feat: improve Cloud Run deployment template

docs/deployment/gcloud/README.md

@@ -1,19 +1,55 @@
 # Google Cloud Run Deployment
 
+## Overview
+
+This example provides a basic Terraform project to deploy the playground
+on Google Cloud as a [Cloud Run](https://cloud.google.com/run?hl=en) app.
+
+HCL defines:
+
+* Cloud Run service with the app.
+* Simple bucket with shared Go mod and WASM builds cache.
+* IAM rules for a cache bucket.
+
 ## Prerequisites
 
 * [Terraform](https://www.terraform.io/) or [OpenTofu](https://opentofu.org).
-* [gcloud](https://cloud.google.com/sdk/docs/install) tool.
+* [Google Cloud CLI (`gcloud`)](https://cloud.google.com/sdk/docs/install).
 * [Google Cloud](https://cloud.google.com/) project.
 
-## Setup
+## Deployment
+
+### First-time setup
+
+Initialize a Terraform project and prepare a TF variables file:
 
-* Initialize project using `terraform init` command.
-* Copy `example.tfvars` to `prod.tfvars` and edit the file.
-* Prepare Terraform plan using variables file: \
-    `terraform plan -var-file="prod.tfvars" -out=tfplan`
-* Apply a plan using `terraform apply tfplan` command.
+```shell
+# Auth on gcloud and init TF project.
+# This action should be called only once.
+make init
 
-## Configuration
+# Create a var file from a template
+# and fill it with correct values:
+cp example.tfvars prod.tfvars
+vim prod.tfvars
+```
+
+### App Configuration
 
 See environment variables section in [Docker](../docker/README.md) docs.
+
+### Deploying changes
+
+```shell
+# Prepare a Terraform plan
+make plan
+
+# Apply a plan
+make apply
+```
+
+### Destroying a deployment
+
+```shell
+make destroy
+```

docs/deployment/gcloud/main.tf

@@ -1,28 +1,110 @@
-# See: https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/cloud_run_v2_service 
-
-# Beta provider is required for "empty_dir" storage type.
+# Beta provider is required for "gcs" storage type.
 provider "google-beta" {
   project = var.project_id
   region  = var.region
 }
 
+# By default, TF will keep infra state in '*.tfstate' files.
+# Uncomment this block if you with to keep TF state in a storage bucket:
+#terraform {
+#  backend "gcs" {
+#    bucket = "<YOUR BUCKET NAME>"
+#    prefix = "tfstates"
+#  }
+#}
+
+locals {
+  cache_bucket_name = "gpg-build-cache-${var.app_env}"
+  cache_bucket_mount = "/mnt/gpg-build-cache-${var.app_env}"
+  service_account_id = "gpg-svc-acc-${var.app_env}"
+}
+
+# Service account to access playground's cache bucket.
+#
+# See: https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/google_service_account
+resource "google_service_account" "run_sa" {
+  account_id   = local.service_account_id
+  project = var.project_id
+  display_name = "Service Account for a Better Go Playground (${var.app_env})"
+}
+
+# Bucket to keep cached WASM builds and downloaded Go modules.
+#
+# See: https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/storage_bucket
+resource "google_storage_bucket" "static" {
+  project = var.project_id
+  location = var.region
+  name = local.cache_bucket_name
+  public_access_prevention = "enforced"
+
+  # Truncate Go module cache policy
+  lifecycle_rule {
+    condition {
+      age = 14
+      matches_prefix = ["mod/"]
+    }
+
+    action {
+      type = "Delete"
+    }
+  }
+
+  # Truncate WASM builds cache policy
+  lifecycle_rule {
+    condition {
+      age = 7
+      matches_prefix = ["builds/"]
+    }
+
+    action {
+      type = "Delete"
+    }
+  }
+
+  # Truncate incomplete uploads
+  lifecycle_rule {
+    condition {
+      age = 1
+    }
+    action {
+      type = "AbortIncompleteMultipartUpload"
+    }
+  }
+}
+
+# IAM rule to grant access for a cache bucket.
+#
+# See: https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/storage_bucket_iam
+resource "google_storage_bucket_iam_binding" "bucket_access" {
+  bucket = google_storage_bucket.static.name
+  role   = "roles/storage.objectAdmin"
+  members = [
+    "serviceAccount:${google_service_account.run_sa.email}"
+  ]
+}
+
+# The app service.
+#
+# See: https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/cloud_run_v2_service 
 resource "google_cloud_run_v2_service" "default" {
   provider = google-beta
   name     = "gpg-${var.app_env}"
   location = var.region
   launch_stage = "BETA"
 
   template {
+    # Use service account with cache bucket access
+    service_account = google_service_account.run_sa.email
+
     scaling {
       min_instance_count = 1
       max_instance_count = 5
     }
 
     volumes {
-      name = "gpg-build-cache-${var.app_env}"
-      empty_dir {
-        medium = "MEMORY"
-        size_limit = "256Mi"
+      name = local.cache_bucket_name
+      gcs {
+        bucket = local.cache_bucket_name
       }
     }
 
@@ -42,32 +124,50 @@ resource "google_cloud_run_v2_service" "default" {
         }
       }
 
-      env {
-        name = "APP_LOG_FORMAT"
-        value = "console"
+      # Use the cache bucket for WASM builds and Go modules.
+      volume_mounts {
+        name = local.cache_bucket_name
+        mount_path = local.cache_bucket_mount
       }
 
-      # Disable cache cleanup for stateless containers.
       env {
-        name = "APP_SKIP_MOD_CLEANUP"
-        value = "1"
+        name = "APP_BUILD_DIR"
+        value = "${local.cache_bucket_mount}/builds"
       }
 
       env {
-        name = "SENTRY_ENVIRONMENT"
-        value = var.app_env
+        name = "GOMODCACHE"
+        value = "${local.cache_bucket_mount}/mod"
       }
 
+      # Logging
       env {
-        name = "SENTRY_RELEASE"
-        value = "v${var.app_version}"
+        name = "APP_LOG_FORMAT"
+        value = "console"
       }
 
+      # Disable cache cleanup for stateless containers.
       env {
-        name = "SENTRY_DSN"
-        value = var.sentry_dsn
+        name = "APP_SKIP_MOD_CLEANUP"
+        value = "1"
       }
 
+      # Uncomment this if you're using Sentry.
+      # env {
+      #   name = "SENTRY_ENVIRONMENT"
+      #   value = var.app_env
+      # }
+
+      # env {
+      #   name = "SENTRY_RELEASE"
+      #   value = "v${var.app_version}"
+      # }
+
+      # env {
+      #   name = "SENTRY_DSN"
+      #   value = var.sentry_dsn
+      # }
+
       dynamic "env" {
         for_each = var.env_vars
         content {
@@ -76,17 +176,6 @@ resource "google_cloud_run_v2_service" "default" {
         }
       }
 
-      # Use WASM build cache directory.
-      env {
-        name = "APP_BUILD_DIR"
-        value = "/var/cache/wasm-builds"
-      }
-
-      volume_mounts {
-        name = "gpg-build-cache-${var.app_env}"
-        mount_path = "/var/cache/wasm-builds"
-      }
-
       startup_probe {
         http_get {
           path = "/api/version"