cabal-cache-native

This action caches the build dependencies of a Haskell project with per-package granularity. It works out of the box and it is really fast.

Usage

When building a Haskell project with cabal, cabal caches the project dependencies in a global cache called the "store". These are identified by a key that accurately represents their build configuration so they can be shared between projects.

Using @actions/cache to cache the entire store is not optimal because it would either cache the entirety of the store or nothing at all; which cabal does already at keeping track of what can be shared between builds and what can't.

The complexity of the example workflow from haskell-actions/setup is a testament to this issue.

Features

• Automatic: the action detects the project's dependencies directly from cabal's build plan and caches them automatically.
• Fast: the cache is stored in GitHub's own cache and it is restored very quickly.
• Accurate: the cached packages are identified by the same package-hash used by cabal, allowing GitHub to garbage-collect them individually when they are not needed anymore.

Usage

To use this action you need to get cabal to create a build plan (i.e. the plan.json file). This is typically achieved by passing the --dry-run flag to the build command. Once plan.json has been created, cabal-cache-native will read from it the ids of the units to restore from cache. The action will look for plan.json in ${project-path}/${plan-json}.

jobs:
  build:
    steps:
      - uses: haskell-actions/setup
        id: setup

      # ...

      # This step is required to generate the build plan
      - run: cabal build all --dry-run

      - uses: andreabedini/cabal-cache-native
        with:
          # required
          store-path: ${{ steps.setup.outputs.cabal-store }}

          # optional, the path to the project
          # project-path: .

          # optional, you can also specify the exact location of plan.json
          # plan-json: dist-newstyle/cache/plan.json

          # optional, use this to separate caches or to start from scratch.
          # cache-epoch: 0

      # No need to check for cache hits, just build your project!
      - run: cabal build all

License

You are welcome to use this under the MIT license included in the repository.