feat: add faas Cloud Run and Pub/Sub modules

terraform/faas_pubsub.tf

+variable "project_id" {
+  type        = string
+  description = "The Google Cloud project ID where resources will be provisioned."
+}
+
+module "pubsub" {
+  source                        = "./modules/pubsub"
+  topic_name                    = var.topic_name
+  dead_letter_topic_name        = var.dead_letter_topic_name
+  subscription_name             = var.subscription_name
+  dead_letter_subscription_name = var.dead_letter_subscription_name
+}
+
+module "faas_service" {
+  source          = "./modules/faas"
+  name            = var.name
+  container_image = var.container_image
+  location        = var.location
+  topic_id        = module.pubsub.main_topic_id
+  project_id      = var.project_id
+}

terraform/modules/faas/main.tf

+resource "google_project_service_identity" "pubsub_sa" {
+  provider = google-beta
+  project  = var.project_id
+  service  = "pubsub.googleapis.com"
+}
+
+resource "google_cloud_run_service" "faas" {
+  name     = var.name
+  location = var.location
+
+  template {
+    metadata {
+      annotations = {
+        "run.googleapis.com/service-account" = "serviceAccount:${google_project_service_identity.pubsub_sa.email}"
+      }
+    }
+
+    spec {
+      containers {
+        image = var.container_image
+      }
+    }
+  }
+
+  traffic {
+    percent         = 100
+    latest_revision = true
+  }
+}
+
+resource "google_eventarc_trigger" "trigger" {
+  name     = "${var.name}-trigger"
+  location = var.location
+
+  transport {
+    pubsub {
+      topic = var.topic_id
+    }
+  }
+
+  destination {
+    cloud_run_service {
+      service = google_cloud_run_service.faas.name
+    }
+  }
+
+  matching_criteria {
+    attribute = "type"
+    value     = "google.cloud.pubsub.topic.v1.messagePublished"
+  }
+
+  service_account = "serviceAccount:${google_project_service_identity.pubsub_sa.email}"
+}

terraform/modules/faas/outputs.tf

+output "service_url" {
+  value       = google_cloud_run_service.faas.status[0].url
+  description = "The URL on which the Cloud Run service is accessible."
+}

terraform/modules/faas/variables.tf

+variable "name" {
+  type        = string
+  description = "The name of the Cloud Run service."
+}
+
+variable "container_image" {
+  type        = string
+  description = "The container image to use for the Cloud Run service."
+}
+
+variable "location" {
+  type        = string
+  description = "The location where the service will be deployed."
+  default     = "europe-west2"
+}
+
+variable "topic_id" {
+  type        = string
+  description = "The ID of the Pub/Sub topic that triggers the function."
+}
+
+variable "project_id" {
+  type        = string
+  description = "The ID of the project where the resources will be deployed."
+}

terraform/modules/pubsub/main.tf

+resource "google_pubsub_topic" "main" {
+  name = var.topic_name
+}
+
+resource "google_pubsub_topic" "dead_letter" {
+  name = var.dead_letter_topic_name
+}
+
+resource "google_pubsub_subscription" "main" {
+  name  = var.subscription_name
+  topic = google_pubsub_topic.main.id
+
+  dead_letter_policy {
+    dead_letter_topic     = google_pubsub_topic.dead_letter.id
+    max_delivery_attempts = 5
+  }
+}
+
+resource "google_pubsub_subscription" "dead_letter" {
+  name  = var.dead_letter_subscription_name
+  topic = google_pubsub_topic.dead_letter.id
+}

terraform/modules/pubsub/outputs.tf

+output "main_topic_id" {
+  value       = google_pubsub_topic.main.id
+  description = "The ID of the main Pub/Sub topic."
+}
+
+output "dead_letter_topic_id" {
+  value       = google_pubsub_topic.dead_letter.id
+  description = "The ID of the dead letter Pub/Sub topic."
+}

terraform/modules/pubsub/variables.tf

+variable "topic_name" {
+  type        = string
+  description = "The name of the Pub/Sub topic."
+}
+
+variable "dead_letter_topic_name" {
+  type        = string
+  description = "The name of the dead letter topic."
+}
+
+variable "subscription_name" {
+  type        = string
+  description = "The name of the subscription."
+}
+
+variable "dead_letter_subscription_name" {
+  type        = string
+  description = "The name of the dead letter subscription."
+}