lxc-host.py

#!/usr/bin/python
"""
Simple usage to log into a container via ssh

  $ lxc-host -s -n container_name

Simple usage to query the addresses of a container

  $ lxc-host -n container_name

Deps

  $ sudo apt-get install python-dnspython

"""
from __future__ import print_function

import argparse
import os
import sys
import subprocess

from dns import resolver


def setup_parser():
    parser = argparse.ArgumentParser()
    parser.add_argument(
        '-n', '--name', required=True,
        help='Name of container')
    parser.add_argument(
        '-d', '--dns', default="10.0.3.1",
        help='Dns Server')
    parser.add_argument(
        '-r', '--reset', dest="reset_fingerprint", action="store_true", default=False,
        help="Reset the ssh fingerprint for the container")
    parser.add_argument(
        '-s', '--ssh', action="store_true",
        help='SSH into resolved container address')
    parser.add_argument(
        '-u', '--user', default="ubuntu",
        help='User to ssh into container with.')
    parser.add_argument('params', nargs="*")
    return parser


def main():
    parser = setup_parser()
    options = parser.parse_args()

    dns_server = resolver.Resolver(configure=False)
    dns_server.nameservers = [options.dns]

    try:
        result = dns_server.query(options.name)
    except resolver.NoAnswer:
        print("Container not found", file=sys.stderr)
        sys.exit(15)

    for r in result.rrset:
        if options.reset_fingerprint:
            subprocess.check_call(["ssh-keygen", "-R", str(r)])
        if options.ssh:
            args = ["ssh", "-o", "StrictHostKeyChecking no",
             "%s@%s" % (options.user, str(r))]
            args.extend(options.params)
            return os.execvp("ssh", args)
        print(r)

if __name__ == '__main__':
    main()