Script to rerun a test to catch a race condition

repro.py

import re
import subprocess
import os

small_before_re = re.compile("(\w+)  /tmp/small")
big_before_re   = re.compile("(\w+)  /tmp/big")
small_after_re  = re.compile("(\w+)  small")
big_after_re    = re.compile("(\w+)  big")

os.putenv("PACKER_LOG", "1")

while True:
    output = subprocess.check_output(["packer", "build", "docker-download.json"], stderr=subprocess.STDOUT)
    small_before = small_before_re.findall(output)[0]
    big_before   = big_before_re.findall(output)[0]
    small_after  = small_after_re.findall(output)[0]
    big_after    = big_after_re.findall(output)[0]

    print "small {0} {1}".format(small_before, small_after)
    print "big {0} {1}".format(big_before, big_after)

    if small_before != small_after:
        print output
        exit(1)

    if big_before != big_after:
        print output
        exit(1)