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     notify(notice[0], '\n'.join(notice))
  47
  48
  49 def processMessage(message):
  50     '''Unpack the data we want from an SQS message.'''
  51     try:
  52         data = json.loads(json.loads(message.body)['Message'])
  53         event = data['Event']
  54         ASGName = data['AutoScalingGroupName']
  55         InstanceId = data['EC2InstanceId']
  56     except:
  57         logging.debug('unparsable message %r', message.body)
  58         message.delete()
  59     else:
  60         if event == 'autoscaling:EC2_INSTANCE_LAUNCH':
  61             try:
  62                 instanceState = ec2r.Instance(InstanceId).state['Name']
  63             except:
  64                 logging.debug('instance %s does not exist', InstanceId)
  65                 message.change_visibility(VisibilityTimeout=60 * 2)
  66             else:
  67                 if instanceState == 'running':
  68                     handleEvent(message, event, ASGName, InstanceId)
  69                 else:
  70                     logging.debug('instance %s is in state %s, will try again', InstanceId, instanceState)
  71                     message.change_visibility(VisibilityTimeout=60 * 2)
  72         else:
  73             logging.debug('nothing to do for event %r', data)
  74             message.delete()
  75
  76
  77 class PidFileSingleton:
  78     '''Ensure that only one instance of this specific script runs at once.'''
  79     def __init__(self):
  80         self.pidfile = os.path.join(gettempdir(), sha256(os.path.abspath(sys.argv[0])).hexdigest() + '.pid')
  81         try:
  82             fd = os.open(self.pidfile, os.O_WRONLY|os.O_CREAT|os.O_EXCL, )
  83         except OSError as e:
  84             self.pidfile = None
  85             if e.errno == errno.EEXIST:
  86                 logging.debug('An instance of this is already running.')
  87                 sys.exit(0)
  88             raise e
  89         with os.fdopen(fd, 'w') as f:
  90             f.write(str(os.getpid()))
  91     def __del__(self):
  92         if self.pidfile:
  93             os.unlink(self.pidfile)
  94
  95
  96 parser = argparse.ArgumentParser(description='act on SQS Notifications')
  97 parser.add_argument('--profile', metavar='PROFILE', dest='profile_name', help='AWS Profile (default: current IAM Role)')
  98 parser.add_argument('--region', metavar='REGION', dest='region_name', help='AWS Region')
  99 parser.add_argument('playbooks', metavar='directory', help='path containing playbooks et al')
 100 parser.add_argument('queue', help='SQS Queue')
 101 parser.add_argument('arn', nargs='?', default=None, help='ARN of SNS topic')
 102 args = parser.parse_args()
 103
 104 pidfile = PidFileSingleton()
 105
 106 session = boto3.session.Session(**{k:v for k,v in vars(args).items() if k in ('profile_name', 'region_name')})
 107 queue = session.resource('sqs').get_queue_by_name(QueueName=args.queue)
 108 topic = session.resource('sns').Topic(args.arn) if args.arn else None
 109 ec2r = session.resource('ec2')
 110
 111 while True:
 112     # long poll until there are no more messages
 113     messages = queue.receive_messages(MaxNumberOfMessages=10, WaitTimeSeconds=20)
 114     if not len(messages):
 115         break
 116     for message in messages:
 117         processMessage(message)