cmd-virt-install

#!/usr/bin/env python3

# "install" a coreos system with libvirt.  This code in the future
# ideally gets added to `virt-install`.  See also https://github.com/coreos/fedora-coreos-tracker/issues/235
# It is inspired by https://coreos.com/os/docs/latest/booting-with-libvirt.html

import argparse
import subprocess
import json
import os
import re
import sys
import random
import string
import tempfile

import libvirt

cosa_dir = os.path.dirname(os.path.abspath(__file__))
sys.path.insert(0, cosa_dir)

from cosalib import cmdlib
from cosalib.builds import Builds

# Parse args and dispatch
parser = argparse.ArgumentParser()
parser.add_argument("--connect", "-c", help="libvirt URI", default="qemu:///system")
parser.add_argument("--ignition", "-i", help="Ignition config", required=True)
parser.add_argument("--build", help="Build ID")
parser.add_argument("--image", help="Image path")
parser.add_argument("--pool", help="Storage pool", default="default")
parser.add_argument("--name", help="Prefix for libvirt resources")
parser.add_argument("--instid", help="Suffix appended to libvirt resources")
parser.add_argument("--console", action='store_true',
                    help="Connect to serial console after install")
args, vinstall_args = parser.parse_known_args()

if args.image:
    qemupath = args.image
    if args.name is None:
        args.name = os.path.basename(qemupath)
else:
    builds = Builds()
    if args.build is None:
        args.build = builds.get_latest()
    builddir = builds.get_build_dir(args.build)
    with open(os.path.join(builddir, "meta.json")) as f:
        buildmeta = json.load(f)
    qemuimg = buildmeta.get('images', {}).get('qemu')
    if qemuimg is None:
        raise SystemExit(f"No qemu image in build: {args.build}")
    qemupath = os.path.join(builddir, qemuimg['path'])

    if args.name is None:
        args.name = buildmeta['name']

if args.instid is None:
    args.instid = ''.join([random.choice(string.ascii_letters + string.digits) for n in range(8)])

ignvol = f"{args.name}-ign-{args.instid}"
ignsize = os.path.getsize(args.ignition)

vconn = libvirt.open(args.connect)
if vconn is None:
    raise Exception('Failed to connect to libvirt "{}"'.format(args.connect))

basevolname = os.path.basename(qemupath)


def virsh(*vargs):
    subprocess.check_call(['virsh', '-c', args.connect] + list(vargs))


pool = vconn.storagePoolLookupByName(args.pool)


def get_pool_path(connect, pool):
    poolxml = subprocess.check_output(['virsh', '-c', connect, 'pool-dumpxml', pool], encoding='UTF-8')
    r = re.compile(re.escape("<path>") + "(.*)" + re.escape("</path>"))
    for line in poolxml.split():
        m = r.search(line)
        if not m:
            continue
        return m.group(1)
    raise Exception(f"Failed to find path for pool: {pool}")


poolpath = get_pool_path(args.connect, args.pool)

qemu_size = str(json.loads(subprocess.check_output(['qemu-img', 'info', '--output=json', qemupath]))['virtual-size'])

if basevolname not in pool.listVolumes():
    print(f"Uploading: {basevolname}")
    virsh('vol-create-as', args.pool, basevolname, qemu_size, '--format=qcow2')
    if qemupath.endswith('.gz'):
        with tempfile.NamedTemporaryFile(prefix='cosa-libvrun', dir='/var/tmp') as t:
            with open(qemupath) as inf:
                subprocess.check_call(['gunzip'], stdin=inf, stdout=t)
        virsh('vol-upload', f'--pool={args.pool}', basevolname, t.name)
    else:
        virsh('vol-upload', f'--pool={args.pool}', basevolname, qemupath)
volname = f"{args.name}-{args.instid}"
virsh('vol-create-as', args.pool, volname, qemu_size, '--format=qcow2', f'--backing-vol={basevolname}',
      '--backing-vol-format=qcow2')

with tempfile.NamedTemporaryFile(prefix='cosa-libvrun') as t:
    # Create the volume via XML to make the mode 0644, so that it's readable
    # by qemu.
    t.write(f"""<volume type='file'>
  <name>{ignvol}</name>
  <capacity unit='bytes'>{ignsize}</capacity>
  <target>
    <format type='raw'/>
    <permissions>
      <mode>0644</mode>
    </permissions>
  </target>
</volume>""".encode('UTF-8'))
    t.flush()
    virsh('vol-create', args.pool, t.name)
virsh('vol-upload', f'--pool={args.pool}', ignvol, args.ignition)

domname = f"{args.name}-{args.instid}"
qemu_args = " ".join(['-fw_cfg', f'name=opt/com.coreos/config,file={poolpath}/{ignvol}'])
basevinstall_args = ['virt-install', f"--connect={args.connect}",
                     '--import', f'--disk=source.pool={args.pool},source.volume={volname}',
                     '--tpm', 'emulator',
                     f'--name={domname}', '--os-variant=rhel8-unknown',
                     f'--qemu-commandline={qemu_args}',
                     '--noautoconsole']
cmdlib.runcmd(basevinstall_args + vinstall_args)
if args.console:
    os.execlp("virsh", "virsh", "console", domname)