Re: [Qemu-devel] [PATCH v6 04/12] tests: Add vm test lib

["Alex Bennée" <alex.bennee@linaro.org>]

Fam Zheng <famz@redhat.com> writes:

> This is the common code to implement a "VM test" to
>
>   1) Download and initialize a pre-defined VM that has necessary
>   dependencies to build QEMU and SSH access.
>
>   2) Archive $SRC_PATH to a .tar file.
>
>   3) Boot the VM, and pass the source tar file to the guest.
>
>   4) SSH into the VM, untar the source tarball, build from the source.
>
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  tests/vm/basevm.py | 276 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 276 insertions(+)
>  create mode 100755 tests/vm/basevm.py
>
> diff --git a/tests/vm/basevm.py b/tests/vm/basevm.py
> new file mode 100755
> index 0000000000..9db91d61fa
> --- /dev/null
> +++ b/tests/vm/basevm.py
> @@ -0,0 +1,276 @@
> +#!/usr/bin/env python
> +#
> +# VM testing base class
> +#
> +# Copyright (C) 2017 Red Hat Inc.
> +#
> +# Authors:
> +#  Fam Zheng <famz@redhat.com>
> +#
> +# This work is licensed under the terms of the GNU GPL, version 2.  See
> +# the COPYING file in the top-level directory.
> +#
> +
> +import os
> +import sys
> +import logging
> +import time
> +import datetime
> +sys.path.append(os.path.join(os.path.dirname(__file__), "..", "..", "scripts"))
> +from qemu import QEMUMachine
> +import subprocess
> +import hashlib
> +import optparse
> +import atexit
> +import tempfile
> +import shutil
> +import multiprocessing
> +import traceback
> +
> +SSH_KEY = """\
> +-----BEGIN RSA PRIVATE KEY-----
> +MIIEowIBAAKCAQEAopAuOlmLV6LVHdFBj8/eeOwI9CqguIJPp7eAQSZvOiB4Ag/R
> +coEhl/RBbrV5Yc/SmSD4PTpJO/iM10RwliNjDb4a3I8q3sykRJu9c9PI/YsH8WN9
> ++NH2NjKPtJIcKTu287IM5JYxyB6nDoOzILbTyJ1TDR/xH6qYEfBAyiblggdjcvhA
> +RTf93QIn39F/xLypXvT1K2O9BJEsnJ8lEUvB2UXhKo/JTfSeZF8wPBeowaP9EONk
> +7b+nuJOWHGg68Ji6wVi62tjwl2Szch6lxIhZBpnV7QNRKMfYHP6eIyF4pusazzZq
> +Telsq6xI2ghecWLzb/MF5A+rklsGx2FNuJSAJwIDAQABAoIBAHHi4o/8VZNivz0x
> +cWXn8erzKV6tUoWQvW85Lj/2RiwJvSlsnYZDkx5af1CpEE2HA/pFT8PNRqsd+MWC
> +7AEy710cVsM4BYerBFYQaYxwzblaoojo88LSjVPw3h5Z0iLM8+IMVd36nwuc9dpE
> +R8TecMZ1+U4Tl6BgqkK+9xToZRdPKdjS8L5MoFhGN+xY0vRbbJbGaV9Q0IHxLBkB
> +rEBV7T1mUynneCHRUQlJQEwJmKpT8MH3IjsUXlG5YvnuuvcQJSNTaW2iDLxuOKp8
> +cxW8+qL88zpb1D5dppoIu6rlrugN0azSq70ruFJQPc/A8GQrDKoGgRQiagxNY3u+
> +vHZzXlECgYEA0dKO3gfkSxsDBb94sQwskMScqLhcKhztEa8kPxTx6Yqh+x8/scx3
> +XhJyOt669P8U1v8a/2Al+s81oZzzfQSzO1Q7gEwSrgBcRMSIoRBUw9uYcy02ngb/
> +j/ng3DGivfJztjjiSJwb46FHkJ2JR8mF2UisC6UMXk3NgFY/3vWQx78CgYEAxlcG
> +T3hfSWSmTgKRczMJuHQOX9ULfTBIqwP5VqkkkiavzigGRirzb5lgnmuTSPTpF0LB
> +XVPjR2M4q+7gzP0Dca3pocrvLEoxjwIKnCbYKnyyvnUoE9qHv4Kr+vDbgWpa2LXG
> +JbLmE7tgTCIp20jOPPT4xuDvlbzQZBJ5qCQSoZkCgYEAgrotSSihlCnAOFSTXbu4
> +CHp3IKe8xIBBNENq0eK61kcJpOxTQvOha3sSsJsU4JAM6+cFaxb8kseHIqonCj1j
> +bhOM/uJmwQJ4el/4wGDsbxriYOBKpyq1D38gGhDS1IW6kk3erl6VAb36WJ/OaGum
> +eTpN9vNeQWM4Jj2WjdNx4QECgYAwTdd6mU1TmZCrJRL5ZG+0nYc2rbMrnQvFoqUi
> +BvWiJovggHzur90zy73tNzPaq9Ls2FQxf5G1vCN8NCRJqEEjeYCR59OSDMu/EXc2
> +CnvQ9SevHOdS1oEDEjcCWZCMFzPi3XpRih1gptzQDe31uuiHjf3cqcGPzTlPdfRt
> +D8P92QKBgC4UaBvIRwREVJsdZzpIzm224Bpe8LOmA7DeTnjlT0b3lkGiBJ36/Q0p
> +VhYh/6cjX4/iuIs7gJbGon7B+YPB8scmOi3fj0+nkJAONue1mMfBNkba6qQTc6Y2
> +5mEKw2/O7/JpND7ucU3OK9plcw/qnrWDgHxl0Iz95+OzUIIagxne
> +-----END RSA PRIVATE KEY-----
> +"""
> +SSH_PUB_KEY = """\
> +ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCikC46WYtXotUd0UGPz9547Aj0KqC4gk+nt4BBJm86IHgCD9FygSGX9EFutXlhz9KZIPg9Okk7+IzXRHCWI2MNvhrcjyrezKREm71z08j9iwfxY3340fY2Mo+0khwpO7bzsgzkljHIHqcOg7MgttPInVMNH/EfqpgR8EDKJuWCB2Ny+EBFN/3dAiff0X/EvKle9PUrY70EkSycnyURS8HZReEqj8lN9J5kXzA8F6jBo/0Q42Ttv6e4k5YcaDrwmLrBWLra2PCXZLNyHqXEiFkGmdXtA1Eox9gc/p4jIXim6xrPNmpN6WyrrEjaCF5xYvNv8wXkD6uSWwbHYU24lIAn qemu-vm-key
> +"""

I'm not sure we should be embedding the keys in the script. I understand
we need a common key for downloaded images (although it would be better
to post-customise the image after download with the local developer
keys). Perhaps ./tests/testing-keys/id_rsa[.pub]?

> +
> +class BaseVM(object):
> +    GUEST_USER = "qemu"
> +    GUEST_PASS = "qemupass"
> +    ROOT_PASS = "qemupass"
> +
> +    # The script to run in the guest that builds QEMU
> +    BUILD_SCRIPT = ""
> +    # The guest name, to be overridden by subclasses
> +    name = "#base"
> +    def __init__(self, debug=False, vcpus=None):
> +        self._guest = None
> +        self._tmpdir = tempfile.mkdtemp(prefix="vm-test-", suffix=".tmp", dir=".")
> +        atexit.register(shutil.rmtree, self._tmpdir)
> +
> +        self._ssh_key_file = os.path.join(self._tmpdir, "id_rsa")
> +        open(self._ssh_key_file, "w").write(SSH_KEY)
> +        subprocess.check_call(["chmod", "600", self._ssh_key_file])
> +
> +        self._ssh_pub_key_file = os.path.join(self._tmpdir, "id_rsa.pub")
> +        open(self._ssh_pub_key_file, "w").write(SSH_PUB_KEY)

As above, I think it would be better just to keep copies of the keys in
the tests directory rather than in the python source.

> +
> +        self.debug = debug
> +        self._stderr = sys.stderr
> +        self._devnull = open("/dev/null", "w")

You can use os.devnull as a portable reference.

> +        if self.debug:
> +            self._stdout = sys.stdout
> +        else:
> +            self._stdout = self._devnull
> +        self._args = [ \
> +            "-nodefaults", "-m", "2G",
> +            "-cpu", "host",
> +            "-netdev", "user,id=vnet,hostfwd=:0.0.0.0:0-:22",

It doesn't help that howstfwd is poorly documented. Are we trying to map
an ephemeral port to the guests 22?

> +            "-device", "virtio-net-pci,netdev=vnet",
> +            "-vnc", ":0,to=20",

Do we need a GUI?

> +            "-serial", "file:%s" % os.path.join(self._tmpdir,
> "serial.out")]
> +        if vcpus:
> +            self._args += ["-smp", str(vcpus)]
> +        if os.access("/dev/kvm", os.R_OK | os.W_OK):
> +            self._args += ["-enable-kvm"]
> +        else:
> +            logging.info("KVM not available, not using -enable-kvm")
> +        self._data_args = []
> +
> +    def _download_with_cache(self, url, sha256sum=None):
> +        def check_sha256sum(fname):
> +            if not sha256sum:
> +                return True
> +            checksum = subprocess.check_output(["sha256sum", fname]).split()[0]
> +            return sha256sum == checksum
> +
> +        cache_dir = os.path.expanduser("~/.cache/qemu-vm/download")
> +        if not os.path.exists(cache_dir):
> +            os.makedirs(cache_dir)
> +        fname = os.path.join(cache_dir, hashlib.sha1(url).hexdigest())
> +        if os.path.exists(fname) and check_sha256sum(fname):
> +            return fname
> +        logging.debug("Downloading %s to %s...", url, fname)
> +        subprocess.check_call(["wget", "-c", url, "-O", fname + ".download"],
> +                              stdout=self._stdout,
> stderr=self._stderr)

Using wget rather than doing it internally adds a utility requirement.
Is doing a pure python urllib2 fetch too slow for this?

> +        os.rename(fname + ".download", fname)
> +        return fname
> +
> +    def _ssh_do(self, user, cmd, check, interactive=False):
> +        ssh_cmd = ["ssh", "-q",
> +                   "-o", "StrictHostKeyChecking=no",
> +                   "-o", "UserKnownHostsFile=/dev/null",
> +                   "-o", "ConnectTimeout=1",
> +                   "-p", self.ssh_port, "-i", self._ssh_key_file]
> +        if interactive:
> +            ssh_cmd += ['-t']
> +        assert not isinstance(cmd, str)
> +        ssh_cmd += ["%s@127.0.0.1" % user] + list(cmd)
> +        logging.debug("ssh_cmd: %s", " ".join(ssh_cmd))
> +        r = subprocess.call(ssh_cmd,
> +                            stdin=sys.stdin if interactive else self._devnull,
> +                            stdout=sys.stdout if interactive else self._stdout,
> +                            stderr=sys.stderr if interactive else self._stderr)
> +        if check and r != 0:
> +            raise Exception("SSH command failed: %s" % cmd)
> +        return r
> +
> +    def ssh(self, *cmd):
> +        return self._ssh_do(self.GUEST_USER, cmd, False)
> +
> +    def ssh_interactive(self, *cmd):
> +        return self._ssh_do(self.GUEST_USER, cmd, False, True)
> +
> +    def ssh_root(self, *cmd):
> +        return self._ssh_do("root", cmd, False)
> +
> +    def ssh_check(self, *cmd):
> +        self._ssh_do(self.GUEST_USER, cmd, True)
> +
> +    def ssh_root_check(self, *cmd):
> +        self._ssh_do("root", cmd, True)
> +
> +    def build_image(self, img):
> +        raise NotImplementedError
> +
> +    def add_source_dir(self, src_dir):
> +        name = "data-" + hashlib.sha1(src_dir).hexdigest()[:5]
> +        tarfile = os.path.join(self._tmpdir, name + ".tar")
> +        logging.debug("Creating archive %s for src_dir dir: %s", tarfile, src_dir)
> +        subprocess.check_call(["./scripts/archive-source.sh", tarfile],
> +                              cwd=src_dir, stdin=self._devnull,
> +                              stdout=self._stdout, stderr=self._stderr)
> +        self._data_args += ["-drive",
> +                            "file=%s,if=none,id=%s,cache=writeback,format=raw" % \
> +                                    (tarfile, name),
> +                            "-device",
> +                            "virtio-blk,drive=%s,serial=%s,bootindex=1" % (name, name)]
> +
> +    def boot(self, img, extra_args=[]):
> +        args = self._args + [
> +            "-device", "VGA",

Is specifying a display device at boot time really needed (say rather
than further up with the rest of the machine description). Do we even
want a display given use ssh/serial for everything?

> +            "-drive", "file=%s,if=none,id=drive0,cache=writeback" % img,
> +            "-device", "virtio-blk,drive=drive0,bootindex=0"]
> +        args += self._data_args + extra_args
> +        logging.debug("QEMU args: %s", " ".join(args))
> +        guest = QEMUMachine(binary=os.environ.get("QEMU", "qemu-system-x86_64"),
> +                            args=args)
> +        guest.launch()
> +        atexit.register(self.shutdown)
> +        self._guest = guest
> +        usernet_info = guest.qmp("human-monitor-command",
> +                                 command_line="info usernet")
> +        self.ssh_port = None
> +        for l in usernet_info["return"].splitlines():
> +            fields = l.split()
> +            if "TCP[HOST_FORWARD]" in fields and "22" in fields:
> +                self.ssh_port = l.split()[3]
> +        if not self.ssh_port:
> +            raise Exception("Cannot find ssh port from 'info usernet':\n%s" % \
> +                            usernet_info)
> +
> +    def wait_ssh(self, seconds=120):
> +        starttime = datetime.datetime.now()
> +        guest_up = False
> +        while (datetime.datetime.now() - starttime).total_seconds() < seconds:
> +            if self.ssh("exit 0") == 0:
> +                guest_up = True
> +                break
> +            time.sleep(1)
> +        if not guest_up:
> +            raise Exception("Timeout while waiting for guest ssh")
> +
> +    def shutdown(self):
> +        self._guest.shutdown()
> +
> +    def wait(self):
> +        self._guest.wait()
> +
> +    def qmp(self, *args, **kwargs):
> +        return self._guest.qmp(*args, **kwargs)
> +
> +def parse_args(vm_name):
> +    parser = optparse.OptionParser(description="""
> +    VM test utility.  Exit codes: 0 = success, 1 = command line error, 2 = environment initialization failed, 3 = test command failed""")
> +    parser.add_option("--debug", "-D", action="store_true",
> +                      help="enable debug output")
> +    parser.add_option("--image", "-i", default="%s.img" % vm_name,
> +                      help="image file name")
> +    parser.add_option("--force", "-f", action="store_true",
> +                      help="force build image even if image exists")
> +    parser.add_option("--jobs", type=int, default=multiprocessing.cpu_count() / 2,
> +                      help="number of virtual CPUs")
> +    parser.add_option("--build-image", "-b", action="store_true",
> +                      help="build image")
> +    parser.add_option("--build-qemu",
> +                      help="build QEMU from source in guest")
> +    parser.add_option("--interactive", "-I", action="store_true",
> +                      help="Interactively run command")
> +    parser.disable_interspersed_args()
> +    return parser.parse_args()
> +
> +def main(vmcls):
> +    try:
> +        args, argv = parse_args(vmcls.name)
> +        if not argv and not args.build_qemu and not args.build_image:
> +            print "Nothing to do?"
> +            return 1
> +        if args.debug:
> +            logging.getLogger().setLevel(logging.DEBUG)
> +        vm = vmcls(debug=args.debug, vcpus=args.jobs)
> +        if args.build_image:
> +            if os.path.exists(args.image) and not args.force:
> +                sys.stderr.writelines(["Image file exists: %s\n" % args.image,
> +                                      "Use --force option to overwrite\n"])
> +                return 1
> +            return vm.build_image(args.image)
> +        if args.build_qemu:
> +            vm.add_source_dir(args.build_qemu)
> +            cmd = [vm.BUILD_SCRIPT.format(
> +                   configure_opts = " ".join(argv),
> +                   jobs=args.jobs)]
> +        else:
> +            cmd = argv
> +        vm.boot(args.image + ",snapshot=on")

If this fails it's fairly cryptic:

/home/alex/lsrc/qemu/qemu.git/tests/vm/openbsd  --debug   --image "tests/vm/openbsd.img" --build-qemu /home/alex/lsrc/qemu/qemu.git
DEBUG:root:Creating archive ./vm-test-fxejnB.tmp/data-2de24.tar for src_dir dir: /home/alex/lsrc/qemu/qemu.git
DEBUG:root:QEMU args: -nodefaults -m 2G -cpu host -netdev user,id=vnet,hostfwd=:0.0.0.0:0-:22 -device virtio-net-pci,netdev=vnet -vnc :0,to=20 -serial file:./vm-test-fxejnB.tmp/serial.out -smp 4 -enable-kvm -device VGA -drive file=tests/vm/openbsd.img,snapshot=on,if=none,id=drive0,cache=writeback -device virtio-blk,drive=drive0,bootindex=0 -drive file=./vm-test-fxejnB.tmp/data-2de24.tar,if=none,id=data-2de24,cache=writeback,format=raw -device virtio-blk,drive=data-2de24,serial=data-2de24,bootindex=1
Failed to prepare guest environment
Traceback (most recent call last):
  File "/home/alex/lsrc/qemu/qemu.git/tests/vm/basevm.py", line 260, in main
    vm.boot(args.image + ",snapshot=on")
  File "/home/alex/lsrc/qemu/qemu.git/tests/vm/basevm.py", line 184, in boot
    guest.launch()
  File "/home/alex/lsrc/qemu/qemu.git/tests/vm/../../scripts/qemu.py", line 151, in launch
    self._post_launch()
  File "/home/alex/lsrc/qemu/qemu.git/tests/vm/../../scripts/qemu.py", line 135, in _post_launch
    self._qmp.accept()
  File "/home/alex/lsrc/qemu/qemu.git/tests/vm/../../scripts/qmp/qmp.py", line 147, in accept
    return self.__negotiate_capabilities()
  File "/home/alex/lsrc/qemu/qemu.git/tests/vm/../../scripts/qmp/qmp.py", line 60, in __negotiate_capabilities
    raise QMPConnectError
QMPConnectError

I assume QEMU failed to boot and might have given us a message that
would be useful.


> +        vm.wait_ssh()
> +    except Exception as e:
> +        if isinstance(e, SystemExit) and e.code == 0:
> +            return 0
> +        sys.stderr.write("Failed to prepare guest environment\n")
> +        traceback.print_exc()
> +        return 2
> +
> +    if args.interactive:
> +        if vm.ssh_interactive(*cmd) == 0:
> +            return 0
> +        vm.ssh_interactive()
> +        return 3
> +    else:
> +        if vm.ssh(*cmd) != 0:
> +            return 3


--
Alex Bennée