docker-metadata/README.md

About

GitHub Action to extract metadata (tags, labels) for Docker. This action is particularly useful if used with Docker Build Push action.

If you are interested, check out my other :octocat: GitHub Actions!

---

• Features
• Overview
• Usage
• Customizing
  • inputs
  • outputs
• Notes
  • Latest tag
  • tag-match examples
  • Schedule tag
  • Overwrite labels
• Keep up-to-date with GitHub Dependabot
• How can I help?
• License

Features

• Docker tags generated from GitHub action event and Git metadata
• OCI Image Format Specification used to generate Docker labels
• Handlebars template to apply to schedule tag

Overview

Event	Ref	Commit SHA	Docker Tags
schedule	refs/heads/master	45f132a	sha-45f132a, nightly
pull_request	refs/pull/2/merge	a123b57	sha-a123b57, pr-2
push	refs/heads/master	cf20257	sha-cf20257, master
push	refs/heads/my/branch	a5df687	sha-a5df687, my-branch
push tag	refs/tags/v1.2.3	bf4565b	sha-bf4565b, v1.2.3, latest

Usage

name: ci

on:
  schedule:
    - cron: '0 10 * * *' # everyday at 10am
  push:
    branches:
      - '**'
    tags:
      - 'v*.*.*'
  pull_request:

jobs:
  docker:
    runs-on: ubuntu-latest
    steps:
      -
        name: Checkout
        uses: actions/checkout@v2
      -
        name: Docker meta
        id: docker_meta
        uses: crazy-max/ghaction-docker-meta@v1
        with:
          images: name/app
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@v1
      -
        name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1
      -
        name: Login to DockerHub
        if: github.event_name != 'pull_request'
        uses: docker/login-action@v1 
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}
      -
        name: Build and push
        uses: docker/build-push-action@v2
        with:
          context: .
          file: ./Dockerfile
          platforms: linux/amd64,linux/arm64,linux/386
          push: ${{ github.event_name != 'pull_request' }}
          tags: ${{ steps.docker_meta.outputs.tags }}
          labels: ${{ steps.docker_meta.outputs.labels }}

Customizing

inputs

Following inputs can be used as step.with keys

Name	Type	Description
images	List/CSV	List of Docker images to use as base name for tags
tag-sha	Bool	Add git short SHA as Docker tag (default false)
tag-edge	Bool	Enable edge branch tagging (default false)
tag-edge-branch	String	Branch that will be tagged as edge (default repo.default_branch)
tag-match	String	RegExp to match against a Git tag and use first match as Docker tag
tag-match-group	Number	Group to get if tag-match matches (default 0)
tag-match-latest	Bool	Set latest Docker tag if tag-match matches or on Git tag event (default true)
tag-schedule	String	Template to apply to schedule tag (default nightly)
sep-tags	String	Separator to use for tags output (default \n)
sep-labels	String	Separator to use for labels output (default \n)

List/CSV type can be a newline or comma delimited string

outputs

Following outputs are available

Name	Type	Description
version	String	Generated Docker image version
tags	String	Generated Docker tags
labels	String	Generated Docker labels

Notes

Latest tag

Latest Docker tag will be generated by default on push tag event. So if for example you push the v1.2.3 Git tag, you will have at the output of this action the Docker tags v1.2.3 and latest. But you can allow the latest tag to be generated only if the Git tag matches a regular expression with the tag-match input.

tag-match examples

Git tag	tag-match	tag-match-group	Match	Docker tags
v1.2.3	\d{1,3}.\d{1,3}.\d{1,3}	0	✅	1.2.3, latest
v2.0.8-beta.67	v(.*)	1	✅	2.0.8-beta.67, latest
v2.0.8-beta.67	v(\d.\d)	1	✅	2.0, latest
release1	\d{1,3}.\d{1,3}	0	❌	release1
20200110-RC2	\d+	0	✅	20200110, latest

Schedule tag

tag-schedule is specially crafted input to support Handlebars template with the following expressions:

Expression	Example	Description
{{date 'format'}}	{{date 'YYYYMMDD'}} > 20200110	Render date by its moment format

You can find more examples in the CI workflow.

Overwrite labels

If some of the OCI Image Format Specification labels generated are not suitable, you can overwrite them like this:

      -
        name: Build and push
        uses: docker/build-push-action@v2
        with:
          context: .
          file: ./Dockerfile
          platforms: linux/amd64,linux/arm64,linux/386
          push: ${{ github.event_name != 'pull_request' }}
          tags: ${{ steps.docker_meta.outputs.tags }}
          labels: |
            ${{ steps.docker_meta.outputs.labels }}
            org.opencontainers.image.title=MyCustomTitle
            org.opencontainers.image.description=Another description
            org.opencontainers.image.vendor=MyCompany            

Keep up-to-date with GitHub Dependabot

Since Dependabot has native GitHub Actions support, to enable it on your GitHub repo all you need to do is add the .github/dependabot.yml file:

version: 2
updates:
  # Maintain dependencies for GitHub Actions
  - package-ecosystem: "github-actions"
    directory: "/"
    schedule:
      interval: "daily"

How can I help?

All kinds of contributions are welcome 🙌! The most basic way to show your support is to star 🌟 the project, or to raise issues 💬 You can also support this project by becoming a sponsor on GitHub 👏 or by making a Paypal donation to ensure this journey continues indefinitely! 🚀

Thanks again for your support, it is much appreciated! 🙏

License

MIT. See LICENSE for more details.