add guide for Terraform (#624)

Author: Katie Horne

guides/deployments/terraform.md

@@ -0,0 +1,56 @@
+---
+title: Terraform
+description: Learn how to deploy Coder using Terraform.
+---
+
+Coder offers [Terraform modules](https://github.com/cdr/enterprise-terraform)
+that help you deploy Coder faster.
+
+Currently, we offer a single-command deployment of Coder to Google Cloud
+Platform. We will add support for additional cloud providers in the future.
+
+## Deploying Coder to Google Cloud Platform
+
+> Before proceeding, please make sure that you have both
+> [Terraform](https://www.terraform.io/downloads.html) and
+> [Terragrunt](https://terragrunt.gruntwork.io/docs/getting-started/quick-start/)
+> installed.
+
+1. [Copy the GKE example](https://github.com/cdr/enterprise-terraform/tree/main/examples/gke/self-hosted)
+   to the location of your choice (we recommend version controlling the entire
+   folder).
+
+1. [Create a cloud DNS zone](https://cloud.google.com/dns/docs/quickstart)
+   containing your desired hostname. This must be in the same GCP project where
+   you will deploy Coder.
+
+1. Update the `terragrunt.hcl` file that's included in the root of your example
+   folder. The `terragrunt.hcl` file contains notes that will guide you through
+   customization options available. When done, you can view the changes you
+   proposed running:
+
+   ```console
+   terragrunt run-all plan
+   ```
+
+   If you run the above command and it fails, you may have misconfigured one or
+   more of the variables required. The output will direct you to the problematic
+   areas.
+
+1. Deploy Coder by running:
+
+   ```console
+   terragrunt run-all apply
+   ```
+
+   If the `apply` command succeeds, you will be able to access Coder at the
+   hostname you provided. Log in with `admin` as the username and the password
+   that you're provided.
+
+## Tear down
+
+To tear down your Coder deployment, run:
+
+```console
+terragrunt run-all destroy
+```

manifest.json

@@ -360,6 +360,9 @@
             },
             {
               "path": "./guides/deployments/teardown.md"
+            },
+            {
+              "path": "./guides/deployments/terraform.md"
             }
           ]
         },