CI: cache syntest docker image
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Because it takes 3-5 minutes to build. I cobbled this config together from several incomplete sources: https://stackoverflow.com/questions/71348621/docker-re-use-container-image-by-caching https://github.com/docker/build-push-action/blob/master/docs/advanced/cache.md#github-cache https://github.com/docker/buildx/blob/master/docs/guides/cache/gha.md https://github.com/moby/buildkit#github-actions-cache-experimental https://docs.github.com/en/rest/actions/cache https://docs.github.com/en/actions/using-workflows/caching-dependencies-to-speed-up-workflows#restrictions-for-accessing-a-cache Also, the GitHub Actions cache exporter is experimental...
Just troubleshooting, don't mind me. Buildkit is disabled in Docker, by default. You have to enable it with that env. Because the cache is associated to buildkit, of course it should be enabled in the docker build of syntest.
Try with this install parameter to setup-buildx, that should achieve the same as DOCKER_BUILDKIT=1 and is referenced in the documentation for that action: https://github.com/docker/setup-buildx-action/blob/master/docs/advanced/install-default.md Also comments the scope param to build-push-action because the runner was complaining about it.
So syntax.py has an escape hatch to not build the image if it already exists. (Which is probably bad because it won't be rebuilt on syntect version changes but whatever.) By tagging the image with the name syntax.py expects, we can probably avoid the rebuild?
By setting an explicit image tag, with version (latest) and all, on both the python script and build-push-action.
After reviewing [^1]. Because it seems that only buildctl can import the cache, so let's use that command. [^1] https://github.com/moby/buildkit/tree/master#github-actions-cache-experimental
Instead of performing acrobatics / architecture astronautics to have the original script (syntax.py) fit both use cases (feedback loop in the dev's local + automated tests in CI). It's probably the right way to use build-push-action. Build, then run, instead of re-building again in a later step. I tried placing `syntax_ci.sh` in `.github/workflows/` but then it's not visible to the Github Actions runtime.
buildkit seems to be built for versatility, agnostic of the underlying engine / runtime / client / whatever Docker is supposed to be. So you need to explicitly tell it where you want the output of the build to be saved. load = true "is a shorthand for --output=type=docker"
The previous commit worked! The syntest image is properly generated and registered with `docker images`! But the job still fails because we need the part of syntax.py where it downloads the man syntax. Some syntax tests depend on that syntax being available in syntaxes/. Now, as the syntest image is already built when we hit syntax.py, it skips rebuilding the image. Which is par for the course: caching, based on docker/build-push-action. ETA: indeed, this version passes 🎉 🚀🚀
Remove failed/unneeded experiments from all the troubleshooting. The `with: install: true` in docker/setup-buildx-action is not needed because it aliases `docker build` to `docker buildx` which we don't use (not explicitly).
So the Github Actions cache prevents sharing a cache across branches, with some exceptions: Only the cache for the current branch, the base branch and the default branch is accessible by a workflow. I believe that by setting the cache scope to "main", all workflows, including those that run on main (default & usually base branch) will use the same scope. And such a scope should be accessible to every workflow because it's the default branch's also. ETA: yup, this works. After the first workflow run for the main branch, every other branch (in a PR) can use its cached syntest image. This fucking works!! 🚀🚀🚀 References: https://github.com/docker/buildx/blob/eab3f704f53577310c2d05700ab663f8a7ad4c8e/docs/guides/cache/gha.md#scope https://github.com/docker/buildx/blob/eab3f704f53577310c2d05700ab663f8a7ad4c8e/docs/guides/cache/gha.md#synopsis https://docs.github.com/en/actions/using-workflows/caching-dependencies-to-speed-up-workflows#matching-a-cache-key
Moved fast and broke things...
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Motivation: syntax tests in CI took 3-5 minutes, because it recompiled syntest. (The Rust compiler is well known to be slow).
By caching syntest, tests take < 20s, like the 2 regression tests. Which is nice because it's a "timeout" you can wait for, instead of going to do other things. It allows you to push & receive feedback in the same instance. Nice.
This was quite tricky to get right because I didn't RTFM in one sitting. Also there were two relevant manuals or more:
build-push-action, GitHub Actions cache, partlybuildkitand itsbuildctl... The whole ordeal is documented in the commit messages.Btw, the GitHub Actions cache is an experimental option in
build-push-action. Works for me tho. 🤷