[FEATURE]: Control path of docker config for `publish`

[salotz]

Feature Request

Background / Motivation

I am trying to run garden publish in a CI pipeline where it would be very convenient to pass the path to the docker config folder as an environment variable. In my CI system I use previous step to create the docker config.json and pass it to the garden publish task, so I have to use shell scripting to copy it to ~/.docker/config.json.

What should the user be able to do?

DOCKER_CONFIG=path/to/my/docker garden publish my-build --tag latest

Why do they want to do this? What problem does it solve?

Adds more flexibility and options to how we can configure this job. Depending on the context system some methods are easier than others. Using environment variables is usually the most easily supported.

Suggested Implementation(s)

I first tried using DOCKER_CONFIG as the documentation indicates that this is how it works.

I then understood from the logs that you are using regctl for the publish command (despite using skopeo for other tasks). So I looked in their docs to see if it was controllable by an environment variable, which it wasn't.

So either you can use a tool that supports an environment variable or create your own and map that to however that wrapped tool uses it.

How important is this feature for you/your team?

🌵 Not having this feature makes using Garden painful

[stefreak]

@salotz I just checked the docs and code of regctl, and it should respect the DOCKER_CONFIG environment variable. Would it be possible for you to share an error message with us here, and/or what happens when running https://github.com/regclient/regclient directly with your config?

Thank you 👍

[salotz]

@stefreak Where was that in the documentation?

I don't have logs, but even then there wouldn't be anything to show this. You just get an error that you are not authorized by the registry.

I think that if you have docker also installed regctl will use that to configure its own credentials. In which case docker of course will respect that and then the process will succeed. However, in this case there is no docker for regctl to use.

Sorry for not being able to show proof, but it should be straightforward to check in a container.

[stefreak]

@salotz looking at the source code of regctl, it seems to only respect the contents of the DOCKER_CONFIG env variable if the ~/.docker/config.json doesn't exist.
Is it possible that the ~/.docker/config.json exists as well in your case? In that case, we should open an issue with regctl and/or propose a PR to change the order of checking for config file existence.

[salotz]

@stefreak It likely was there yes. I don't have this environment to confirm anymore. (I was running Garden in Concourse CI but it was way too buggy.)