Pushing Docker images using GitHub Actions can streamline your deployment process. In this guide, we’ll show you how to push a Docker image to Docker Hub using GitHub Actions, step by step. You can also find a detailed example by visiting the GitHub repository here.
Before we start I assume that you have a basic understanding of Docker and Github.

What is GitHub actions:

GitHub Actions enables the user to create custom Software Development Life Cycle (SDLC) workflows in their GitHub repositories. It gives a privilege to the repository owner to write individual actions and then combine
them to create a custom workflow of their choice for their project. GitHub Actions also provides the facility to build end-to-end Continuous Integration (CI) and Continuous Deployment (CD) capabilities directly in the repository.

Let us take an example of how GitHub Action can be implemented in a simple repository.

Step 1

• Create a new repository

Create Dockerfile

nano Dockerfile

Paste this code in Dockerfile

FROM python:3.6ENV PYTHONDONTWRITEBYTECODE 1

ENV PYTHONUNBUFFERED 1

WORKDIR /code

ADD . /code

RUN pip install -r requirements.txt

CMD ["python", "app.py"]

Then create app.py and paste this code below

from flask import Flaskapp = Flask(__name__)@app.route('/')

def home():
    return 'Home Page' 

if __name__ == "__main__":
    app.run(host="0.0.0.0", port=8070, debug=False)

now let’s create a requirements.txt file to install the required python packages

nano requirements.txt

And also paste this code below.

flask=2.0.2

To make sure everything is working perfectly, run the following command.

$ docker build -t  push-docker-image:latest .

then

docker run -d  -p 8070:8070 push-docker-image:latest

Now check on the web browser

Step 2

Now I’ll create GitHub actions config file

1. Create a .github/workflows folder.

mkdir -p .github/workflows

1. and inside workflows folder create a .yml file, (eg push-docker-image.yaml)

touch .github/workflows/push-docker-image.yaml

Paste this code into your .yml file

name: Workflow Title
on:
  push

env:
  DOCKER_USER: ${{ secrets.DOCKER_USER }}
  DOCKER_PASSWORD: ${{ secrets.DOCKER_PASSWORD }}
  REPO_NAME: ${{ secrets.REPO_NAME }}

jobs:
  push-image-to-docker-hub:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2

      - name: Docker Login
        run: |
          docker login -u $DOCKER_USER -p $DOCKER_PASSWORD

      - name: Get Current Date
        id: date
        run: echo "::set-output name=date::$(date +'%Y-%m-%d--%M-%S')"

      - name: Build Docker Image
        run: docker build . --file Dockerfile --tag $DOCKER_USER/$REPO_NAME:${{ steps.date.outputs.date }}

      - name: Push Docker Image
        run: docker push $DOCKER_USER/$REPO_NAME:${{ steps.date.outputs.date }}

After pushing the code to GitHub, go to the Actions section, you will find the workflow you created, you will receive an error because those variables DOCKER_USER and DOCKER_PASSWORD and REPO_NAME are not set.

In order to fix that, go to settings –> secrets and create tree secrets (DOCKER_USER & DOCKER_PASSWORD, REPO_NAME), re-push an update and go back to the actions section you will now see a green circle witch means the workflow was completed successfully.

Now go to docker hub you will find an image with a tag similar to YYYY-M-D--m-s.

congratulation we have successfully pushed an image to the docker hub.

Resources

• https://docs.github.com/en/actions
• https://www.beopenit.com/github-actions-le-nouveau-pipeline-ci-cd-de-github/

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