Python script that allows to run commands in the host from inside a Vagrant container using SSH

runonhost

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

from os import getcwd
from json import loads
from sys import argv, stdout
from shlex import split as shsplit
from os.path import expanduser, isfile, relpath, join
from subprocess import check_output, CalledProcessError, Popen, PIPE


def main():

    # Determine arguments
    arguments = ' '.join(argv[1:])
    if not arguments:
        print(
            'ERROR: No command given'
        )
        exit(1)

    # Read host information
    infofile = expanduser('~/.hostinfo.json')
    if not isfile(infofile):
        print(
            'ERROR: Host info file not found: {}'.format(infofile)
        )
        exit(1)

    with open(infofile) as fd:
        hostinfo = loads(fd.read())

    user = hostinfo.get('user')
    root = hostinfo.get('root')
    if user is None or root is None:
        print(
            'ERROR: Missing data in host info file: {}'.format(infofile)
        )
        exit(1)

    # Determine host ip
    try:
        cmd_ip = 'ip route | awk \'/default/ { print $3 }\''
        host = check_output(
            cmd_ip, shell=True
        ).decode('utf-8').strip()
    except CalledProcessError:
        print('ERROR: Unable to determine host IP address')
        exit(1)

    # Determine repository root
    try:
        cmd_git = 'git rev-parse --show-toplevel'
        repo_root = check_output(
            shsplit(cmd_git)
        ).decode('utf-8').strip()
    except CalledProcessError:
        print('ERROR: Unable to determine git root directory')
        exit(1)

    # Determine relative path from repository root
    subdir = relpath(getcwd(), repo_root)
    chdir = 'cd {} && '.format(join(root, subdir))

    # Execute command
    cmd = 'ssh -A -t {user}@{host} "{chdir}{arguments}"'.format(**locals())
    print('=> Executing:')
    print(cmd)

    process = Popen(shsplit(cmd), stdout=PIPE, stderr=PIPE)
    while True:
        out = process.stdout.read(1)
        if out != b'':
            stdout.buffer.write(out)
            stdout.flush()
        elif process.poll() is not None:
            break

    exit(process.poll())


if __name__ == '__main__':
    main()