Support for Docker contexts, or a Docker socket in an alternative location

[breun]

Description

I'm using Colima to run Docker containers on macOS and pulling and running images via the docker CLI tool works just fine. Colima created and activated a Docker context with a socket in $HOME/.colima/default/docker.sock:

❯ docker context ls
NAME              DESCRIPTION                               DOCKER ENDPOINT                                       KUBERNETES ENDPOINT                ORCHESTRATOR
colima *          colima                                    unix:///Users/nbreunese/.colima/default/docker.sock                                      
default           Current DOCKER_HOST based configuration   unix:///var/run/docker.sock                           https://35.204.107.135 (default)   swarm
rancher-desktop   Rancher Desktop moby context              unix:///Users/nbreunese/.rd/docker.sock

It seems that docker-maven-plugin does not find or use this Docker context, because when I run a Maven project which uses docker-maven-plugin I get the following error:

No <dockerHost> given, no DOCKER_HOST environment variable, no read/writable '/var/run/docker.sock' or '//./pipe/docker_engine' and no external provider like Docker machine configured

According to the Global Configuration section in the documentation, docker-maven-plugin checks /var/run/docker.sock on macOS, but I don't see mention of support for Docker contexts. Does docker-maven-plugin support Docker contexts? If not, could this be added? If it does, it does not seem to work for me. In that case, is there a way to specify a local Docker socket via the DOCKER_HOST environment variable?

Info

• docker-maven-plugin version : 0.40.1
• Maven version (mvn -v) : 3.8.6

* Docker version : 

❯ docker version Client: Version: 20.10.14 API version: 1.41 Go version: go1.18.1 Git commit: 0a7772e Built: Tue May 03 01:09:34 2022 OS/Arch: darwin/amd64 Context: colima Experimental: true

Server: Engine: Version: 20.10.11 API version: 1.41 (minimum version 1.12) Go version: go1.16.15 Git commit: 847da184ad5048b27f5bdf9d53d070f731b43180 Built: Wed Apr 13 23:41:08 2022 OS/Arch: linux/amd64 Experimental: false containerd: Version: v1.5.8 GitCommit: 1e5ef943eb76627a6d3b6de8cd1ef6537f393a71 runc: Version: 1.0.0-rc95 GitCommit: b9ee9c6314599f1b4a7f497e1f1f856fe433d3b7 docker-init: Version: 0.19.0 GitCommit:

* If it's a bug, how to reproduce : Run Colima and then a Maven build with `docker-maven-plugin`
* If it's a feature request, what is your use case : Using `docker-maven-plugin` that works with Colima (and other tools that don't put the Docker socket at `/var/run/docker.sock`.
* Sample project : Any project that uses `docker-maven-plugin`

[rhuss]

You are correct, dmp doesn't support Docker contexts, but does it work if you set the environment variable DOCKER_HOST to "unix:///Users/nbreunese/.colima/default/docker.sock" (or alternatively the <dockerHost> plugin configuration variable) ?

[breun]

Setting DOCKER_HOST like that indeed works, thanks! It would still be nice if docker-maven-plugin would add support for Docker contexts, but I can use this as a workaround for now.