Merge branch 'docs/add-gke-via-iac-instructions' into 'master'

Adds instructions on how to set up GKE - only docs

See merge request gitlab-org/gitlab!64654

doc/user/infrastructure/clusters/connect/new_gke_cluster.md

+---
+stage: Configure
+group: Configure
+info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
+---
+
+# New GKE cluster through IaC
+
+Learn how to create a new cluster on Google Kubernetes Engine (GKE) through
+[Infrastructure as Code (IaC)](../../index.md).
+
+This process combines the GitLab Terraform and Google Terraform providers
+with Kubernetes to help you create GKE clusters and deploy them through
+GitLab.
+
+This document describes how to set up a [group-level cluster](../../../group/clusters/index.md) on GKE by importing an example project to get you started.
+You can then modify the project files according to your needs.
+
+**Prerequisites:**
+
+- A GitLab group.
+- A GitLab user with maintainer permissions to the group.
+- A [GitLab personal access token](../../../profile/personal_access_tokens.md) with `api` access, created by a user with maintainer permissions to the group.
+- A [Google Cloud Platform (GCP) service account](https://cloud.google.com/docs/authentication/getting-started).
+
+**Steps:**
+
+1. [Import the example project](#import-the-example-project).
+1. [Add your GCP credentials to GitLab](#add-your-gcp-credentials-to-gitlab).
+1. [Configure your project](#configure-your-project).
+1. [Deploy your cluster](#deploy-your-cluster).
+
+## Import the example project
+
+Start by [importing the example project by URL](../../../project/import/repo_by_url.md). Use `https://gitlab.com/gitlab-org/configure/examples/gitlab-terraform-gke.git` as URL.
+
+## Add your GCP credentials to GitLab
+
+After importing the project, you need to set up [CI environment variables](../../../../ci/variables/index.md) to associate your cluster on GCP to your group in GitLab.
+
+We advise that you [set environment variables through the GitLab UI](../../../../ci/variables/index.md#add-a-cicd-variable-to-a-project)
+so that your credentials are not exposed through the code. To do so, follow the steps below.
+
+### Prepare your credentials on GCP
+
+1. Create a [GCP service account](https://cloud.google.com/docs/authentication/getting-started) to authenticate GCP with GitLab. It needs the following roles: `Computer Network Viewer`, `Kubernetes Engine Admin`, and `Service Account User`.
+1. Download the JSON file with the service account key.
+1. On your computer, encode the JSON file to `base64` (replace `/path/to/sa-key.json` to the path to your key):
+
+   ```shell
+   base64 /path/to/sa-key.json | tr -d \\n`
+   ```
+
+1. Use the output of this command as the `BASE64_GOOGLE_CREDENTIALS` environment variable in the next step.
+
+### Add your credentials to GitLab as environment variables
+
+1. On GitLab, from your project's sidebar, go to **Settings > CI/CD** and expand **Variables**.
+1. Add your `GITLAB_TOKEN` ([personal access token](../../../profile/personal_access_tokens.md)).
+1. Add the variable `BASE64_GOOGLE_CREDENTIALS` from the previous step.
+
+## Configure your project
+
+After authenticating with GCP, replace the project's defaults from the example
+project with your own. To do so, edit the files as described below.
+
+Edit `gke.tf`:
+
+1. **(Required)** Replace the GCP `project` with a unique project name.
+1. **(Optional)** Choose the `name` of your cluster.
+1. **(Optional)** Choose the `region` and `zone` that you would like to deploy your cluster to.
+1. Push the changes to your project's default branch.
+
+Edit `group_cluster.tf`:
+
+1. **(Required)**: Replace the `full_path` with the path to your group.
+1. **(Optional)**: Choose your cluster base domain through `domain`.
+1. **(Optional)**: Choose your environment through `environment_scope`.
+1. Push the changes to your project's default branch.
+
+Refer to the [GitLab Terraform provider](https://registry.terraform.io/providers/gitlabhq/gitlab/latest/docs) and the [Google Terraform provider](https://registry.terraform.io/providers/hashicorp/google/latest/docs/guides/provider_reference) documentation for further resource options.
+
+## Deploy your cluster
+
+After adjusting the files in the previous step, manually trigger the deployment of your cluster. In GitLab:
+
+1. From your project's sidebar, go to **CI/CD > Pipelines**.
+1. Select the dropdown icon (**{angle-down}**) next to the play icon (**{play}**).
+1. Select **deploy** to manually trigger the deployment job.
+
+When the pipeline finishes successfully, you can see your new cluster:
+
+- In GCP: on your [GCP console's Kubernetes list](https://console.cloud.google.com/kubernetes/list).
+- In GitLab: from your project's sidebar, select **Infrastructure > Kubernetes clusters**.

doc/user/infrastructure/index.md

@@ -101,3 +101,7 @@ owned by GitLab, where everyone can contribute.
 
 The [documentation of the provider](https://registry.terraform.io/providers/gitlabhq/gitlab/latest/docs)
 is available as part of the official Terraform provider documentations.
+
+## Create a new cluster through IaC
+
+Learn how to [create a new cluster on Google Kubernetes Engine (GKE)](clusters/connect/new_gke_cluster.md).