generate_keepalived

#!/usr/bin/python

# This script scans the haproxy configuration and generates the keepalived config to match.
# Used in HA deployments where we need fail-over capability.

# First developed: Hereward Cooper - Apr 2011

import subprocess
import re
import datetime
import imp
import sys
from subprocess import Popen, PIPE, STDOUT

__author__ = "Hereward Cooper <coops@fawk.eu>"
__version__ = "v0.1"
__website__ = "http://github.com/hcooper/haproxy-tools/"


def get_ips(configfile):

    """
    Extract the IPs which HAProxy will listen on (i.e. VIPs) from the config file
    """

    # This could be ported to pure python, however I can't figure the regex out.
    getips = subprocess.Popen(["egrep '(listen|frontend)' " + configfile + "\
            | grep -o '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}' \
            | grep -v 127.0.0.1 \
            | sort \
            | uniq"], shell=True, stdin=PIPE, stdout=PIPE, stderr=STDOUT, close_fds=True)

    # Return the list of VIPs
    return getips.stdout.read()


def main(vips):

    """
    Generate the keepalived config using the list of VIPs we're provided
    """

    # Get current time
    time = datetime.datetime.now()
    
    ## Import the sysconfig configuration file
    config = imp.load_source('haproxy', '/etc/sysconfig/haproxy')
    
    ## Check the haproxy slave config
    try:
    	config.HAPROXYSLAVE
    except:
    	ROLE="slave"
    	PRIORITY="100"
    else:
    	ROLE="master"
    	PRIORITY="101"
    
    ## Check the interface where the VIPs live is defined
    try:
    	config.VIPINT
    except:
    	print "ERROR: No interface defined in /etc/sysconfig/haproxy"
    	sys.exit(1)
    else:
    	VIPINT = config.VIPINT
    
    OUTPUT = """
    ## /etc/keepalived/keepalived.conf
    ## THIS CONFIGURATION IS AUTOMATICALLY GENERATED.
    ## MANUAL CHANGES WILL BE OVERWRITTEN.
    ##
    ## Configuration at """ + str(time.ctime()) + """
    ## ROLE = """ + ROLE + """
    ## VIPINT = """ + VIPINT + """
    
    vrrp_script chk_haproxy {               # Requires keepalived-1.1.13
            script "killall -0 haproxy"     # cheaper than pidof
            interval 2                      # check every 2 seconds
            weight 2                        # add 2 points of prio if OK
    }
    
    vrrp_instance VI_1 {
            interface """ + VIPINT + """
            state MASTER
            virtual_router_id 51
            priority """ + PRIORITY + """			# 101=master, 100=standby
            virtual_ipaddress {
    		""" + vips + """
            }
            track_script {
                chk_haproxy
            }
    }
    """
    return OUTPUT
    
    
if __name__ == "__main__":

    haproxy_config="/etc/haproxy/haproxy.cfg"

    # Fire up the engines
    vips = get_ips(haproxy_config)
    print main(vips)