Add Docker image for pre-commit

[rally-carlos]

Is making actionlint available as a Docker image a possibility?

This PR illustrates what the implementation could look like. An account on a Docker image repository is required.

[rhysd]

I think using single binary would be better than using Docker for the following reasons:

• Overhead is larger. Running container costs more than running a single executable. The Docker image includes entire Go toolchain so it would also require much storage sorry this is not true thanks to Docker's multi-stage builds
• shellcheck and pyflakes integrations are not available. To enable them, we also need to install them in the image. So maintaining the image is a bit harder

I think, it is easiest way for tools to download executable by using the donwload script and execute the downloaded binary directly.

[rhysd]

OK, I changed my mind. I'll consider to prepare some Docker image for actionlint. I think it is useful for those who don't want to install dependencies like shellcheck or pyflake locally. I can't merge this branch strait forward since I need to investigate how to make a smaller image and add tests for the image.

After the image is prepared, would you rebase this branch onto the latest and add the pre-commit configuration?

[drts01]

I have pushed a Dockerfile to include the dependencies with Alpine Linux as the base image. To make the image smaller, may not be worth the ROI, IMO.

I have also included a test to verify the container can build and run. Does this cover what you are looking for?

P.S. FWIW, I got the Docker idea from hadolint pre-commit implementation. 😄

[rhysd]

Thank you for the update. Looks good. Would you wait for a few days? I'm now improving type checking in other branch. After finishing the task, let me try this branch.

[rhysd]

I confirmed it worked. I released the first version manually: https://hub.docker.com/repository/docker/rhysd/actionlint

I'll add some commits for follow up.

[rhysd]

Merged 👍 Thank you for the additions.