Continuous Deployment with Docker🐳 and Github Actions🐣

3 min readDec 25, 2020

What

Deploying Docker Images is boring. Every time you want to push your image you have to build it, give it the proper tag, authenticate with your repository, push it, and then notify your other services that a new version is available.

People shouldn’t do this work; it's designed to be automated. This will go over how to automate your Docker build process.

For the purpose of this tutorial, we will be working with Docker Hub, however, with small modifications, these will work with both GCR, ACR, or ECR.

Why

Saves developers time
Eliminates human error
Makes pipeline to production more secure

How

Pre-requisites

A Github Repository
A Docker Hub Repository

You can automate deployments with Github Actions.

Create a workflow file

Github Actions are located within the .github/workflows directory of a Github Project. For the deployment workflow we will be building, I am going to use .github/workflows/deploy-docker-image.yaml

Building the Workflow

Name

All workflows need a name, this comes in the form of the name parameter.

name: AUTO DEPLOY CONTAINER

On

The On section defines when the action will run, and when your container will get deployed.

There are two main ways to do this, depending on how you want to organize your project. The choices are between deploying the container whenever there is a push to the main branch, or whenever there is a new release.

On push to the main branch:

on:
  push:
    branches:
      - main

On release:

on:
  release:
    types: [published]

Jobs

The jobs define the work a container will have to do

jobs:
  deploy:
    runs-on: ubuntu-latest

This defines the name of the job, and where it will run. This job will be called deploy and will run on an ubuntu machine.

Steps

The steps define the work the job will have to do.

jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout Repository
        uses: actions/checkout@v2
      - name: Install Docker
        uses: docker/setup-buildx-action@v1
      - name: Login to Docker
        run: docker login --username=yourhubusername --password=***
      - name: Build Image
        env:
          IMAGE_TAG: ${{ github.sha }}
        run: docker build -t yourhubusername/imagename:$IMAGE_TAG .
      - name: Push Image
        env:
          IMAGE_TAG: ${{ github.sha }}
        run: docker push yourhubusername/imagename:$IMAGE_TAG

🥳🥳🥳 You have a working Continuous Deployment Github Action

But it can be better

Improvements

You can make it secure by using Github Secrets
You can make it more adaptable to environmental variables

Secrets

Creation

Github Secrets can be created by going to

https://github.com/username/repository/settings/secrets/actions

Note: replace username/repository with your username and repository.

You should create a secret for your password, I named mine DOCKER_HUB_PASSWORD

Using Secrets

Secrets can be used in many ways, however, I have had the most success by defining them as global environment variables, and using them as those.

Creating global environment variables

env:
   DOCKER_HUB_PASSWORD: ${{ secrets.DOCKER_HUB_PASSWORD }}
   USERNAME: yourhubusername
   REPOSITORY_NAME: yourrepositoryname

Using global environment variables

The new steps look like this:

jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout Repository
        uses: actions/checkout@v2
      - name: Install Docker
        uses: docker/setup-buildx-action@v1
      - name: Login to Docker
        run: docker login --username=yourhubusername --password=$DOCKER_HUB_PASSWORD
      - name: Build Image
        run: docker build -t $USERNAME/$REPOSITORY_NAME:$IMAGE_TAG .
      - name: Push Image
        run: docker push $USERNAME/$REPOSITORY_NAME:$IMAGE_TAG

Bonus

Create a .dockerignore file to ignore the .github folder

All code in this tutorial is available in template form here: https://github.com/theswerd/docker-githubactions