git.squeep.com Git - awsible/blob - sqs-action.py

   1 #!/usr/bin/env python
   2 '''\
   3 Check an SQS queue for ASG lifecycle notifications of new instances,
   4 and run the appropriate Ansible playbook against the host.
   5 '''
   6
   7 import argparse
   8 import logging
   9 import boto3
  10 import json
  11 import sys
  12 import os
  13 import errno
  14 from subprocess import Popen, PIPE
  15 from tempfile import gettempdir
  16 from hashlib import sha256
  17
  18
  19 ANSIBLE_PLAYBOOK_CMD = '/usr/local/bin/ansible-playbook'
  20
  21
  22 def notify(subj, msg):
  23     if topic:
  24         u8msg = unicode(msg).encode('utf-8')
  25         topic.publish(Subject=subj, Message=u8msg[:262144])
  26     else:
  27         print(msg)
  28
  29
  30 def handleEvent(message, event, ASGName, InstanceId):
  31     notice = [' '.join([ASGName, InstanceId, event])]
  32     if os.path.isfile(os.path.join(args.playbooks, ASGName + '.yml')):
  33         message.change_visibility(VisibilityTimeout=(60 * 15)) # hope config doesn't take more than 15m
  34         cmd = [ ANSIBLE_PLAYBOOK_CMD, '-i', 'inventory', '--limit', InstanceId, ASGName + '.yml']
  35         p = Popen(cmd, cwd=args.playbooks, stdout=PIPE, stderr=PIPE)
  36         (stdoutdata, stderrdata) = p.communicate()
  37         retval = p.returncode
  38         message.change_visibility(VisibilityTimeout=60)
  39         if retval:
  40             notice += ['FAILURE CODE {}'.format(retval), stderrdata, stdoutdata]
  41         else:
  42             notice += ['SUCCESS']
  43             message.delete()
  44     else:
  45         notice += ['no action taken: no playbook for this ASG']
  46         message.delete()
  47     notify(notice[0], '\n'.join(notice))
  48
  49
  50 def processMessage(message):
  51     '''Unpack the data we want from an SQS message.'''
  52     try:
  53         data = json.loads(json.loads(message.body)['Message'])
  54         event = data['Event']
  55         ASGName = data['AutoScalingGroupName']
  56         InstanceId = data['EC2InstanceId']
  57     except:
  58         logging.debug('unparsable message %r', message.body)
  59         message.delete()
  60     else:
  61         if event == 'autoscaling:EC2_INSTANCE_LAUNCH':
  62             try:
  63                 instanceState = ec2r.Instance(InstanceId).state['Name']
  64             except:
  65                 logging.debug('instance %s does not exist', InstanceId)
  66                 message.change_visibility(VisibilityTimeout=60 * 2)
  67             else:
  68                 if instanceState == 'running':
  69                     handleEvent(message, event, ASGName, InstanceId)
  70                 else:
  71                     logging.debug('instance %s is in state %s, will try again', InstanceId, instanceState)
  72                     message.change_visibility(VisibilityTimeout=60 * 2)
  73         else:
  74             logging.debug('nothing to do for event %r', data)
  75             message.delete()
  76
  77
  78 class PidFileSingleton:
  79     '''Ensure that only one instance of this specific script runs at once.'''
  80     def __init__(self):
  81         self.pidfile = os.path.join(gettempdir(), sha256(os.path.abspath(sys.argv[0])).hexdigest() + '.pid')
  82         try:
  83             fd = os.open(self.pidfile, os.O_WRONLY|os.O_CREAT|os.O_EXCL, )
  84         except OSError as e:
  85             self.pidfile = None
  86             if e.errno == errno.EEXIST:
  87                 logging.debug('An instance of this is already running.')
  88                 sys.exit(0)
  89             raise e
  90         with os.fdopen(fd, 'w') as f:
  91             f.write(str(os.getpid()))
  92     def __del__(self):
  93         if self.pidfile:
  94             os.unlink(self.pidfile)
  95
  96
  97 parser = argparse.ArgumentParser(description='act on SQS Notifications')
  98 parser.add_argument('--profile', metavar='PROFILE', dest='profile_name', help='AWS Profile (default: current IAM Role)')
  99 parser.add_argument('--region', metavar='REGION', dest='region_name', help='AWS Region')
 100 parser.add_argument('playbooks', metavar='directory', help='path containing playbooks et al')
 101 parser.add_argument('queue', help='SQS Queue')
 102 parser.add_argument('arn', nargs='?', default=None, help='ARN of SNS topic')
 103 args = parser.parse_args()
 104
 105 pidfile = PidFileSingleton()
 106
 107 session = boto3.session.Session(**{k:v for k,v in vars(args).items() if k in ('profile_name', 'region_name')})
 108 queue = session.resource('sqs').get_queue_by_name(QueueName=args.queue)
 109 topic = session.resource('sns').Topic(args.arn) if args.arn else None
 110 ec2r = session.resource('ec2')
 111
 112 while True:
 113     # long poll until there are no more messages
 114     messages = queue.receive_messages(MaxNumberOfMessages=10, WaitTimeSeconds=20)
 115     if not len(messages):
 116         break
 117     for message in messages:
 118         processMessage(message)