fabfile_part.py

# pip install redis
import redis
QUEUE="scale:sclgrp:up"
LOCK_KEY="scale:sclgrp:lock"
INCRD_KEY="scale:sclgrp:incrd"
def scaleout():
    r = redis.StrictRedis()
    queue_count=r.llen(QUEUE)
    locked=r.get(LOCK_KEY)
    print locked
    if queue_count > 0 and locked:
        print "scaleout in progress"
    if queue_count > 0 and not locked:
        r.set(LOCK_KEY,0)
        num=r.get(INCRD_KEY)
        incrd=num if num else 0
        setup_idcf_vm("scale_%(num)s"%{'num':incrd})
        r.delete(QUEUE,0)
        r.delete(LOCK_KEY,0)
        r.incr(INCRD_KEY)