update /etc/hosts with new hostname

update_etchosts.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import re
import logging

# imported from parent directory
import utils

LOG = logging.getLogger(__name__)

LOG.info("Init module %s", __name__)

def main():
    hostname = "localhost-{}".format(utils.random_string(6))

    out, err, ret = utils.cmd_run(['hostnamectl', 'set-hostname', hostname])
    if ret != 0:
        LOG.error("Failed to reset hostname(%d)", ret)
        LOG.error("DUMP: %s", out)
        return

    # Update /etc/hosts
    r1 = "127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4 {}".format(hostname)
    r2 = "::1         localhost localhost.localdomain localhost6 localhost6.localdomain6 {}".format(hostname)
    r3 = "127.0.1.1   {}".format(hostname)

    replace_ts = [
            (r"^127\.0\.0\.1.*$", r1),
            (r"^::1.*$", r2),
            (r"^127\.0\.1\.1.*$", r3),
        ]

    hosts = utils.read_file("/etc/hosts")

    for pattern, replace in replace_ts:
        hosts = re.sub(pattern, replace, hosts, flags=re.MULTILINE)

    LOG.info(hosts)

def run():
    main()

if __name__ == '__main__':
    main()