request-lb-weight.py

#!/usr/bin/env python

# Please note the LICENSE file accompanying this script.
# See https://github.com/reincubate/haproxy-dynamic-weight for more information.

import os
import socket
import site
import sys
import memcache

# If the calculation of the load AND the weighting/actioning
# of the load data is at the same interval (1 minute) then we
# will see a lot of jerkiness. So we take the 5 minute average.
# This means servers get lowered in priority more slowly.
load = os.getloadavg()[1]
hostname = socket.gethostname()
max_load = 5

if len(sys.argv) < 2:
    raise Exception(
        'You must pass the hostname and port of your memcached server')

# Weight must range from 1 - 256
if load < 0.001:
    load = 0.001
if load > max_load:
    load = max_load

weight = int(((255 / max_load) * ((max_load + 0.001) - load)) + 1)

if len(sys.argv) > 2:
    print('Declaring weight of %s for %s for %ss, given load of %s' %
          (weight, hostname, 60 * 2, load))

mc = memcache.Client([sys.argv[1]], )
mc.set('server-weight-%s' % hostname, weight,
       time=60 * 2)  # Set a two minute expiry