A shortcut action to cache Julia depot contents to reduce GitHub Actions running time.

An example workflow that uses this action might look like this:

name: CI

on: [push, pull_request]

# needed to allow julia-actions/cache to delete old caches that it has created
permissions:
  actions: write
  contents: read

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v4
    - uses: julia-actions/setup-julia@v2
    - uses: julia-actions/cache@v2
    - uses: julia-actions/julia-buildpkg@v1
    - uses: julia-actions/julia-runtest@v1

By default all depot directories called out below are cached.

• jq: This action uses jq to parse JSON. For GitHub-hosted runners, jq is installed by default. On self-hosted runners and custom containers, if jq is not already available, this action will automatically use dcarbone/install-jq-action to install jq (Note: dcarbone/install-jq-action requires that curl is installed; this may not always be the case in custom containers and self-hosted runners).
• bash: This action requires bash. For GitHub-hosted runners bash is installed by default. Self-hosted runners will need to ensure that bash is installed and available on the PATH.

• cache-name - The cache key prefix. Defaults to julia-cache;workflow=${{ github.workflow }};job=${{ github.job }}. The key body automatically includes the OS and, unless disabled with include-matrix, the matrix vars. Include any other parameters/details in this prefix to ensure one unique cache key per concurrent job type.
• include-matrix - Whether to include the matrix values when constructing the cache key. Defaults to true.
• depot - Path to a Julia depot directory where cached data will be saved to and restored from. Defaults to the first depot in JULIA_DEPOT_PATH if specified. Otherwise, defaults to ~/.julia.
• cache-artifacts - Whether to cache the depot's artifacts directory. Defaults to true.
• cache-packages - Whether to cache the depot's packages directory. Defaults to true.
• cache-registries - Whether to cache the depot's registries directory. Defaults to true.
• cache-compiled - Whether to cache the depot's compiled directory. Defaults to true.
• cache-scratchspaces - Whether to cache the depot's scratchspaces directory. Defaults to true.
• cache-logs - Whether to cache the depot's logs directory. Defaults to true. Helps auto-Pkg.gc() keep the cache small.
• delete-old-caches - Whether to delete old caches for the given key. Defaults to true.
• token - A GitHub PAT. Defaults to github.token. Requires repo scope to enable the deletion of old caches.

• cache-hit - A boolean value to indicate an exact match was found for the primary key. Returns "" when the key is new. Forwarded from actions/cache.

This action is a wrapper around https://github.com/actions/cache. In summary, this action stores the files in the aforementioned paths in one compressed file when running for the first time. This cached file is then restored upon the second run, and afterwards resaved under a new key, and the previous cache deleted. The benefit of caching is that downloading one big file is quicker than downloading many different files from many different locations and precompiling them.

By default, this action removes caches that were previously made by jobs on the same branch with the same restore key. GitHub automatically removes old caches after a certain period or when the repository cache allocation is full. It is, however, more efficient to explicitly remove old caches to improve caching for less frequently run jobs.

The cache key that the cache will be saved as is based on:

• The cache-name input
• All variables in the matrix (unless disabled via include-matrix: 'false')
• The runner.os (may be in the matrix too, but included for safety)
• The run id
• The run attempt number

This action automatically deletes old caches that match the first 4 fields of the above key:

• The cache-name input
• All variables in the matrix (unless disabled via include-matrix: 'false')
• The runner.os (may be in the matrix too, but included for safety)

Which means your caches files will not grow needlessly. GitHub also deletes cache files after 7 days of not being accessed, and there is a limit of 10 GB for the total size of cache files associated to each repository.

permissions:
  actions: write
  contents: read

To disable deletion set input delete-old-caches: 'false'.

Caches are restored and re-saved after every run, retaining the state of the depot throughout runs. Their size will be regulated like a local depot automatically by the automatic Pkg.gc() functionality that clears out old content, which is made possible because the /log contents are cached.

This action is built around actions/cache and includes parts of that action. actions/cache has been released under the following licence:

The MIT License (MIT)

Copyright (c) 2018 GitHub, Inc. and contributors

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.