Automating Review Apps Deployment in GitLab

Deploying a Review App for merge requests in GitLab typically involves setting up an environment where a version of the application can be built and tested based on the code submitted in a merge request. Pulumi can help automate the infrastructure required for such a Review App.

Below, you'll find a Pulumi program written in TypeScript that demonstrates how you could set up a GitLab project with the necessary configurations to enable a Review App for merge requests. This example assumes that you already have GitLab set up and will focus on creating a new project with Pulumi, along with the required resources for the Review App.

Here's a step-by-step guide:

Project Creation: The program will start by creating a new GitLab project using the gitlab.Project resource. The project serves as the container for your codebase and the Review App's infrastructure.
Branch and Environment: Once the project is set up, we'll create a branch for the environment using the gitlab.Branch resource. Then, we'll create an environment with gitlab.ProjectEnvironment within the project, which will represent our Review App's environment.
Runner Configuration: Although not explicitly managed in the example program, you would use gitlab.ProjectRunnerEnablement to tie a specific GitLab Runner to your project. Runners are used to execute your CI/CD pipelines. A predefined runner needs to exist or be created manually in GitLab for this purpose.
Approval Configuration: Optionally, you can also set up approval rules using gitlab.ProjectApprovalRule, enforcing certain quality or review checks before merges can occur.

After this initial setup, you'll configure your .gitlab-ci.yml pipeline to deploy your application to this environment every time a merge request is opened. This part occurs outside of Pulumi and directly in your repository in the form of a CI/CD pipeline code.

Let's see how the Pulumi program in TypeScript might look:

import * as pulumi from "@pulumi/pulumi";
import * as gitlab from "@pulumi/gitlab";

const projectName = "review-app-project";

// Create a GitLab project.
const project = new gitlab.Project(projectName, {
    name: projectName,
    description: "Project to demonstrate Review Apps in GitLab",
    visibilityLevel: "private",
});

// Add a branch for review apps.
const reviewBranch = new gitlab.Branch("review-branch", {
    project: project.id,
    name: "review-apps",
    ref: "master", // Assuming 'master' is the default branch.
});

// Add an environment for review apps.
const reviewAppEnv = new gitlab.ProjectEnvironment("review-app-environment", {
    project: project.id,
    name: "review-apps",
});

// Output the project and environment URLs.
export const projectUrl = project.webUrl;
export const reviewAppEnvironmentUrl = pulumi.interpolate`${project.webUrl}/environments/${reviewAppEnv.id}`;

This program does the following:

Defines a new GitLab project where your code will be hosted and where merge requests will be created.
Creates a new branch that will be used specifically for Review Apps.
Sets up an environment in GitLab to host each Review App instance.

Please note that in a real-world scenario, additional resources like databases, Kubernetes clusters, or VMs might be required, depending on where and how you want to host your Review App. Also, setting up the actual runner and CI/CD pipeline code is not covered in this Pulumi program and would need to be handled separately within GitLab.

Remember to run pulumi up in the terminal within the Pulumi project directory to deploy this infrastructure.

For comprehensive documentation on the GitLab provider and its resources in Pulumi, you can visit the following links:

This program is just the starting point, and you would need to adapt it to fit the specific requirements of your Review App setup.