marathon-es-hosts.py

#!/usr/bin/python

# Retrieves a comma-delimited list of unicasts hosts for Elasticsearch instances
# running on marathon, based on the application name.

import sys, getopt, json, requests

def exit_invalid_args():
  print 'usage: marathon-es-hosts.py -m <marathon_url> -a <app_name>'
  sys.exit(2)

def main(argv):
  marathon_url = ''
  app_name = ''
  try:
    opts, args = getopt.getopt(argv,"m:a:",["marathon=","app="])
  except getopt.GetoptError:
    exit_invalid_args()
  
  for opt, arg in opts:
    if opt in ("-m", "--marathon"):
       marathon_url = arg
    elif opt in ("-a", "--app"):
       app_name = arg
  
  if not marathon_url or not app_name:
     exit_invalid_args()

  resp = requests.get(url="{0}/v2/apps/{1}".format(marathon_url, app_name))
  data = json.loads(resp.text)

  unicast_hosts = []

  for task in data['app']['tasks']:
    # get the host name and the second exposed port (this should be the transport port)
    unicast_hosts.append("{0}:{1}".format(task['host'], task['ports'][1]))

  print ",".join(unicast_hosts)

if __name__ == "__main__":
   main(sys.argv[1:])