README.md

action-check-dockerignore

Overview

This repository contains a shell script check_dockerignore.sh that checks .dockerignore against .gitignore. In other words, the ignored files by your .dockerignore should be a super set of the ignored files by your .gitignore. The purpose of it is to prevent unintended files from being sent to the build context.

Apart from the shell script, a GitHub action is defined action.yml. That means you can easily integrate the checking with GitHub Actions. See below for details.

Using this in GitHub Actions

If you build a Docker image at your project root, you can refer to this configuration.

steps:
- uses: actions/checkout@v4
- uses: oursky/action-check-dockerignore@v1
  with:
    build-context: .

If you build a Docker image at your project root, but with a custom Dockerfile, you can refer to this configuration.

steps:
- uses: actions/checkout@v4
- uses: oursky/action-check-dockerignore@v1
  with:
    build-context: .
    dockerfile: Dockerfile-custom

If your .dockerignore file is correct, this GitHub action does not output anything. If your .dockerignore file is incorrect, this GitHub action prints out a list of files that should be ignored in .dockerignore. You can review the list and amend your .dockerignore file to correct the problem.

Using this locally

When you are fixing your .dockerignore file, you may consider downloading the shell script and run it locally to iterate faster.

curl https://raw.githubusercontent.com/oursky/action-check-dockerignore/main/check_dockerignore.sh > ./check_dockerignore.sh
chmod u+x ./check_dockerignore.sh
# Run it with build-context = .
./check_dockerignore.sh check-dockerignore .