Template: Docker Build GitHub Actions Workflow

A Reusable Workflow of the Docker GitHub Actions steps. Enhanced with learnings from production use.

⚠️ DO NOT call this workflow directly, rather, use it as a template repository and fork it for your own reusable workflow. I might change this workflow at anytime, based on new GHA features or learnings, and your calling workflow might break. ⚠️

Reasons to use this workflow

1. Easier to start with than hand-building all the Docker Actions into a single workflow.
2. Provides inline docs based on real-world usage of this workflow.
3. Gives you inputs so you can reuse this workflow across many repositories and only needing the full workflow stored in a central repository.
4. New in 2023: Adds SBOM and Provenance metadata to your images.
5. New in 2023: Example template to use the reusable workflow twice, in an "image promotion" style of dual registries (one for devs and PRs, one for production after PR merges)

Steps to adopt this workflow

1. Fork this repository and tweak the reusable workflow to your liking: .github/workflows/reusable-docker-build.yaml
2. Copy my "calling" workflow templates/call-docker-build.yaml to all the repositories you want to build images in and change it to point to the forked workflow above.

"But what does this workflow really do beyond just docker build?"

1. Clone the repository
2. Setup QEMU for multi-platform building (via buildx) via docker/setup-qemu-action
3. Setup buildx for awesome and fast building via docker/setup-buildx-action
4. Log into Docker Hub and/or GHCR
5. Add labels and tags via docker/metadata-action
6. Build and push image via docker/build-push-action with GitHub-based layer caching
7. Reports tags and labels in the PR comments

What other ways can I use this workflow?

I have a more advanced example of using this reusable workflow to do a "promotion" style workflow of:

1. On PR creation, build and push to a "dev" registry (GHCR)
2. On PR merge, build and push to a "prod" registry (Docker Hub)
3. Create a GitOps YAML update PR to update image tags
4. Notify of GitOps PR creation in Slack

I've added that example to my github-actions-templates repository. It calls the reusable reusable-docker-build.yaml file in this repository.

This repository is part of my example DevOps repositories on GitHub Actions

• bretfisher/github-actions-templates - Main reusable templates repository
• bretfisher/super-linter-workflow - Reusable linter workflow
• (you are here) bretfisher/docker-build-workflow- Reusable docker build workflow
• bretfisher/docker-ci-automation - Step-by-step video and example of a Docker CI workflow
• My full list of container examples and tools

More reading

• Docker Build/Push Action docs and examples
• My full list of container examples and tools

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