docker.py: add podman support

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 <rishi@redhat.com> for the help!

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
This commit is contained in:
Marc-André Lureau 2019-07-12 16:46:13 +04:00
parent 2461d80e6c
commit 9459f75413

View File

@ -20,6 +20,7 @@ import hashlib
import atexit
import uuid
import argparse
import 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)