#!/usr/bin/env python
"""
    MongoDB Replication Lag
    ~~~~~~~~~~~~~~~~~~~~~~~

    Connects to a single mongo instance and retrieve
    replication lag for all connected members.

    munin-node.conf:
    [mongodb_lag]
    env.host 127.0.0.1
    env.port 27017

    :author: Stefan Andersen <stefan@stefanandersen.dk>
    :license: The Beer Ware License (Revision 42)
              <stefan@stefanandersen.dk> wrote this file. As long 
              as you retain this notice you can do whatever you want 
              with this stuff. If we meet some day, and you think 
              this stuff is worth it, you can buy me a beer in return. 
"""
import os
import sys
import pymongo

def _get_members():
    host = os.environ.get('host', '127.0.0.1')
    port = os.environ.get('port', 27017)
    conn = pymongo.MongoClient(host,port)
    repl_status = conn.admin.command("replSetGetStatus")

    members = {}
    for member in repl_status['members']:
        if member['stateStr'] != 'ARBITER' :
            name = member['name'].split('.')[0]
            members[name] = {'state': member['state'], 'optimeDate': member['optimeDate']}
    return members

def run():
    members = _get_members();
    for member in members:
        if members[member]['state'] == 1:
            primary_optime = members[member]['optimeDate']

    for member in members:
        lag = (primary_optime - members[member]['optimeDate']).seconds
        print "{0}.value {1}".format(member, lag)

def config():
    print """graph_title MongoDB replication lag
graph_args --base 1000
graph_vlabel Replication lag (seconds)
graph_category db
"""
   
    for member in _get_members():
        print "{0}.label {0}".format(member)

if __name__ == "__main__":
    if len(sys.argv) > 1 and sys.argv[1] == "config":
        config()
    else:
        run()