Re: [Qemu-devel] [PATCH v3 01/13] tests: Add utilities for docker testing

From: "Alex Bennée" <alex.bennee@linaro.org>
To: Fam Zheng <famz@redhat.com>
Cc: kwolf@redhat.com, peter.maydell@linaro.org, sw@weilnetz.de,
	qemu-devel@nongnu.org, stefanha@redhat.com,
	Paolo Bonzini <pbonzini@redhat.com>,
	jsnow@redhat.com, david@gibson.dropbear.id.au
Subject: Re: [Qemu-devel] [PATCH v3 01/13] tests: Add utilities for docker testing
Date: Fri, 11 Mar 2016 15:04:48 +0000	[thread overview]
Message-ID: <87wpp9t5rj.fsf@linaro.org> (raw)
In-Reply-To: <1457086720-30391-2-git-send-email-famz@redhat.com>

Fam Zheng <famz@redhat.com> writes:

> docker_run: A wrapper for "docker run" (or "sudo -n docker run" if
> necessary), which takes care of killing and removing the running
> container at SIGINT.
>
> docker_clean: A tool to tear down all the containers including inactive
> ones that are started by docker_run.
>
> docker_build: A tool to compare an image from given dockerfile and
> rebuild it if they're different.

This commit text needs updating with the actual calling conventions.

>
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  tests/docker/docker.py | 180 +++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 180 insertions(+)
>  create mode 100755 tests/docker/docker.py
>
> diff --git a/tests/docker/docker.py b/tests/docker/docker.py
> new file mode 100755
> index 0000000..22f537c
> --- /dev/null
> +++ b/tests/docker/docker.py
> @@ -0,0 +1,180 @@
> +#!/usr/bin/env python2
> +#
> +# Docker controlling module
> +#
> +# Copyright (c) 2016 Red Hat Inc.
> +#
> +# Authors:
> +#  Fam Zheng <famz@redhat.com>
> +#
> +# This work is licensed under the terms of the GNU GPL, version 2
> +# or (at your option) any later version. See the COPYING file in
> +# the top-level directory.

It's worth running pylint over this file. There are a number of
missing newlines/spaces/long lines that aren't PEP friendly.

> +
> +import os
> +import sys
> +import subprocess
> +import json
> +import hashlib
> +import atexit
> +import uuid
> +import argparse
> +
> +class Docker(object):
> +    """ Running Docker commands """
> +    def __init__(self):
> +        self._command = self._guess_command()
> +        self._instances = []
> +        atexit.register(self._kill_instances)
> +
> +    def _do(self, cmd, quiet=True, **kwargs):
> +        if quiet:
> +            kwargs["stdout"] = subprocess.PIPE
> +        return subprocess.call(self._command + cmd, **kwargs)
> +
> +    def _do_kill_instances(self, only_known, only_active=True):
> +        cmd = ["ps", "-q"]
> +        if not only_active:
> +            cmd.append("-a")
> +        for i in self._output(cmd).split():
> +            resp = self._output(["inspect", i])
> +            labels = json.loads(resp)[0]["Config"]["Labels"]
> +            active = json.loads(resp)[0]["State"]["Running"]
> +            if not labels:
> +                continue
> +            instance_uuid = labels.get("com.qemu.instance.uuid", None)
> +            if not instance_uuid:
> +                continue
> +            if only_known and instance_uuid not in self._instances:
> +                continue
> +            print "Terminating", i
> +            if active:
> +                self._do(["kill", i])
> +            self._do(["rm", i])
> +
> +    def clean(self):
> +        self._do_kill_instances(False, False)
> +        return 0
> +
> +    def _kill_instances(self):
> +        return self._do_kill_instances(True)
> +
> +    def _output(self, cmd, **kwargs):
> +        return subprocess.check_output(self._command + cmd,
> +                                       stderr=subprocess.STDOUT,
> +                                       **kwargs)
> +
> +    def _guess_command(self):
> +        commands = [["docker"], ["sudo", "-n", "docker"]]
> +        for cmd in commands:
> +            if subprocess.call(cmd + ["images"],
> +                               stdout=subprocess.PIPE,
> +                               stderr=subprocess.PIPE) == 0:
> +                return cmd
> +        commands_txt = "\n".join(["  " + " ".join(x) for x in commands])
> +        raise Exception("Cannot find working docker command. Tried:\n%s" % commands_txt)
> +
> +    def get_image_dockerfile_checksum(self, tag):
> +        resp = self._output(["inspect", tag])
> +        labels = json.loads(resp)[0]["Config"].get("Labels", {})
> +        return labels.get("com.qemu.dockerfile-checksum", "")
> +
> +    def checksum(self, text):
> +        return hashlib.sha1(text).hexdigest()
> +
> +    def build_image(self, tag, dockerfile, df, quiet=True, argv=[]):
> +        tmp = dockerfile + "\n" + \
> +              "LABEL com.qemu.dockerfile-checksum=%s" % self.checksum(dockerfile)
> +        tmp_df = df + ".tmp"
> +        tmp_file = open(tmp_df, "wb")
> +        tmp_file.write(tmp)
> +        tmp_file.close()
> +        self._do(["build", "-t", tag, "-f", tmp_df] + argv + [os.path.dirname(df)],
> +                 quiet=quiet)
> +        os.unlink(tmp_df)

Use python's tempfile to do this. It handles all the lifetime issues for
you automatically - the file gets removed when the object goes out of scope.

> +
> +    def image_matches_dockerfile(self, tag, dockerfile):
> +        try:
> +            checksum = self.get_image_dockerfile_checksum(tag)
> +        except:
> +            return False
> +        return checksum == self.checksum(dockerfile)
> +
> +    def run(self, cmd, keep, quiet):
> +        label = uuid.uuid1().hex
> +        if not keep:
> +            self._instances.append(label)
> +        ret = self._do(["run", "--label", "com.qemu.instance.uuid=" + label] + cmd, quiet=quiet)
> +        if not keep:
> +            self._instances.remove(label)
> +        return ret
> +
> +class SubCommand(object):
> +    """A SubCommand template base class"""
> +    name = None # Subcommand name
> +    def args(self, parser):
> +        """Setup argument parser"""
> +        pass
> +    def run(self, args, argv):
> +        """Run command.
> +        args: parsed argument by argument parser.
> +        argv: remaining arguments from sys.argv.
> +        """
> +        pass
> +
> +class RunCommand(SubCommand):
> +    """Invoke docker run and take care of cleaning up"""
> +    name = "run"
> +    def args(self, parser):
> +        parser.add_argument("--keep", action="store_true",
> +                            help="Don't remove image when the command completes")
> +        parser.add_argument("--quiet", action="store_true",
> +                            help="Run quietly unless an error
> occured")

I suspect --quiet should be a shared global flag.

Also it would be worth adding help text to show the remaining args are
passed "as is" to the docker command line.

> +    def run(self, args, argv):
> +        return Docker().run(argv, args.keep, quiet=args.quiet)
> +
> +class BuildCommand(SubCommand):
> +    """ Build docker image out of a dockerfile"""
> +    name = "build"
> +    def args(self, parser):
> +        parser.add_argument("tag",
> +                            help="Image Tag")
> +        parser.add_argument("dockerfile",
> +                            help="Dockerfile name")
> +        parser.add_argument("--verbose", "-v", action="store_true",
> +                            help="Print verbose information")

I suspect --verbose should be a shared global flag.

> +
> +    def run(self, args, argv):
> +        dockerfile = open(args.dockerfile, "rb").read()
> +        tag = args.tag
> +
> +        dkr = Docker()
> +        if dkr.image_matches_dockerfile(tag, dockerfile):
> +            if args.verbose:
> +                print "Image is up to date."
> +            return 0
> +
> +        quiet = not args.verbose
> +        dkr.build_image(tag, dockerfile, args.dockerfile, quiet=quiet, argv=argv)
> +        return 0

I've seen this hang. Do builds always succeed?

> +
> +class CleanCommand(SubCommand):
> +    """Clean up docker instances"""
> +    name = "clean"
> +    def run(self, args, argv):
> +        Docker().clean()
> +        return 0
> +
> +def main():
> +    parser = argparse.ArgumentParser()
> +    subparsers = parser.add_subparsers()
> +    for cls in SubCommand.__subclasses__():
> +        cmd = cls()
> +        subp = subparsers.add_parser(cmd.name, help=cmd.__doc__)
> +        cmd.args(subp)
> +        subp.set_defaults(cmdobj=cmd)
> +    args, argv = parser.parse_known_args()
> +    return args.cmdobj.run(args, argv)

There are some niggles with help:

14:40 alex@zen/x86_64  [qemu.git/review/docker-v3]>./tests/docker/docker.py --help
usage: docker.py [-h] {run,build,clean} ...

positional arguments:
  {run,build,clean}

Positional? Really. You can only have one command at a time.

      run              Invoke docker run and take care of cleaning up
      build            Build docker image out of a dockerfile
      clean            Clean up docker instances

optional arguments:
  -h, --help         show this help message and exit

OK that's useful, but do we have args for build?

14:43 alex@zen/x86_64  [qemu.git/review/docker-v3]>./tests/docker/docker.py --help build
  usage: docker.py [-h] {run,build,clean} ...

positional arguments:
  {run,build,clean}
      run              Invoke docker run and take care of cleaning up
      build            Build docker image out of a dockerfile
      clean            Clean up docker instances

optional arguments:
  -h, --help         show this help message and exit

Hmm same result. We have to call like this:

14:43 alex@zen/x86_64  [qemu.git/review/docker-v3]  >./tests/docker/docker.py build --help
  usage: docker.py build [-h] [--verbose] tag dockerfile

positional arguments:
  tag            Image Tag
  dockerfile     Dockerfile name

optional arguments:
  -h, --help     show this help message and exit
  --verbose, -v  Print verbose information

Maybe there is someway to make this clearer.

> +
> +if __name__ == "__main__":
> +    sys.exit(main())

--
Alex Bennée