'docker context ls' or 'docker context inspect' slow responses with remote servers

[aduzsardi]

• [x] This is a bug report
• [x] This is a feature request
• [x] I searched existing issues before opening this one

Expected behavior

Return current used docker context faster

Actual behavior

while using a remote docker host context through a VPN or over the internet, the listing and inspecting of the contexts is very slow

$ time docker context ls
NAME                DESCRIPTION                               DOCKER ENDPOINT                 KUBERNETES ENDPOINT   ORCHESTRATOR
bb-dev *            BB Dev Environment                        ssh://deploy@192.168.213.214                         swarm
default             Current DOCKER_HOST based configuration   unix:///var/run/docker.sock                           swarm

real    0m2.547s
user    0m0.020s
sys 0m0.015s

If using the default (local) docker context , everything seems to be ok

$ docker context use default
Current context is now "default"
$ time docker context ls
NAME                DESCRIPTION                               DOCKER ENDPOINT                 KUBERNETES ENDPOINT   ORCHESTRATOR
bb-dev              BB Dev Environment                        ssh://deploy@192.168.213.214                         swarm
default *           Current DOCKER_HOST based configuration   unix:///var/run/docker.sock                           swarm

real    0m0.026s
user    0m0.024s
sys 0m0.010s

Steps to reproduce the behavior

Output of docker version:

lient: Docker Engine - Community
 Version:           19.03.11
 API version:       1.40
 Go version:        go1.13.10
 Git commit:        42e35e61f3
 Built:             Mon Jun  1 09:12:34 2020
 OS/Arch:           linux/amd64
 Experimental:      false

Server: Docker Engine - Community
 Engine:
  Version:          19.03.11
  API version:      1.40 (minimum version 1.12)
  Go version:       go1.13.10
  Git commit:       42e35e61f3
  Built:            Mon Jun  1 09:11:07 2020
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          1.2.13
  GitCommit:        7ad184331fa3e55e52b890ea95e65ba581ae3429
 runc:
  Version:          1.0.0-rc10
  GitCommit:        dc9208a3303feef5b3839f4323d9beb36df0a9dd
 docker-init:
  Version:          0.18.0
  GitCommit:        fec3683

Output of docker info:

Client:
 Debug Mode: false

Server:
 Containers: 1
  Running: 0
  Paused: 0
  Stopped: 1
 Images: 37
 Server Version: 19.03.11
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Native Overlay Diff: true
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 7ad184331fa3e55e52b890ea95e65ba581ae3429
 runc version: dc9208a3303feef5b3839f4323d9beb36df0a9dd
 init version: fec3683
 Security Options:
  apparmor
  seccomp
   Profile: default
 Kernel Version: 5.4.0-37-generic
 Operating System: Ubuntu 20.04 LTS
 OSType: linux
 Architecture: x86_64
 CPUs: 12
 Total Memory: 15.56GiB
 Name: aduzsardi-nix
 ID: V6CN:HNWD:PENV:MYG3:2ORG:SYRC:P6LD:HJNM:P3GS:OZ3K:7VTR:6QWV
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Registry: https://index.docker.io/v1/
 Labels:
 Experimental: false
 Insecure Registries:
  gitlab.bigbrother.lokaal:5005
  127.0.0.0/8
 Live Restore Enabled: false

WARNING: No swap limit support

Additional environment details (AWS, VirtualBox, physical, etc.)

I'm connecting to remote docker or docker swarm hosts trough VPNs from home to office network

I want to set my bash prompt to show the docker context currently in use so i know where i am at all times , but the time it takes to return my prompt every time i press the return key on the keyboard takes about ~3s of so it's not usable

The script i was using

$ cat /etc/profile.d/docker_prompt.sh

#!/bin/bash

_get_docker_ctx()
{
    # Get current context
    if type docker &>/dev/null; then
        CONTEXT=$(docker context ls | grep -F '*' | awk '{ print $1}')
    fi
}

__docker_ps1()
{
    _get_docker_ctx
    if [ -n "$CONTEXT" ]; then
        echo "[dctx: ${CONTEXT}] - "
    fi
}

__colored_docker_ps1()
{
    _get_docker_ctx
    if [ -n "$CONTEXT" ]; then
        echo -e "\e[1m\e[37m[\e[92mdctx: \e[36m${CONTEXT}\e[37m] - \e[0m"
    fi

}

And PS1 prompt

export PS1='$(__colored_docker_ps1)\[\e]0;\u@\h: \w\a\]${debian_chroot:+($debian_chroot)}\u@\h:\w\$'

Proposal

It would be nice if we could read the currently used context from a file or config , so every time you run docker context use ... the config would be updated with the "current-context: something" like kubectl does

[thaJeztah]

This use-case will be addressed by https://github.com/docker/cli/pull/2500 (which will be in the upcoming 20.x release of docker)

that said; performance of docker context ls is on our radar (given that it's a local action, it shouldn't have to depend on the connection-speed with the currently selected context).

[thaJeztah]

Let me move this ticket to the docker/cli issue tracker for visibility.

[aduzsardi]

Currently if you select a context and the connection with the docker host is down , the commands just hang , will this also be addressed ? Thank you

[thaJeztah]

Currently if you select a context and the connection with the docker host is down , the commands just hang , will this also be addressed ?

@aduzsardi docker 19.03.12 was released with some improvements (from https://github.com/docker/cli/pull/2424 and https://github.com/docker/cli/pull/2515). Not sure from the top of my head if those resolve the full issue, but you could give 19.03.12 a spin to see if it performs better

[aduzsardi]

thank you for the notice , updated docker on my system but i don't see any changes for my use cases

aduzsardi@aduzsardi-nix: ~
└─$ ▶ time __docker_ps1
[dctx: bb-dev]

real    0m3.928s
user    0m0.024s
sys 0m0.015s

keeping in mind that i go through a few routers and a VPN from one country to another to reach my remote docker host also if i disconnect the VPN and trying to switch back the docker context to the default , it hangs forever until finally changes it back to default

[brynmathias]

I am seeing similar on mac os x.

~ via 🐍 3.8.0 took 14s
➜ time docker context ls
NAME                TYPE                DESCRIPTION                               DOCKER ENDPOINT               KUBERNETES ENDPOINT                ORCHESTRATOR
default *           moby                Current DOCKER_HOST based configuration   unix:///var/run/docker.sock   https://localhost:6443 (default)   swarm
docker context ls  0.10s user 0.03s system 2% cpu 5.073 total

~ via 🐍 3.8.0 took 5s
➜ time docker context ls
NAME                TYPE                DESCRIPTION                               DOCKER ENDPOINT               KUBERNETES ENDPOINT                ORCHESTRATOR
default *           moby                Current DOCKER_HOST based configuration   unix:///var/run/docker.sock   https://localhost:6443 (default)   swarm
docker context ls  0.09s user 0.04s system 2% cpu 4.616 total

I only have the context that was setup by installing docker desktop However I noticed the performance degradation when setting up a windows docker context in virtual box

[smhc]

Looks related to both https://github.com/docker/cli/issues/1955 and https://github.com/docker/cli/issues/3096 Both of which report the inability to run local commands when using a context that is either invalid or slow performing.

[guillenotfound]

Any updates on this?

[aduzsardi]

i don't see much activity on fixing issues on docker repositories, so probably nothing new about this one either you are better of not using docker contexts

[tbenthompson]

This is still a problem. It'd be nice to include the docker context in my prompt like spaceship does by default but it makes my zsh prompt super slow so I have to turn it off.

[a-abella]

@tbenthompson If you're still looking, the current non-default context is listed in ~/.docker/config.json under .currentContext. I added current context to my PS1 prompt by sourcing it from this file.

$ time jq -r .currentContext ~/.docker/config.json
swarm-qa

real    0m0.003s
user    0m0.003s
sys     0m0.000s

When the currentContext = default, this item is absent from config.json

I suppose there's no guarantees that this is a stable way to get this information, but it will have to do.

[thaJeztah]

If you have the docker 23.0 CLI installed you should now also be able to use docker context show to get the currently configured context. That command only shows the name of the configured context, but (intentionally) won't validate if the context's metadata is valid and/or if it's able to connect using the context;

docker context show
default

DOCKER_CONTEXT=nosuchcontext docker context show
nosuchcontext

It follows the same logic as is used to resolve the context to use when running commands, for example, setting a DOCKER_HOST will disable using the context, and switch back to "default" (with the host configured through DOCKER_HOST);

DOCKER_CONTEXT=nosuchcontxt DOCKER_HOST=unix://var/run/docker.sock docker context show
default