DockerCLI/cmd/docker
Sebastiaan van Stijn cf663b526a
cli: perform feature detection lazily
- Perform feature detection when actually needed, instead of during
  initializing
- Version negotiation is performed either when making an API request,
  or when (e.g.) running `docker help` (to hide unsupported features)
- Use a 2 second timeout when 'pinging' the daemon; this should be
  sufficient for most cases, and when feature detection failed, the
  daemon will still perform validation (and produce an error if needed)
- context.WithTimeout doesn't currently work with ssh connections (connhelper),
  so we're only applying this timeout for tcp:// connections, otherwise
  keep the old behavior.

Before this change:

    time sh -c 'DOCKER_HOST=tcp://42.42.42.41:4242 docker help &> /dev/null'
    real   0m32.919s
    user   0m0.370s
    sys    0m0.227s

    time sh -c 'DOCKER_HOST=tcp://42.42.42.41:4242 docker context ls &> /dev/null'
    real   0m32.072s
    user   0m0.029s
    sys    0m0.023s

After this change:

    time sh -c 'DOCKER_HOST=tcp://42.42.42.41:4242 docker help &> /dev/null'
    real   0m 2.28s
    user   0m 0.03s
    sys    0m 0.03s

    time sh -c 'DOCKER_HOST=tcp://42.42.42.41:4242 docker context ls &> /dev/null'
    real   0m 0.13s
    user   0m 0.02s
    sys    0m 0.02s

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit b39739123b)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2020-04-29 17:12:23 +02:00
..
docker.go cli: perform feature detection lazily 2020-04-29 17:12:23 +02:00
docker_test.go bump gotest.tools v3.0.1 for compatibility with Go 1.14 2020-04-21 16:43:18 +02:00
docker_windows.go Add windows resources to binary. 2017-05-15 18:03:03 -04:00