Docker Source Hash GitHub Action

Create a hash based on Docker source files to determine if a rebuild is necessary. This action helps optimize Docker image builds by detecting changes in relevant source files and generating a unique hash, which can be used for cache keys or conditional steps in your CI/CD pipeline.

Inputs

Name	Description	Required	Default
ignore-files	List of files containing patterns to exclude from the hash generation. Each pattern should be on a new line.	false	.dockerignore
exclude-paths	List of additional path patterns to exclude from the hash generation. Each path should be on a new line.	false	(empty string)

Outputs

Name	Description
hash	The generated hash based on Docker source files.
file-list	List of files considered for hash generation.
file-count	Number of files considered for hash generation.

Usage

name: Build Docker Image
on: [push]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Generate Docker source hash
        id: hash
        uses: Matchory/docker-source-hash-action@v1
        with:
          ignore-files: |
            .dockerignore
            .gitignore
          exclude-paths: |
            node_modules/
            dist/
      - name: Use hash output
        run: |
          echo "Hash: ${{ steps.hash.outputs.hash }}"
          echo "Files: ${{ steps.hash.outputs.file-list }}"
          echo "File count: ${{ steps.hash.outputs.file-count }}"

Example Scenarios

This action is particularly useful in continuous integration pipelines where you want to avoid unnecessary Docker image rebuilds. For example, you can use the generated hash as a cache key for Docker build steps, ensuring that the build cache is only invalidated when relevant source files change.
This can significantly speed up your workflows by reusing previously built layers when possible. Additionally, you can use the hash to conditionally trigger downstream jobs or deployment steps, making your automation more efficient and reliable by only acting when actual changes to the Docker context occur.

License

MIT