How to Seamlessly Perform GitLab Docker Login: A Step-by-Step Guide

In today’s fast-paced development environment, automating the build and deployment of Docker images has become essential. GitLab CI/CD offers a robust solution for this, allowing developers to seamlessly integrate Docker commands within their pipelines. This guide provides a step-by-step walkthrough on how to perform GitLab Docker login, build and push Docker images, and manage your CI/CD variables securely.

Key Takeaways

  • Setting up a GitLab CI/CD pipeline involves creating a .gitlab-ci.yml file and defining stages for build, test, and deploy.
  • Authentication with GitLab Container Registry can be done using the Docker login command, and handling two-factor authentication via personal access tokens.
  • Building and pushing Docker images can be automated within GitLab CI/CD pipelines to streamline the deployment process.
  • Managing GitLab CI/CD variables securely is crucial for protecting sensitive information such as usernames and passwords.
  • Following best practices such as avoiding hardcoded credentials and regularly updating secrets ensures a secure and efficient CI/CD workflow.

Setting Up Your GitLab CI/CD Pipeline

GitLab serves as the cornerstone of our DevOps workflow. Its integrated features streamline version control, continuous integration, and continuous delivery (CI/CD). We begin our journey by defining a comprehensive pipeline in GitLab, orchestrated to automate key stages of development. This simple GitLab CI/CD pipeline consists of three stages: build, test, and deploy. The "build" stage builds the Docker image, the "test" stage utilizes Trivy for vulnerability scanning, and the "deploy" stage uses GitLab’s deployment tools.

Creating the .gitlab-ci.yml File

Let’s start by creating a .gitlab-ci.yml file in your GitLab repository. This file will serve as the blueprint for your CI/CD pipeline. Here’s a straightforward sample configuration to guide you through the initial steps.

  - build
  - test
  - deploy

  stage: build
    - docker build -t my-image:latest .

  stage: test
    - trivy image my-image:latest

  stage: deploy
    - docker push my-image:latest

Defining Pipeline Stages

Our pipeline will basically build the docker image through a Dockerfile and then push it to our Container Registry on GitLab. We will make sure we steer clear of using any keys, credentials, tokens, etc. inside our pipeline to prevent them from being stolen.

Adding Environment Variables

In your GitLab project, on the left sidebar, select Build > Pipeline editor. In the existing configuration, add the component as follows.

  • Replace <your_stage> with the stage where this job runs. It must be after the image is built and pushed to the GitLab container registry.
  - component:
      stage: <your_stage>

Once all your meticulously crafted files, from the CI/CD pipeline configuration to deployment YAMLs and beyond, are securely pushed to your GitLab repository, sit back and watch the magic unfold. GitLab will seamlessly run your pipeline, bringing your automated deployment to life. It’s the culmination of your efforts, turning code into action with the click of a button. You did it!

Authenticating with GitLab Container Registry

To push an image to GitLab’s Container Registry, you need to authenticate with the registry. You can do this by logging in to Docker with your GitLab credentials:

docker login -u your-username

Replace your-username and enter your password once prompted your-password. If you have two-factor authentication enabled, you’ll need to use a personal access token instead of your password.

Using Docker Login Command

The docker login command is your gateway to the GitLab Container Registry. Make sure to replace placeholders with your actual credentials. Here’s the basic syntax:

docker login -u <your-username> -p <your-password>

If you have two-factor authentication enabled, use a personal access token instead of your password.

Handling Two-Factor Authentication

Two-factor authentication (2FA) adds an extra layer of security. When 2FA is enabled, you can’t use your regular password for Docker login. Instead, generate a personal access token from your GitLab account settings and use it as your password.

Storing Credentials Securely

It’s crucial to store your credentials securely to avoid unauthorized access. Never hardcode your credentials in your scripts. Use GitLab CI/CD variables to store your CI_REGISTRY_USER and CI_REGISTRY_PASSWORD. This way, your credentials are kept safe and are easily accessible by your pipeline.

  CI_REGISTRY_USER: "your-username"
  CI_REGISTRY_PASSWORD: "your-password"

Always ensure your secrets are stored securely and are regularly updated to maintain security.

Building and Pushing Docker Images

Running Docker Build

Building your Docker image is the first step in the process. Use the docker build command to create an image from your Dockerfile. Ensure your Dockerfile is optimized for faster builds and smaller image sizes. This step is crucial in a CI/CD pipeline as it automates the creation of your containerized application.

Executing Docker Push

After you’ve successfully logged in, you can push your Docker image to GitLab’s Container Registry using the docker push command. Replace your-namespace, your-project, and your-image with your GitLab namespace (username or group), your GitLab project, and your Docker image name, respectively. This step ensures your image is available for deployment.

Automating with GitLab CI

GitLab CI makes it easy to automate the building and pushing of Docker images. Define your pipeline stages in the .gitlab-ci.yml file. Use the build stage to run the docker build command and the push stage to execute the docker push command. This automation is a key part of any tutorial on mastering CI/CD with GitLab: automate Docker image building, optimize containers, automate tests, manage dependencies, and leverage Docker in GitLab CI/CD pipeline.

Managing GitLab CI/CD Variables

Managing GitLab CI/CD variables is crucial for a smooth and secure pipeline. These variables help you store sensitive information, configure your pipeline, and ensure seamless integration with external services. Let’s dive into how to add and manage these variables effectively.


To start, navigate to your GitLab project settings and go to CI/CD > Variables. Here, you can add the CI_REGISTRY_USER variable. This variable should be set to your DockerHub username. This step is essential for authenticating with the GitLab Container Registry.


Next, add the CI_REGISTRY_PASSWORD variable in the same section. Set this to your DockerHub password or token. This ensures that your pipeline can log in to DockerHub without exposing your credentials directly in the pipeline script.

Using Predefined Environment Variables

GitLab offers a range of predefined environment variables that can simplify your pipeline configuration. These variables can be used to store information like registry URLs, repository names, and version numbers. Make sure to utilize these variables to keep your pipeline clean and maintainable.

Remember, using environment variables not only enhances security but also makes your pipeline more flexible and easier to manage.

Troubleshooting Common Issues

person using laptop with GitLab and Docker logos, troubleshooting code issues

Login Failures

Login failures can be frustrating, but they are often due to simple misconfigurations. Double-check your credentials and ensure that your username and password are correct. If you’re using a token, make sure it hasn’t expired. Sometimes, network issues can also cause login problems, so verify your internet connection.

Pipeline Errors

Pipeline errors can occur for various reasons, from syntax errors in your .gitlab-ci.yml file to missing dependencies. Review the pipeline logs to identify the root cause. Ensure all required services are running and accessible. If you’re stuck, consult the GitLab documentation or community forums for guidance.

Credential Problems

Credential problems often arise from incorrect or outdated information. Make sure your environment variables are set correctly and that they match the credentials stored in GitLab. Regularly update your secrets to avoid potential security risks. If you’re using a credential manager, ensure it’s properly configured and up-to-date.

Troubleshooting can be a daunting task, but with a systematic approach, you can resolve most issues quickly. Always start with the basics and work your way up to more complex solutions.

Best Practices for Secure Docker Login

Ensuring the security of your Docker login process is crucial for maintaining the integrity of your CI/CD pipeline. Here are some best practices to follow:

Avoiding Hardcoded Credentials

Never hardcode your credentials directly into your scripts or Dockerfiles. Hardcoded credentials can easily be exposed, leading to potential security breaches. Instead, use environment variables or secret management tools to handle sensitive information.

Using Personal Access Tokens

When dealing with two-factor authentication, use personal access tokens instead of passwords. Personal access tokens provide an extra layer of security and can be easily revoked if compromised. This method is especially useful when you install GitLab on Ubuntu 20.04 LTS by setting up Docker, managing as a non-root user, and ensuring security.

Regularly Updating Secrets

Regularly update your secrets and credentials to minimize the risk of unauthorized access. Set up a schedule to rotate your tokens and passwords periodically. This practice ensures that even if a credential is compromised, it won’t be valid for long.

Keeping your Docker login process secure is not just a one-time setup but an ongoing effort. Regular updates and vigilant management of credentials are key to maintaining a secure environment.

Frequently Asked Questions

What is the purpose of the .gitlab-ci.yml file?

The .gitlab-ci.yml file is used to define the structure and order of the CI/CD pipeline stages in your GitLab project. It specifies the scripts and commands to be executed during different stages like build, test, and deploy.

How do I authenticate with GitLab Container Registry?

You can authenticate with the GitLab Container Registry by using the Docker login command: `docker login -u your-username`. Replace `your-username` with your GitLab username and enter your password when prompted. If you have two-factor authentication enabled, you will need to use a personal access token instead of your password.


CI_REGISTRY_USER and CI_REGISTRY_PASSWORD are environment variables used in GitLab CI/CD pipelines to store your Docker registry username and password securely. These variables allow the pipeline to authenticate with the Docker registry without hardcoding credentials in the script.

How can I securely store Docker credentials in GitLab CI/CD?

You can securely store Docker credentials in GitLab CI/CD by adding them as environment variables in your GitLab project settings under `CI/CD` > `Variables`. This ensures that your credentials are encrypted and not exposed in your pipeline scripts.

What should I do if I encounter login failures during Docker login?

If you encounter login failures during Docker login, ensure that your username and password (or personal access token) are correct. Check if there are any typos and verify that your credentials have the necessary permissions. If you are using two-factor authentication, make sure you are using a personal access token instead of your password.

Why is it important to avoid hardcoded credentials in CI/CD pipelines?

Avoiding hardcoded credentials in CI/CD pipelines is important for security reasons. Hardcoded credentials can be exposed in your version control system, making them accessible to unauthorized users. Using environment variables and secure storage methods helps protect sensitive information and reduces the risk of security breaches.

You may also like...