Helper script for creating LXC containers on Proxmox

lxc-create-ct.py

#!/usr/bin/env python3

import argparse
import os
import subprocess
import sys
import time


def execute_shell(cmd) -> str:
    """
    Executes cmd on shell and returns stdout output
    """
    sys.stderr.write('[shell] running: %s ..' % ' '.join(cmd))

    start = time.time()
    output = subprocess.check_output(cmd, encoding='utf-8').strip()
    took = time.time() - start

    sys.stderr.write('. took %.2f sec\n' % took)

    return output


def main():
    parser = argparse.ArgumentParser(description='Creates & bootstraps an LXC CT')
    parser.add_argument('--vmid', required=False, default=None, type=int, help='Override the vmid for the created CT (default: nextid)')
    parser.add_argument('--hostname', required=True, help='The vm hostname')
    parser.add_argument('--cores', default=2, type=int, help='Number of cores to assign')
    parser.add_argument('--memory', default=2048, type=int, help='Amount of RAM (in MB) to assign')
    parser.add_argument('--rootfs', required=True, help='The rootfs to create the CT on; e.g. local:16 creates the storage on local with 16 GB')
    parser.add_argument('--template', required=True, help='The fully qualified path to the OS template; e.g. local:vztmpl/ubuntu-18.04-standard_18.04-1_amd64.tar.gz')
    parser.add_argument('--features', default='mount=nfs', help='The features to enable on the CT (default: NFS)')
    parser.add_argument('--net0', default='name=eth0,bridge=vmbr0,ip=dhcp,ip6=auto,type=veth', help='The configuration for net0 (default: vmbr0 dhcp)')
    parser.add_argument('--root-pub-key', help='If provided, the path to the public key to store in root\'s authorized_keys file')
    parser.add_argument('--apt-upgrade', action='store_true', help='If enabled, runs apt update and apt upgrade to bring the base system up to date')

    args = parser.parse_args()
    
    if args.vmid:
        vmid = args.vmid
    else:
        vmid = execute_shell(['pvesh', 'get', '/cluster/nextid'])

    sys.stderr.write('creating ct with vmid: %s\n' % vmid)

    cmd_args = [
        'pct', 'create', vmid, args.template,
        '--hostname', args.hostname,
        '--cores', str(args.cores),
        '--memory', str(args.memory),
        '--features', args.features,
        '--rootfs', args.rootfs,
    ]

    if args.net0:
        cmd_args.extend(['--net0', args.net0])

    # Create the CT
    execute_shell(cmd_args)

    # Start the CT
    sys.stderr.write('starting ct %s\n' % vmid)
    execute_shell(['pct', 'start', vmid])

    if args.root_pub_key:
        if not os.path.exists(args.root_pub_key):
            sys.stderr.write('root pub key does not exist: %s\n' % args.root_pub_key)

        sys.stderr.write('installing root pub key from file: %s\n' % args.root_pub_key)

        execute_shell(['pct', 'exec', vmid, 'mkdir', '/root/.ssh'])
        execute_shell(['pct', 'exec', vmid, 'chmod', '700', '/root/.ssh'])
        execute_shell(['pct', 'push', vmid, args.root_pub_key, '/root/.ssh/authorized_keys'])
        execute_shell(['pct', 'exec', vmid, 'chmod', '600', '/root/.ssh/authorized_keys'])

    if args.apt_upgrade:
        sys.stderr.write('upgrading base system to latest pkgs with apt\n')
        execute_shell(['pct', 'exec', vmid, 'apt', 'update'])
        execute_shell(['pct', 'exec', vmid, '--', 'apt', 'upgrade', '-y'])
        execute_shell(['pct', 'exec', vmid, '--', 'shutdown', '-r', 'now'])

    return 1


if __name__ == '__main__':
    sys.exit(main())