Re: [Qemu-devel] [PULL 2/6] docker.py: add podman support

[Philippe Mathieu-Daudé]

On 8/22/19 3:47 PM, Marc-André Lureau wrote:
> Add a --engine option to select either docker, podman or auto.
> 
> Among other advantages, podman allows to run rootless & daemonless
> containers, fortunately sharing compatible CLI with docker.
> 
> With current podman, we have to use a uidmap trick in order to be able
> to rw-share the ccache directory with the container user.
> 
> With a user 1000, the default mapping is:                                     
>                                                                               
>                                                       1000 (host) -> 0 
> (container).
> So write access to /var/tmp/ccache ends will end with permission
> denied error.
> 
> With "--uidmap 1000:0:1 --uidmap 0:1:1000", the mapping is:
> 1000 (host) -> 0 (container, 1st namespace) -> 1000 (container, 2nd 
> namespace).
> (the rest is mumbo jumbo to avoid holes in the range of UIDs)
> 
> A future podman version may have an option such as --userns-keep-uid.
> Thanks to Debarshi Ray <address@hidden> for the help!
> 
> Signed-off-by: Marc-André Lureau <address@hidden>
> Acked-by: Alex Bennée <address@hidden>
> Reviewed-by: Daniel P. Berrangé <address@hidden>
> ---
>  tests/docker/docker.py | 48 +++++++++++++++++++++++++++++++++++++-----
>  1 file changed, 43 insertions(+), 5 deletions(-)
> 
> diff --git a/tests/docker/docker.py b/tests/docker/docker.py
> index f15545aeea..ac5baab4ca 100755
> --- a/tests/docker/docker.py
> +++ b/tests/docker/docker.py
> @@ -20,6 +20,7 @@ import hashlib
>  import atexit
>  import uuid
>  import argparse
> +import enum

This broke Shippable:
https://app.shippable.com/github/qemu/qemu/runs/1897/summary/console

  Traceback (most recent call last):
    File "./tests/docker/docker.py", line 23, in <module>
      import enum
  ImportError: No module named enum

>  import tempfile
>  import re
>  import signal
> @@ -38,6 +39,26 @@ FILTERED_ENV_NAMES = ['ftp_proxy', 'http_proxy', 
> 'https_proxy']
>  
>  DEVNULL = open(os.devnull, 'wb')
>  
> +class EngineEnum(enum.IntEnum):
> +    AUTO = 1
> +    DOCKER = 2
> +    PODMAN = 3
> +
> +    def __str__(self):
> +        return self.name.lower()
> +
> +    def __repr__(self):
> +        return str(self)
> +
> +    @staticmethod
> +    def argparse(s):
> +        try:
> +            return EngineEnum[s.upper()]
> +        except KeyError:
> +            return s
> +
> +
> +USE_ENGINE = EngineEnum.AUTO
>  
>  def _text_checksum(text):
>      """Calculate a digest string unique to the text content"""
> @@ -48,9 +69,14 @@ def _file_checksum(filename):
>      return _text_checksum(open(filename, 'rb').read())
>  
>  
> -def _guess_docker_command():
> -    """ Guess a working docker command or raise exception if not found"""
> -    commands = [["docker"], ["sudo", "-n", "docker"]]
> +def _guess_engine_command():
> +    """ Guess a working engine command or raise exception if not found"""
> +    commands = []
> +
> +    if USE_ENGINE in [EngineEnum.AUTO, EngineEnum.PODMAN]:
> +        commands += [["podman"]]
> +    if USE_ENGINE in [EngineEnum.AUTO, EngineEnum.DOCKER]:
> +        commands += [["docker"], ["sudo", "-n", "docker"]]
>      for cmd in commands:
>          try:
>              # docker version will return the client details in stdout
> @@ -61,7 +87,7 @@ def _guess_docker_command():
>          except OSError:
>              pass
>      commands_txt = "\n".join(["  " + " ".join(x) for x in commands])
> -    raise Exception("Cannot find working docker command. Tried:\n%s" %
> +    raise Exception("Cannot find working engine command. Tried:\n%s" %
>                      commands_txt)
>  
>  
> @@ -190,7 +216,7 @@ def _dockerfile_preprocess(df):
>  class Docker(object):
>      """ Running Docker commands """
>      def __init__(self):
> -        self._command = _guess_docker_command()
> +        self._command = _guess_engine_command()
>          self._instances = []
>          atexit.register(self._kill_instances)
>          signal.signal(signal.SIGTERM, self._kill_instances)
> @@ -340,6 +366,11 @@ class RunCommand(SubCommand):
>          if args.run_as_current_user:
>              uid = os.getuid()
>              argv = [ "-u", str(uid) ] + argv
> +            docker = Docker()
> +            if docker._command[0] == "podman":
> +                argv = [ "--uidmap", "%d:0:1" % uid,
> +                         "--uidmap", "0:1:%d" % uid,
> +                         "--uidmap", "%d:%d:64536" % (uid + 1, uid + 1)] + 
> argv
>          return Docker().run(argv, args.keep, quiet=args.quiet)
>  
>  
> @@ -507,6 +538,8 @@ class ProbeCommand(SubCommand):
>                  print("yes")
>              elif docker._command[0] == "sudo":
>                  print("sudo")
> +            elif docker._command[0] == "podman":
> +                print("podman")
>          except Exception:
>              print("no")
>  
> @@ -602,9 +635,13 @@ class CheckCommand(SubCommand):
>  
>  
>  def main():
> +    global USE_ENGINE
> +
>      parser = argparse.ArgumentParser(description="A Docker helper",
>                                       usage="%s <subcommand> ..." %
>                                       os.path.basename(sys.argv[0]))
> +    parser.add_argument("--engine", type=EngineEnum.argparse, 
> choices=list(EngineEnum),
> +                        help="specify which container engine to use")
>      subparsers = parser.add_subparsers(title="subcommands", help=None)
>      for cls in SubCommand.__subclasses__():
>          cmd = cls()
> @@ -613,6 +650,7 @@ def main():
>          cmd.args(subp)
>          subp.set_defaults(cmdobj=cmd)
>      args, argv = parser.parse_known_args()
> +    USE_ENGINE = args.engine
>      return args.cmdobj.run(args, argv)
>  
>  
>