Get Elasticsearch index name from alias

get_index.py

#! /usr/bin/python2
#
# aux script to read elasticsearch aliases info and return real index name for given alias
#
# written for use with https://github.com/mallocator/Elasticsearch-Exporter which
# does not seem to work with aliases
#
# 2015, DECK36 GmbH & Co. KG, <martin.schuette@deck36.de>

import json
import sys

if len(sys.argv) != 2:
    print "Read Elasticsearch /_aliases/ output and return real index name for given alias"
    print "Usage: give alias name as command-line parameter, pipe JSON to stdin"
    print ""
    print "Example: curl -s localhost:9200/_aliases/ | get_index.py myalias"
    sys.exit(1)

alias = sys.argv[1]
a = json.loads(sys.stdin.read())
l = [x for x in a if a[x]["aliases"].has_key(alias)]
if len(l) == 1:
    print l[0]
    sys.exit(0)
# else: print alias name
if a.has_key(alias):
    print alias
    sys.exit(0)
# else:
sys.exit(1)