Creating a Docker GitLab Runner

Ever wondered how to set up your own GitLab Runner using Docker. Let's dive in!

Step 1: Prerequisites

Before we begin, make sure you have Docker installed on your system. You can download and install Docker from the official website.

www.docker.com

Step 2: Get GitLab Runner Registration Token

To register your GitLab Runner, you'll need a registration token from your GitLab instance. This can be done at Group level if you wanna use shared runners or at Project level if you want a runner that's project specific.

Lets use the Group level.

Log in to your GitLab account.

Navigate to your group where you want to register the runner.

Go to Build > Runners in the left sidebar.

Click New Group Runner

Copy the registration token , you'll need this for the config.toml file.

Step 3: Update the config.toml File

Now, let's update the config.toml file with your GitLab registration details. Open the config.toml file and replace the placeholders with your actual GitLab Runner details:

[[runners]]
  name = "example-name"
  url = "https://gitlab.com"
  token = "registration-token"
  executor = "docker"
  [runners.docker]
    image = "alpine:latest"
    privileged = false
    disable_entrypoint_overwrite = false
    oom_kill_disable = false
    disable_cache = false
    volumes = ["/cache"]
    shm_size = 0        

Step 4: Build the Docker Image

Next, let's build the Docker image using the provided Dockerfile and config.toml file.

# Use an existing GitLab Runner image as the base
FROM gitlab/gitlab-runner:latest

# Copy the custom config.toml file into the container
COPY config.toml /etc/gitlab-runner/config.toml        

Open your terminal and navigate to the directory containing these files. Then, run the following command:

docker build -t gitlab-runner .        

Step 6: Using the Runner

That's it! You're all set up. Now you can use your GitLab Runner to automate your CI/CD pipelines.