JuliaGPU Buildkite

This repository contains resources related to the JuliaGPU Buildkite CI infrastructure:

• a custom Ubuntu-based image that can be based off of another image (e.g. CUDA's images);
• support for encrypted environment variables in the pipeline, and an environment hook to decode them;
• Docker Compose templates and systemd service files to tie everything together, and give each job a safe and reproducible execution environment.

Many of these features come from the fact that the JuliaGPU CI is intended to be run on a variety of repositories (and external PRs to those repositories), whereas Buildkite is typically used within the (trusted) boundaries of a single organization.

This README documents how to use the JuliaGPU Buildkite CI. For details on the available agents, or how to add one, see the agents README. Note that this Buildkite set-up is fairly new, and the set-up may still change. Keep an eye on this README if anything breaks.

Adding a repository

If your Julia package can use a GPU, you may use the JuliaGPU CI infrastructure to run tests on a system with a GPU. This is not a general-purpose CI service, and only intended to run GPU-related tests of Julia packages. For all other testing, use public infrastructure (Travis, Github Actions, etc).

Steps for administrators

Before everything else, the the Buildkite app needs to be available for the GitHub organization that hosts your repository. If the organization is not listed, a user with administrative privileges on both the JuliaLang BuildKite and the GitHub organization in question should set that up and make sure the organization is then listed as a repository provider. You should coordinate this on the #gpu channel of the JuliaLang slack, and ping BuildKite admins (@maleadt, @vchuravy, @DilumAluthge, ...).

Next, a BuildKite admin should set-up a pipeline for your repository:

1. Create a new pipeline, using the package's name.

   a. Under Git Repository, select the GitHub organization (if it isn't listed, the BuildKite app isn't properly set up) and the repository from the drop-down. Make sure check-out uses HTTPS.

   b. Check Auto-create webhooks.

   c. Grant permission to the JuliaGPU team.

2. Use the following steps, and click Save and Close:

   steps:
     - label: ":buildkite: Pipeline upload"
       command: buildkite-agent pipeline upload
       branches: "!gh-pages"
       agents:
         queue: "juliagpu"

3. Navigate to the Pipeline Settings.

   a. Under general settings, make the pipeline public by clicking the big green button.

   b. Under GitHub settings

   • check the box to Build pull requests from third-party forked repositories
   • check the box to Build tags
   • set the branch filter to master v* (and other branches you want to run CI for, e.g., release-*)

Steps for developers

Finally, you should create .buildkite/pipeline.yml in your repository with the steps to perform GPU CI. Start from the following template:

env:
  SECRET_CODECOV_TOKEN: "..."

steps:
  - label: "Julia v1"
    plugins:
      - JuliaCI/julia#v1:
          version: "1"
      - JuliaCI/julia-test#v1: ~
      - JuliaCI/julia-coverage#v1:
          codecov: true
    agents:
      queue: "juliagpu"
      cuda: "*"
    if: build.message !~ /\[skip tests\]/
    timeout_in_minutes: 60

If you want to perform several tests, or introduce test phases, you may want to add additional steps. Note that each step is run in a fresh container (as opposed to how Buildkite normally works), so you need to repeat the set-up that provides Julia (here done by the julia plugin) and/or instantiates your project (done by the julia-test plugin). If you need to send resources across steps, use artifacts.

For coverage submission to Codecov to work, you need to encrypt your CODECOV_TOKEN and specify it as a global SECRET_CODECOV_TOKEN (see below).

Using secrets

During start-up, agents will scan for SECRET_ environment variables and decrypt their contents for use in the rest of the pipeline. If you want to use this mechanism to provide, say, a secret CODECOV_TOKEN, run the encrypt script in this repository and follow its prompts:

$ ./tools/encrypt
Variable name: CODECOV_TOKEN
Secret value:

Use the following snippet in your pipeline.yml:

env:
  SECRET_CODECOV_TOKEN: "kaIXEN51HinaQ4JGclQcIgxeMMtXDb5uvnP3E2eKrH4Eruf2pKd5QwUGcIVL8+rcWeo5FWj883rNxRQEH3YeCWs6/i7vzs+ORvG51QeCNYQgNqFzPsWRcq5qJYc+JPFbisS7q9nghqWTwr52cnjarD4Xx3ceGorMyS5NvFpCNxMgqHNyGkLvipxcTTJfKZK61bpnbntoIjiIO1XSZKjcxnXFGFnolV9BHCr5v8f7F42n2tUH7X3nDHmTBr1AbO2lFAU9ra/KezHcIf0wg2HcV8LZD0+mj8q/SBPjQZSH7cxwx4Q2eTjT4Sw7xnrBGuySVm8ZPCAV7nRNEHo+VqR+GQ=="

If your version of OpenSSL is too old, the ./tools/encrypt script may fail. In that case, you can run it inside Docker:

docker run --rm -it -v $(pwd):/root ubuntu bash -c 'apt update && apt install -y openssl && /root/tools/encrypt'