Add rules_haskell to regression-checked bazel projects

[Profpatsch]

Bazel has ~50 repositories it auto-checks for regressions on their CI for every release: https://buildkite.com/bazel/bazel-at-head-plus-downstream/builds/821

We should make an effort to get rules_haskell in that list.

[jin]

You can start here 😄 https://github.com/bazelbuild/continuous-integration/issues/new?assignees=&labels=new-project&template=adding-your-project-to-bazel-ci.md&title=Request+to+add+new+project+%5BPROJECT_NAME%5D

[laurentlb]

Yes, it would be great to have it.
(I filed the same issue some time ago: bazelbuild/continuous-integration#235)

[Profpatsch]

We moved our start script to GHC bindists yesterday, meaning the runner won’t have to have nix installed for a simple setup check. I think we are ready to add at least a simple regression check to the upstream pipeline.

Since we also merged hazel, we should be able to get rid of the nix requirement for most of our basic testing setup soon.

I don’t know if I can find the time to do this soon, but @laurentlb if you are interested I’ll gladly help with any questions you have.

[laurentlb]

What is the status of this? Is there any blocker?

@fweikert may be able to help you with Buildkite integration.

[Profpatsch]

Most of our tests still depend on nix, but we could start by only enabling a subset of them in the Buildkite config.
Alternatively, the CI machine would have to have nix installed.

[philwo]

I haven't used nix myself yet, is it difficult to install? If it's just a matter of installing it in our Docker image, that shouldn't be a problem.

[Profpatsch]

Actually, we recently switched to a non-nix setup for our tests, by adding a repository rule to install things with the stack tool instead. So no additional provisioning of the build machine should be necessary.

[mboes]

@philwo Nix is no longer required. Have a look at the CircleCI config (.circleci/config.yaml) and the build-linux-ghc-bindist job in particular. That job assumes Bazel is in the Docker image along with a small set of other system dependencies that you probably already have, and is able to run a core part of the full rules_haskell test suite while assuming nothing else from the environment. We do disable a few tests, however. See --build_tag_filters line.

[Profpatsch]

#1066 added us to the official upstream pipeline, and a few of our maintainers got access to https://buildkite.com/bazel/rules-haskell-haskell.

The next step is getting rules_haskell to actually build on the upstream buildkite, then they will add us to their downstream testing pipeline.

[Profpatsch]

@fweikert The CI is currently failing because we need the libgmp-dev apt package installed for GHC to work. Is there a way to add it to the build description yaml? cc @laurentlb @philwo

Related, is there documentation of how the .bazelci file format works?

[fweikert]

We have to deploy the libgmp-dev package to our CI workers.

Configuration documentation: https://github.com/bazelbuild/continuous-integration/blob/master/buildkite/README.md#basic-syntax

[Profpatsch]

We have to deploy the libgmp-dev package to our CI workers.

Great, can you ping us here once that is done? We’d really like this ruleset to be downstream-checked before 1.0 is out.

[fweikert]

I'll do!

[philwo]

@Profpatsch @fweikert I added the libgmp-dev package to our ubuntu1604, ubuntu1804 and debian10 environments and pushed the new containers, so it should be effective immediately.

[Profpatsch]

bazelbuild/continuous-integration#235 (comment)

@laurentlb We have a successful build on the CI now: tweag/rules_haskell#1099 (CI log: https://buildkite.com/bazel/rules-haskell-haskell/builds/109)

I think we’re ready to be added to your list of downstream projects.

cc @philwo @fweikert @mboes

[aherrmann]

AFAIU this is done.