GitLab CI with Docker - Mini Project: Build & Apply

GitLab CI with Docker

📖 Scenario: You are working on a project where you want to automate building a Docker image using GitLab CI. This will help you save time and avoid manual steps every time you update your code.Imagine you have a simple app and you want GitLab to build its Docker image automatically whenever you push changes.

🎯 Goal: Build a GitLab CI pipeline that uses Docker to build an image from a Dockerfile. You will create the pipeline configuration step-by-step, adding the Docker build command and finally printing the image build result.

📋 What You'll Learn

Create a basic GitLab CI YAML file named .gitlab-ci.yml

Add a job called build_image that uses the docker:latest image

Configure the job to build a Docker image named myapp:latest from the Dockerfile

Print the Docker image details after building

💡 Why This Matters

🌍 Real World

Automating Docker image builds in GitLab CI saves time and reduces errors by removing manual steps.

💼 Career

DevOps engineers and developers use GitLab CI with Docker to create reliable, repeatable build pipelines.

1

Create the GitLab CI YAML file with a build job

Create a file named .gitlab-ci.yml and add a job called build_image that uses the docker:latest image.

Docker

# Create a job called build_image using docker:latest image
# Your code here

Need a hint?

Start with the job name, then specify the image under it with proper indentation.

2

Add the script to build the Docker image

In the build_image job, add a script section with the command docker build -t myapp:latest . to build the Docker image.

Docker

build_image:
  image: docker:latest
  # Add script to build Docker image
  # Your code here

Need a hint?

Use a list under script: with a dash and the docker build command.

3

Add Docker service for Docker-in-Docker support

Add a services section to the build_image job with docker:dind to enable Docker-in-Docker during the build.

Docker

build_image:
  image: docker:latest
  script:
    - docker build -t myapp:latest .
  # Add docker:dind service below
  # Your code here

Need a hint?

Services are listed like scripts, with a dash and the service name.

4

Print the Docker image details after building

Add a command in the script section to print the details of the built image using docker images myapp:latest.

Docker

build_image:
  image: docker:latest
  services:
    - docker:dind
  script:
    - docker build -t myapp:latest .
    # Print image details below
    # Your code here

Need a hint?

Add the print command as another item in the script list.