Minimize Docker image #467
Conversation
Shfmt v3.0.0 no longer has an external dependency on diff, so we can package the shfmt binary in the Docker image standalone, without busybox.
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We had briefly discussed this in #68; in particular, I laid out what I'd do in #68 (comment) a couple of weeks ago. This PR as-is is probably not a good idea, because plenty of users need a Docker image with shfmt as well as a shell installed. For example, that's a requirement for Gitlab CI. A bit silly, I know, but that's how the world works. If you want to have a try at the duplicate images (scratch and alpine), I'll be happy to review. If not, please open an issue, and I'll probably get to it sometime in January. |
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I see that you're currently using Docker Hub autobuilds. Unfortunately, they are not very configurable, e.g. AFAIK you can't specify a --target for the build, which would be the handy way to build two images from a single docker file. Are you open to switch the docker image build and publish to a different CI? E.g. Github Actions, which you are already using, should be able to handle that. |
Ah, that's a neat trick. I was imagining that maintaining two Dockerfiles was the only way. I assume we'd still have scratch be the default target, or is there no way to do that?
Yes, that's fine. Really, the only reason I did it via Docker Hub is because I liked how it shows you the Dockerfile directly, as well as how it built each of the images. Is there a way to show the Dockerfile from builds pushed from our CI here? If you are happy to do most of the work, I can do the bits I assume you won't be able to, like turning off docker hub auto-builds and adding the right secret to CI. |
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Do you want to focus on #468 and close this, since the changes here are included there? Or do you prefer keeping the changes as two commits? |
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Doing everything in #468 SGTM. |
This is a proposal related to #467. It builds two docker images, the busybox image as is currently built as well as a minimal image containing only the shfmt binary. In addition, the docker images are built as multi-architecture images which is a recent feature supported by docker's buildx extension. See how my test images report availability for multiple architectures. Each client pulling from Docker Hub automatically pulls only the appropriate architecture version for itself, so there is no additional overhead for the client. Clients don't need experimental features enabled for this (only the builder need them). The docker build and deployment is hooked into the existing Github Actions CI/CD pipeline, conditioned on all other builds and tests passing.
This is a proposal for a minimized Docker image that only contains the shfmt binary. It reduces the size a little by not packaging up busybox. Up to you if you want that.
Also added more usage instructions to the README.