Add new project root module for measurement-lab (#69)

* Adds google.visualizations provider alias to mlab-oti main.tf

We aren't currently using the visualizations module anywhere in the mlab-oti
configuration. However, TF's documentation makes it sound like you should
always list all configuration aliases in the required_providers section, which
is shared between all projects. If you add the alias to the
configuration_aliases list, but don't declare it in the module, TF will emit an
error.

* Adds new project root module for measurement-lab

As a start, it adds the visualizations module, since the public Grafana
instance will run in that project.

* Adds provider alias defs for platform-cluster and visualizations

versions.tf is shared between all projects, and in that file any
configuration_aliases that are listed, must be defined in the root module, even
if those aliases are not used.

measurement-lab/main.tf

@@ -0,0 +1,32 @@
+terraform {
+  backend "gcs" {
+    # Terraform does not allow variable interpolation in backend blocks.
+    bucket = "terraform-support-measurement-lab"
+    prefix = "state"
+  }
+}
+
+provider "google" {
+  project = "measurement-lab"
+}
+
+provider "google" {
+  alias   = "platform-cluster"
+  project = "measurement-lab"
+  region  = "us-central1"
+  zone    = "us-central1-a"
+}
+
+provider "google" {
+  alias   = "data-pipeline"
+  project = "measurement-lab"
+  region  = "us-central1"
+  zone    = "us-central1-a"
+}
+
+provider "google" {
+  alias   = "visualizations"
+  project = "measurement-lab"
+  region  = "us-central1"
+  zone    = "us-central1-a"
+}

measurement-lab/versions.tf

@@ -0,0 +1 @@
+../versions.tf

measurement-lab/visualizations.tf

@@ -0,0 +1,7 @@
+module "visualizations" {
+  source = "../modules/visualizations"
+
+  providers = {
+    google = google.visualizations
+  }
+}

mlab-autojoin/main.tf

@@ -16,3 +16,17 @@ provider "google" {
   region  = "us-central1"
   zone    = "us-central1-a"
 }
+
+provider "google" {
+  alias   = "platform-cluster"
+  project = "mlab-autojoin"
+  region  = "us-central1"
+  zone    = "us-central1-a"
+}
+
+provider "google" {
+  alias   = "visualizations"
+  project = "mlab-autojoin"
+  region  = "us-central1"
+  zone    = "us-central1-a"
+}

mlab-oti/main.tf

@@ -23,3 +23,10 @@ provider "google" {
   region  = "us-central1"
   zone    = "us-central1-a"
 }
+
+provider "google" {
+  alias   = "visualizations"
+  project = "mlab-oti"
+  region  = "us-central1"
+  zone    = "us-central1-a"
+}

versions.tf

@@ -5,7 +5,8 @@ terraform {
       version = "5.12.0"
       configuration_aliases = [
         google.data-pipeline,
-        google.platform-cluster
+        google.platform-cluster,
+        google.visualizations
       ]
     }
   }