually run them")
+    parser.add_argument("-e", "--ensure_gone",
+                        action='append', default=[],
+                        help="ensure named queue is purged",
+                        metavar="queue")
+    parser.add_argument("-n", "--no_prompt",
+                        action='store_true', default=False,
+                        help="skip being prompted before purging")
+    parser.add_argument("-u", "--username",
+                        help=("purge via a connection"
+                              " using given username (default=%(default)s)"),
+                        default='guest')
+    parser.add_argument("-p", "--password",
+                        help=("purge via a connection using"
+                              " given password (default=%(default)s)"),
+                        default='guest')
+    args = parser.parse_args()
+    if os.getuid() != 0:
+        # We can't run rabbitmqctl or rabbitmqadmin without root
+        # so make sure we have it...
+        print("This program must be ran as root!", file=sys.stderr)
+        sys.exit(1)
+    # This tries to get the list queues output and then parses it to
+    # try to figure out why queues we should try to clear, this is not
+    # a formal (sadly it appears there is none) so this may break
+    # at some point in the future...
+    stdout = subprocess.check_output(['rabbitmqctl', 'list_queues'])
+    # The first line is expected to be 'Listing queues ...'
+    lines = stdout.splitlines()
+    first_line = lines[0]
+    if first_line != "Listing queues ...":
+        print("First line of the output of `rabbitmqctl list_queues`"
+              " was not as expected, avoiding further damage by exiting"
+              " early!", file=sys.stderr)
+        sys.exit(1)
+    goodbye_queues = []
+    queues = sorted(lines[1:])
+    if queues:
+        print("There are %s queues..." % (len(queues)))
+        for i, line in enumerate(queues):
+            queue_name, str_size = line.split()
+            if (queue_name in args.ensure_gone
+                    or should_purge_queue(queue_name, int(str_size))):
+                print("%s. %s (purging)" % (i + 1, queue_name))
+                goodbye_queues.append(queue_name)
+            else:
+                print("%s. %s (not purging)" % (i + 1, queue_name))
+    if not args.dry_run and goodbye_queues:
+        if not args.no_prompt:
+            if not prompt_for_purge(len(goodbye_queues)):
+                sys.exit(0)
+        print("Executing %s purges, please wait..." % (len(goodbye_queues)))
+        for queue_name in goodbye_queues:
+            purge_cmd = [
+                'rabbitmqadmin', 'purge', 'queue', 'name=%s' % queue_name,
+            ]
+            if args.username:
+                purge_cmd.extend(['-u', args.username])
+            if args.password:
+                purge_cmd.extend(['-p', args.password])
+            subprocess.check_output(purge_cmd)
+
+
+if __name__ == '__main__':
+    main()