CI quick-reference

All CI is just bash and nix.

  • Workflow:
    • .github/workflows/ci.yml lists the jobs (default, llvm, …).
  • Scripts:
    • ci/scripts/run.sh spins up the Nix shell then calls…
    • ci/scripts/ci.sh …to configure, build, and test.
  • Configuration:
    • ci/configs/*.sh defines flags for each job.
    • shell.nix defines build environment (compilers, tools, libraries).
  • Build directories:
    • build-*/ separate build directories (like build-default, build-llvm) will be created for each job.

To run jobs locally:

CI_CONFIG=ci/configs/default.bash  ci/scripts/run.sh
CI_CONFIG=ci/configs/llvm.bash     ci/scripts/run.sh
CI_CONFIG=ci/configs/gnu32.bash    ci/scripts/run.sh
CI_CONFIG=ci/configs/sanitize.bash ci/scripts/run.sh
CI_CONFIG=ci/configs/olddeps.bash  ci/scripts/run.sh

By default CI jobs will reuse their build directories. CI_CLEAN=1 can be specified to delete them before running instead.

Running workflows with act

You can run either the entire workflow or a single matrix entry locally. On macOS or Linux:

  1. Install act and either Docker or Podman.
  2. Inside the Podman VM, create a named volume for the Nix store (ext4, case-sensitive) so builds persist across runs. Recreate it any time you want a clean cache:
podman volume create libmultiprocess-nix
  1. From the repo root, launch the workflow. The example below targets the sanitize matrix entry; drop the --matrix flag to run every configuration.
act \
  --reuse \
  -P ubuntu-latest=ghcr.io/catthehacker/ubuntu:act-24.04 \
  --container-options "-v libmultiprocess-nix:/nix" \
  -j build \
  --matrix config:sanitize