adding image-tag output for use in additional jobs (#26)

.github/linters/actionlint.yaml

@@ -0,0 +1,2 @@
+config-variables:
+  - SLACK_CHANNEL_ID

.github/workflows/call-local-docker-build-promotion.yaml

@@ -1,61 +0,0 @@
----
-# THIS IS NOT A TEMPLATE.
-# This is just for testing the repo itself.
-# This calls the reusable workflow from its local file path.
-name: Docker Build with Promotion
-
-on:
-  push:
-    branches:
-      - main
-    paths-ignore:
-      - 'README.md'
-      - '.github/linters/**'
-  pull_request:
-    paths-ignore:
-      - 'README.md'
-      - '.github/linters/**'
-
-# cancel any previously-started, yet still active runs of this workflow on the same branch
-concurrency:
-  group: ${{ github.ref }}-${{ github.workflow }}
-  cancel-in-progress: true
-
-permissions:
-  contents: read
-  packages: write
-  pull-requests: write
-
-jobs:
-
-  # run this job on every push to a PR
-  # it will push images to GHCR, but not DockerHub
-  docker-build-pr:
-    name: Call Build on PR
-    if: github.event_name == 'pull_request'
-    uses: ./.github/workflows/reusable-docker-build.yaml    
-    with:  
-      dockerhub-enable: false
-      ghcr-enable: true
-      push: true
-      image-names: |
-        ghcr.io/${{ github.repository }}
-
-  # run this job on every push to the default branch (including merges and tags)
-  # it will push images to GHCR and DockerHub
-  # tags will also include ones like `stable-<date>-<sha>` and `latest`
-  docker-build-merge:
-    name: Call Build on Push
-    # this if is filtered to only the main branch push event (see events at top)
-    if: github.event_name == 'push'
-    uses: ./.github/workflows/reusable-docker-build.yaml    
-    secrets:
-      dockerhub-username: ${{ secrets.DOCKERHUB_USERNAME }}
-      dockerhub-token: ${{ secrets.DOCKERHUB_TOKEN }}
-    with:  
-      dockerhub-enable: true
-      ghcr-enable: true
-      push: true
-      image-names: |
-        docker.io/${{ github.repository }}
-        ghcr.io/${{ github.repository }}

.github/workflows/reusable-docker-build.yaml

@@ -92,7 +92,6 @@ on:
         description: Build stage to target
         required: false
         type: string
-      
    
     secrets:
       dockerhub-username:
@@ -103,10 +102,9 @@ on:
         required: false
 
     outputs:
-      ghcr-tag:
+      image-tag:
-        description: "single-use tag for ghcr.io"
+        description: "single-use image tag for GHA runs"
-        value: ${{ jobs.build-image.outputs.ghcr-tag }}
+        value: ${{ jobs.build-image.outputs.image-tag }}
-
 
 # permissions: GITHUB_TOKEN are better set by the **calling** workflow
 # but we'll set defaults here for reference
@@ -126,36 +124,36 @@ jobs:
 
     outputs:
       # only outputs the unique gha- image tag that's unique to each GHA run
-      ghcr-tag: ${{ steps.ghcr-tag.outputs.tag }}
+      image-tag: ${{ steps.image-tag.outputs.image-tag }}
 
     steps:
-      -
+
         # we need qemu and buildx so we can build multiple platforms later
-        name: Set up QEMU
+      - name: Set up QEMU
         id: qemu
         uses: docker/setup-qemu-action@v2.1.0
-      -
+
         # BuildKit (used with `docker buildx`) is the best way to build images
-        name: Set up Docker Buildx
+      - name: Set up Docker Buildx
         id: buildx
         uses: docker/setup-buildx-action@v2.5.0
-      -
+
-        name: Login to DockerHub
+      - name: Login to DockerHub
         if: inputs.dockerhub-enable
         uses: docker/login-action@v2.1.0
         with:
           username: ${{ secrets.dockerhub-username }}
           password: ${{ secrets.dockerhub-token }}
-      -
+
-        name: Login to GHCR
+      - name: Login to GHCR
         if: inputs.ghcr-enable
         uses: docker/login-action@v2.1.0
         with:
           registry: ghcr.io
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
-      -
+
-        name: Docker meta
+      - name: Docker meta
         id: docker_meta
         uses: docker/metadata-action@v4.3.0
         with:
@@ -163,12 +161,12 @@ jobs:
           images: ${{ inputs.image-names }}
           flavor: ${{ inputs.flavor-rules }}
           tags: ${{ inputs.tag-rules }}
-      -
+
         # this will build the images, once per platform,
         # then push to one or more registries (based on image list above in docker_meta)
         # NOTE: this will not push if a PR is from a fork, where secrets are not available
         # https://securitylab.github.com/research/github-actions-preventing-pwn-requests/
-        name: Docker Build and Push
+      - name: Docker Build and Push
         id: build_image
         uses: docker/build-push-action@v4.0.0
         with:
@@ -189,10 +187,10 @@ jobs:
           # https://docs.docker.com/build/attestations/attestation-storage/
           provenance: true
           sbom: true
-      -
+
         # If PR, put image tags in the PR comments
         # from https://github.com/marketplace/actions/create-or-update-comment
-        name: Find comment for image tags
+      - name: Find comment for image tags
         uses: peter-evans/find-comment@v2.3.0
         if: github.event_name == 'pull_request' && inputs.comment-enable
         id: fc
@@ -220,8 +218,13 @@ jobs:
             ```
           edit-mode: replace
 
-      - name: Find the gha-run-based image tag we just pushed to ghcr.io
+        # for dependent jobs, we need to output the unique tag for this GHA run
-        id: ghcr-tag
+        # based on the docker_meta tag priority rules, the highest priority tag
+        # will be sent to this output
+        # this step output is sent to job output, which is sent to workflow output
+        # use this tag in another job with needs.<job-name>.outputs.image-tag
+      - name: Find the primary image tag we just pushed, and output it
+        id: image-tag
         run: |
           # shellcheck disable=SC2086
-          echo "tag=gha-${{ github.run_id }}" >> $GITHUB_OUTPUT
+          echo "image-tag=${{ steps.docker_meta.outputs.version }}" >> $GITHUB_OUTPUT

README.md

@@ -1,11 +1,11 @@
-# Template Repo: Docker Build and Push GitHub Actions Workflow
+# Template: Docker Build and Push GitHub Actions Workflow
 
 [![Lint Code Base](https://github.com/BretFisher/docker-build-workflow/actions/workflows/call-super-linter.yaml/badge.svg)](https://github.com/BretFisher/docker-build-workflow/actions/workflows/call-super-linter.yaml)
 [![Docker Build](https://github.com/BretFisher/docker-build-workflow/actions/workflows/call-local-docker-build.yaml/badge.svg)](https://github.com/BretFisher/docker-build-workflow/actions/workflows/call-local-docker-build.yaml)
 
 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 repo 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. ⚠️
+> ⚠️ **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
 
@@ -13,29 +13,40 @@ A Reusable Workflow of the Docker GitHub Actions steps. Enhanced with learnings
 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](https://docs.docker.com/build/attestations/) metadata to your images.
-5. New in 2023: [Example template](./templates/call-docker-build-promote.yaml) to use the reusable workflow twice, in a "image promotion" style of dual registries (one for devs and PRs, one for production after PR merges)
+5. New in 2023: [Example template](./templates/call-docker-build-promote.yaml) 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](.github/workflows/reusable-docker-build.yaml)
-2. Copy my "calling" workflow [`templates/call-docker-build.yaml`](templates/call-docker-build.yaml) to all the repos you want to build images in, and change it to point to the forked workflow above.
+2. Copy my "calling" workflow [`templates/call-docker-build.yaml`](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 (buildx) via docker/setup-qemu-action
+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
 
-## This repository is part of my example DevOps repos on GitHub Actions
+## 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](https://github.com/BretFisher/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](https://github.com/BretFisher/github-actions-templates) - Main reusable templates repository
 - [bretfisher/super-linter-workflow](https://github.com/BretFisher/super-linter-workflow) - Reusable linter workflow
 - (you are here) [bretfisher/docker-build-workflow](https://github.com/BretFisher/docker-build-workflow)- Reusable docker build workflow
-- [bretfisher/docker-ci-automation](https://github.com/BretFisher/docker-ci-automation) - Step by step video and example of a Docker CI workflow
+- [bretfisher/docker-ci-automation](https://github.com/BretFisher/docker-ci-automation) - Step-by-step video and example of a Docker CI workflow
 - [My full list of container examples and tools](https://github.com/bretfisher)
 
 ## More reading