GitHub Action
Docker Image Update Checker
This action checks if a Docker image needs to be updated based on the base image it uses (e.g. FROM nginx:1.21.0). By default it checks for all platforms, but you can specify the platforms to check.
| Name | Type | Description |
|---|---|---|
base-image |
String | Base Docker Image. This is the image you have as FROM in your Dockerfile |
image |
String | Your image based on base-image |
platforms |
String | Platforms to check (default all), e.g. linux/amd64,linux/arm64 |
| Name | Type | Description |
|---|---|---|
needs-updating |
String | 'true' or 'false' if the image needs to be updated or not |
diff-images |
String | List of images (platforms) that need to be updated |
diff-json |
String | JSON output of the images (platforms) that need to be updated with the list of layers |
The action works on ubuntu and windows runners with or without a docker/login-action step. Without a login step, it will perform an anonymous pull of the manifests, except for Docker Hub because the Runners already have a token provided by GitHub (I can't find any documentation on this, but the token is there and it works).
It also works on macos runners, but because docker is not installed on the runners, you can't use the docker/login-action, so you can only use it with public images and anonymous pulls.
To authenticate with a Docker registry, you can use the docker/login-action in a step before this action.
Check if the image user/app:latest, that has nginx as a base image, needs to be updated:
name: Check docker image
on:
schedule:
- cron: '0 4 * * *'
jobs:
docker:
runs-on: ubuntu-latest
steps:
- name: Check if update available
id: check
uses: lucacome/[email protected]
with:
base-image: nginx:1.21.0
image: user/app:latest
- name: Check result
run: echo "Needs updating: ${{ steps.check.outputs.needs-updating }}"
Check if the image user/app:latest, that has nginx has a base image, needs to be updated and build and push the image if needed:
name: Check docker image
on:
schedule:
- cron: '0 4 * * *'
jobs:
docker:
runs-on: ubuntu-latest
steps:
- name: Checkout
uses: actions/[email protected]
- name: Check if update available
id: check
uses: lucacome/[email protected]
with:
base-image: nginx:1.21.0
image: user/app:latest
platforms: linux/amd64
- name: Build and push
uses: docker/[email protected]
with:
context: .
push: true
tags: user/app:latest
if: steps.check.outputs.needs-updating == 'true'Check if the image user/app:latest, that has nginx has a base image, needs to be updated for linux/amd64 and linux/arm64:
name: Check docker image for multiple platforms
on:
schedule:
- cron: '0 4 * * *'
jobs:
check:
runs-on: ubuntu-latest
outputs:
needs-updating: ${{ steps.check.outputs.needs-updating }}
steps:
- name: Login to Docker Registry
uses: docker/[email protected]
with:
username: ${{ secrets.DOCKER_USERNAME }}
password: ${{ secrets.DOCKER_PASSWORD }}
- name: Check if update available
id: check
uses: lucacome/[email protected]
with:
base-image: nginx:1.21.0
image: user/app:latest
platforms: linux/amd64,linux/arm64 # Use 'all' to check all platforms
build:
needs: check
runs-on: ubuntu-latest
if: needs.check.outputs.needs-updating == 'true'
steps:
- name: Checkout
uses: actions/[email protected]
- name: Setup QEMU
uses: docker/[email protected]
with:
platforms: arm64
- name: Docker Buildx
uses: docker/[email protected]
- name: Build and push
uses: docker/[email protected]
with:
context: .
push: true
tags: user/app:latest
platforms: linux/amd64,linux/arm64Note
The
platformsinput is optional and defaults toall.
If something is not working as expected, you can enable debug logging to get more information (a lot more information).
You can re-run the action with the Enable debug logging checkbox checked for a single run or set the ACTIONS_STEP_DEBUG secret to true in the repository's secrets.
For more information on debugging actions, see Enabling debug logging.