Tutorial: Create a custom workspace image that supports arbitrary user IDs

In this tutorial, you’ll learn how to create a custom workspace image that supports arbitrary user IDs. You can then use this custom image with any workspace you create in GitLab.

To create a custom workspace image that supports arbitrary user IDs, you’ll:

  1. Create a base Dockerfile.
  2. Add support for arbitrary user IDs.
  3. Build the custom workspace image.
  4. Push the custom workspace image to the GitLab container registry.
  5. Use the custom workspace image in GitLab.

Prerequisites

  • A GitLab account with permission to create and push container images to the GitLab container registry
  • Docker installation

Create a base Dockerfile

To create a base Dockerfile for the container image, let’s use the Python 3.11-slim-bullseye image from Docker Hub: 

FROM python:3.11-slim-bullseye

Next, you’ll modify this base image.

Add support for arbitrary user IDs

To add support for arbitrary user IDs to the base image, let’s:

  1. Add a new gitlab-workspaces user with a 5001 user ID.
  2. Set the necessary directory permissions. 
RUN useradd -l -u 5001 -G sudo -md /home/gitlab-workspaces -s /bin/bash -p gitlab-workspaces gitlab-workspaces

ENV HOME=/home/gitlab-workspaces

WORKDIR $HOME

RUN mkdir -p /home/gitlab-workspaces && chgrp -R 0 /home && chmod -R g=u /etc/passwd /etc/group /home

USER 5001

Now that the image supports arbitrary user IDs, it’s time to build the custom workspace image.

Build the custom workspace image

To build the custom workspace image, run this command: 

docker build -t my-gitlab-workspace .

When the build is complete, you can test the image locally: 

docker run -ti my-gitlab-workspace sh

You should now be able to run commands as the gitlab-workspaces user.

Push the custom workspace image to the GitLab container registry

To push the custom workspace image to the GitLab container registry:

  1. Sign in to your GitLab account: 

    docker login registry.gitlab.com

  2. Tag the image with the GitLab container registry URL: 

    docker tag my-gitlab-workspace registry.gitlab.com/your-namespace/my-gitlab-workspace:latest

  3. Push the image to the GitLab container registry: 

    docker push registry.gitlab.com/your-namespace/my-gitlab-workspace:latest

Now that you’ve pushed the custom workspace image to the GitLab container registry, you can use the image in GitLab.

Use the custom workspace image in GitLab

To use the custom workspace image in GitLab, in your project’s .devfile.yaml, update the container image: 

schemaVersion: 2.2.0
components:
  - name: tooling-container
    attributes:
      gl/inject-editor: true
    container:
      image: registry.gitlab.com/your-namespace/my-gitlab-workspace:latest

You’re all set! You can now use this custom image with any workspace you create in GitLab.