compass/deploy/ansible/roles/ha/templates/failover.j2

   1 import ConfigParser, os, socket
   2 import logging as LOG
   3 import pxssh
   4 import sys
   5 import re
   6
   7 LOG_FILE="/var/log/mysql_failover"
   8 try:
   9     os.remove(LOG_FILE)
  10 except:
  11     pass
  12
  13 LOG.basicConfig(format='%(asctime)s %(message)s', datefmt='%m/%d/%Y %I:%M:%S %p', filename=LOG_FILE,level=LOG.DEBUG)
  14 ha_vip = {{ HA_VIP }}
  15 LOG.info("ha_vip: %s" % ha_vip)
  16
  17 #ha_vip = "10.1.0.50"
  18 galera_path = '/etc/mysql/conf.d/wsrep.cnf'
  19 pattern = re.compile(r"gcomm://(?P<prev_ip>.*)")
  20
  21 def ssh_get_hostname(ip):
  22     try:
  23         s = pxssh.pxssh()
  24         s.login("%s" % ip, "root", "root")
  25         s.sendline('hostname')   # run a command
  26         s.prompt()             # match the prompt
  27         result = s.before.strip()      # print everything before the prompt.
  28         return result.split(os.linesep)[1]
  29     except pxssh.ExceptionPxssh as e:
  30         LOG.error("pxssh failed on login.")
  31         raise
  32
  33 def failover(mode):
  34     config = ConfigParser.ConfigParser()
  35     config.optionxform = str
  36     config.readfp(open(galera_path))
  37     wsrep_cluster_address = config.get("mysqld", "wsrep_cluster_address")
  38     wsrep_cluster_address = pattern.match(wsrep_cluster_address).groupdict()["prev_ip"]
  39
  40     LOG.info("old wsrep_cluster_address = %s" % wsrep_cluster_address)
  41
  42     if mode == "master":
  43         # refresh wsrep_cluster_address to null
  44         LOG.info("I'm being master, set wsrep_cluster_address to null")
  45         wsrep_cluster_address = ""
  46
  47     elif mode == "backup":
  48         # refresh wsrep_cluster_address to master int ip
  49         hostname = ssh_get_hostname(ha_vip)
  50         wsrep_cluster_address = socket.gethostbyname(hostname)
  51         LOG.info("I'm being slave, set wsrep_cluster_address to master internal ip")
  52
  53     LOG.info("new wsrep_cluster_address = %s" % wsrep_cluster_address)
  54     wsrep_cluster_address  = "gcomm://%s" % wsrep_cluster_address
  55     config.set("mysqld", "wsrep_cluster_address", wsrep_cluster_address)
  56     with open(galera_path, 'wb') as fp:
  57         #config.write(sys.stdout)
  58         config.write(fp)
  59
  60     os.system("service mysql restart")
  61     LOG.info("failover success!!!")
  62
  63 if __name__ == "__main__":
  64     LOG.debug("call me: %s" % sys.argv)
  65     failover(sys.argv[1])