cache

This action allows caching dependencies and build outputs to improve workflow execution time.

In addition to this cache action, other two actions are also available

Restore action

Save action

Documentation

See "Caching dependencies to speed up workflows".

What's New

v3

Added support for caching from GHES 3.5.
Fixed download issue for files > 2GB during restore.
Updated the minimum runner version support from node 12 -> node 16.
Fixed avoiding empty cache save when no files are available for caching.
Fixed tar creation error while trying to create tar with path as ~/ home folder on ubuntu-latest.
Fixed zstd failing on amazon linux 2.0 runners.
Fixed cache not working with github workspace directory or current directory.
Fixed the download stuck problem by introducing a timeout of 1 hour for cache downloads.
Fix zstd not working for windows on gnu tar in issues.
Allowing users to provide a custom timeout as input for aborting download of a cache segment using an environment variable SEGMENT_DOWNLOAD_TIMEOUT_MINS. Default is 60 minutes.
Two new actions available for granular control over caches - restore and save

Refer here for previous versions

Usage

Pre-requisites

Create a workflow .yml file in your repositories .github/workflows directory. An example workflow is available below. For more information, reference the GitHub Help Documentation for Creating a workflow file.

If you are using this inside a container, a POSIX-compliant tar needs to be included and accessible in the execution path.

Inputs

path - A list of files, directories, and wildcard patterns to cache and restore. See @actions/glob for supported patterns.
key - An explicit key for restoring and saving the cache
restore-keys - An ordered list of prefix-matched keys to use for restoring stale cache if no cache hit occurred for key.

Environment Variables

SEGMENT_DOWNLOAD_TIMEOUT_MINS - Segment download timeout (in minutes, default 60) to abort download of the segment if not completed in the defined number of minutes. Read more

Outputs

cache-hit - A boolean value to indicate an exact match was found for the key.

Note: cache-hit will be set to true only when cache hit occurs for the exact key match. For a partial key match via restore-keys or a cache miss, it will be set to false.

See Skipping steps based on cache-hit for info on using this output

Cache scopes

The cache is scoped to the key, version and branch. The default branch cache is available to other branches.

See Matching a cache key for more info.

Example workflow

name: Caching Primes

on: push

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v3

    - name: Cache Primes
      id: cache-primes
      uses: actions/cache@v3
      with:
        path: prime-numbers
        key: ${{ runner.os }}-primes

    - name: Generate Prime Numbers
      if: steps.cache-primes.outputs.cache-hit != 'true'
      run: /generate-primes.sh -d prime-numbers

    - name: Use Prime Numbers
      run: /primes.sh -d prime-numbers

Note: You must use the cache action in your workflow before you need to use the files that might be restored from the cache. If the provided key matches an existing cache, a new cache is not created and if the provided key doesn't match an existing cache, a new cache is automatically created provided the job completes successfully.

Implementation Examples

Every programming language and framework has its own way of caching.

See Examples for a list of actions/cache implementations for use with:

Creating a cache key

A cache key can include any of the contexts, functions, literals, and operators supported by GitHub Actions.

For example, using the hashFiles function allows you to create a new cache when dependencies change.

  - uses: actions/cache@v3
    with:
      path: |
        path/to/dependencies
        some/other/dependencies
      key: ${{ runner.os }}-${{ hashFiles('**/lockfiles') }}

Additionally, you can use arbitrary command output in a cache key, such as a date or software version:

  # http://man7.org/linux/man-pages/man1/date.1.html
  - name: Get Date
    id: get-date
    run: |
      echo "::set-output name=date::$(/bin/date -u "+%Y%m%d")"
    shell: bash

  - uses: actions/cache@v3
    with:
      path: path/to/dependencies
      key: ${{ runner.os }}-${{ steps.get-date.outputs.date }}-${{ hashFiles('**/lockfiles') }}

See Using contexts to create cache keys

Cache Limits

A repository can have up to 10GB of caches. Once the 10GB limit is reached, older caches will be evicted based on when the cache was last accessed. Caches that are not accessed within the last week will also be evicted.

Skipping steps based on cache-hit

Using the cache-hit output, subsequent steps (such as install or build) can be skipped when a cache hit occurs on the key. It is recommended to install the missing/updated dependencies in case of a partial key match when the key is dependent on the hash of the package file.

Example:

steps:
  - uses: actions/checkout@v3

  - uses: actions/cache@v3
    id: cache
    with:
      path: path/to/dependencies
      key: ${{ runner.os }}-${{ hashFiles('**/lockfiles') }}

  - name: Install Dependencies
    if: steps.cache.outputs.cache-hit != 'true'
    run: /install.sh

Note: The id defined in actions/cache must match the id in the if statement (i.e. steps.[ID].outputs.cache-hit)

Cache Version

Cache version is a hash generated for a combination of compression tool used (Gzip, Zstd, etc. based on the runner OS) and the path of directories being cached. If two caches have different versions, they are identified as unique caches while matching. This for example, means that a cache created on windows-latest runner can't be restored on ubuntu-latest as cache Versions are different.

Pro tip: List caches API can be used to get the version of a cache. This can be helpful to troubleshoot cache miss due to version.

Example

The workflow will create 3 unique caches with same keys. Ubuntu and windows runners will use different compression technique and hence create two different caches. And `build-linux` will create two different caches as the `paths` are different.

jobs:
  build-linux:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3

      - name: Cache Primes
        id: cache-primes
        uses: actions/cache@v3
        with:
          path: prime-numbers
          key: primes

      - name: Generate Prime Numbers
        if: steps.cache-primes.outputs.cache-hit != 'true'
        run: ./generate-primes.sh -d prime-numbers

      - name: Cache Numbers
        id: cache-numbers
        uses: actions/cache@v3
        with:
          path: numbers
          key: primes

      - name: Generate Numbers
        if: steps.cache-numbers.outputs.cache-hit != 'true'
        run: ./generate-primes.sh -d numbers

  build-windows:
    runs-on: windows-latest
    steps:
      - uses: actions/checkout@v3

      - name: Cache Primes
        id: cache-primes
        uses: actions/cache@v3
        with:
          path: prime-numbers
          key: primes

      - name: Generate Prime Numbers
        if: steps.cache-primes.outputs.cache-hit != 'true'
        run: ./generate-primes -d prime-numbers

Known practices and workarounds

Following are some of the known practices/workarounds which community has used to fulfill specific requirements. You may choose to use them if suits your use case. Note these are not necessarily the only or the recommended solution.

Windows environment variables

Please note that Windows environment variables (like %LocalAppData%) will NOT be expanded by this action. Instead, prefer using ~ in your paths which will expand to HOME directory. For example, instead of %LocalAppData%, use ~\AppData\Local. For a list of supported default environment variables, see this page.

Contributing

We would love for you to contribute to actions/cache, pull requests are welcome! Please see the CONTRIBUTING.md for more information.

License

The scripts and documentation in this project are released under the MIT License

john-shaffer/cache