Skip to content

twiddler/is-my-docker-parent-image-out-of-date

Use this GitHub action with your project
Add this Action to an existing workflow or create a new one
View on Marketplace
 
 

Folders and files

NameName
Last commit message
Last commit date

Latest commit

 

History

58 Commits
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Repository files navigation

Is my docker parent image out-of-date?

Test

Well, ask no more! This github action has the answer! 😎

Keeping your parent image up-to-date is essential to provide your built images with the latest (security) patches. However, you might not want to stupidly rebuild your image everyday. Use this action to check if you really have to rebuild! 🥳

Works with any container registry supported by containers/skopeo. The default container registry is Docker Hub. If your image is hosted there, you can use nginx instead of docker.io/nginx. If your image is hosted on GitHub, use e.g. ghcr.io/oracle/oraclelinux8-python:3.9.

I haven't tested this with multi-stage builds, but I guess it should be able to (only) check the last stage that really makes it into your built image. Feel free to open a pull request.

Inputs

Name Type Description
parent-image String The docker parent image you are building on top
my-image String Your image which uses FROM [parent-image]

Output

Name Type Description
out-of-date String 'true' if my-image does not use the latest version of parent-image, 'false' otherwise.

Example

If you want to rebuild your image when and only when its parent image changes, you could add an action like this to your project:

name: Rebuild image when parent-image changes

# Regularly check at 4 AM
on:
  schedule:
    - cron: "0 4 * * *"

jobs:
  docker:
    runs-on: ubuntu-latest
    steps:
      # Checkout your repository. You don't need this for the check to work, but putting it here saves you an "if: ..."
      - name: Checkout
        uses: actions/checkout@v2

      # Now check if our parent image changed. The result will be available at `steps.[id of this step].outputs.out-of-date`
      - name: Check if we have to even do all this
        id: check
        uses: twiddler/is-my-docker-parent-image-out-of-date@v1
        with:
          parent-image: nginx:1.21.0
          my-image: user/app:latest

      # We only want to build and push if our parent image changed.
      - name: Build and push
        uses: docker/build-push-action@v2
        with:
          context: .
          push: true
          tags: user/app:latest
        # Add this line to all the steps you want to skip
        if: steps.check.outputs.out-of-date == 'true'

About

Let's answer that question to save some precious build time! ⌛

Resources

License

Stars

Watchers

Forks

Languages

  • Shell 85.4%
  • Dockerfile 14.6%