docs(instances): add GitLab runner Terraform tutorial ext-add-instances

[SIMVIA-lucas-sovre]

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Description

Added a new tutorial showing how to dynamically create and destroy GitLab runners on Scaleway instances using Terraform. This tutorial provides a cost-effective solution for teams needing high-computation runners on-demand.

Key features covered:

• Setting up Terraform configuration with Scaleway and GitLab providers
• Creating cloud-init scripts for automatic GitLab runner registration
• Implementing a complete GitLab CI/CD pipeline that provisions runners, executes jobs, and cleans up resources
• Using custom instance images for specialized use cases

Target audience: DevOps engineers and developers looking to optimize CI/CD costs by provisioning runners only when needed.

linked to the #4969 issue

[SIMVIA-lucas-sovre]

I have review all suggestions, and added almost all suggestions. Wait for the final PR validation, thanks for your help !

[SIMVIA-lucas-sovre]

@ofranc do you know when will this be merged ? or does i need to do any thing ?

[SamyOubouaziz]

Hello @SIMVIA-lucas-sovre, Sorry for the late reply! I just tested (without success), some parts of the tutorial are unclear:

• where should I create the TF and look.bash files ? at the root of the GitLab Project ?
• What to do once I created all the files to trigger the pipeline ?

[SamyOubouaziz]

at which location ? at the root of the project ?

[SamyOubouaziz]

Please Specify that it's in the project, under Settings > CI/CD > Variables

[SamyOubouaziz]

If required, add a step to describe what to do to trigger the pipeline, and how to see the logs of the jobs to check if everything works fine. Thanks!

[SamyOubouaziz]

Also, another technical writer tested it before, and got the error below

╷
│ Error: Error creating new GitLab Runner
│
│   with gitlab_user_runner.project_runner,
│   on main.tf line 50, in resource "gitlab_user_runner" "project_runner":
│   50:         resource "gitlab_user_runner" "project_runner" {
│
│ couldn't create new GitLab Runner: POST https://gitlab.com/api/v4/user/runners: 400 {message: 400 Bad
│ request - Tags list can not be empty when runner is not allowed to pick untagged jobs}

Could you check if you can reproduce and fix accordingly if there is an issue with your code?

Thank you very much !