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
  • Coerces Git tag
  • Schedule tag
• 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/<default_branch>	676cae2	sha-676cae2, edge
push	refs/heads/dev	cf20257	sha-cf20257, dev
push	refs/heads/my/branch	a5df687	sha-a5df687, my-branch
push tag	refs/tags/v1.2.3	bf4565b	sha-bf4565b, 1.2.3, latest
push tag	refs/tags/mytag	afb7833	sha-afb7833, mytag

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
            ghcr.io/name/app            
          tag-sha: true
      -
        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-coerce-tag	String	Coerces Git tag to semver if possible using Handlebars template
tag-latest-match	String	Set latest tag only if matches with a pattern
tag-schedule	String	Handlebars 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 tag is created with the following conditions:

• Git tag is a valid semver
• Provided tag-coerce-tag is valid

If tag-latest-match is filled, then it has priority over the creation of the tag.

Coerces Git tag

Provides a very forgiving translation of a non-semver tag to semver. For more information see Coercion section. tag-coerce-tag supports Handlebars template with the following inputs:

tag-coerce-tag	Git tag	Version
{{raw}}	v1.2.3	1.2.3
{{major}}.{{minor}}	v1.2.3	1.2
{{major}}	v1.2.3	1
{{minor}}	v1.2.3	2
{{patch}}	v1.2.3	3

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.

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.