feat: Allow creating subscriptions without creating topic (#72)

BREAKING CHANGE: The `create_subscriptions` variable is now used to control whether subscriptions should be created. Set `create_subscriptions = false` *and* `create_topic = false` if you don't want the module to do anything.

README.md

@@ -57,6 +57,7 @@ module "pubsub" {
 
 | Name | Description | Type | Default | Required |
 |------|-------------|------|---------|:--------:|
+| create\_subscriptions | Specify true if you want to create subscriptions | `bool` | `true` | no |
 | create\_topic | Specify true if you want to create a topic | `bool` | `true` | no |
 | grant\_token\_creator | Specify true if you want to add token creator role to the default Pub/Sub SA | `bool` | `true` | no |
 | message\_storage\_policy | A map of storage policies. Default - inherit from organization's Resource Location Restriction policy. | `map(any)` | `{}` | no |

examples/simple/main.tf

@@ -25,6 +25,7 @@ module "pubsub" {
   topic        = var.topic_name
   topic_labels = var.topic_labels
 
+
   pull_subscriptions = [
     {
       name                 = "pull"

examples/subscriptions_only/README.md

@@ -0,0 +1,36 @@
+# Simple Example - Creates Subscriptions Only
+
+This example illustrates how to use the `pubsub` module  to create only subscriptions.
+
+<!-- BEGINNING OF PRE-COMMIT-TERRAFORM DOCS HOOK -->
+## Inputs
+
+| Name | Description | Type | Default | Required |
+|------|-------------|------|---------|:--------:|
+| project\_id | The project ID to manage the Pub/Sub resources | `string` | n/a | yes |
+| topic\_project | The project ID of the topic | `string` | n/a | yes |
+
+## Outputs
+
+| Name | Description |
+|------|-------------|
+| project\_id | The project ID |
+| topic\_labels | The labels of the Pub/Sub topic created |
+| topic\_name | The name of the Pub/Sub topic created |
+
+<!-- END OF PRE-COMMIT-TERRAFORM DOCS HOOK -->
+
+## Requirements
+
+The following sections describe the requirements which must be met in
+order to invoke this example. The requirements of the
+[root module][root-module-requirements] must be met.
+
+## Usage
+
+To provision this example, populate `terraform.tfvars` with the [required variables](#inputs) and run the following commands within
+this directory:
+- `terraform init` to get the plugins
+- `terraform plan` to see the infrastructure plan
+- `terraform apply` to apply the infrastructure build
+- `terraform destroy` to destroy the built infrastructure

examples/subscriptions_only/main.tf

@@ -0,0 +1,52 @@
+/**
+ * Copyright 2018 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+provider "google" {
+  version = "~> 3.51"
+  region  = "us-central1"
+}
+
+resource "google_pubsub_topic" "example" {
+  name    = "terraform-test-topic"
+  project = var.topic_project
+
+}
+module "pubsub" {
+  source               = "../../"
+  project_id           = var.project_id
+  create_topic         = false
+  create_subscriptions = true
+  topic                = google_pubsub_topic.example.id
+
+
+  pull_subscriptions = [
+    {
+      name                 = "pull"
+      ack_deadline_seconds = 10
+    },
+  ]
+
+  push_subscriptions = [
+    {
+      name                 = "push"
+      push_endpoint        = "https://${var.project_id}.appspot.com/"
+      x-goog-version       = "v1beta1"
+      ack_deadline_seconds = 20
+      expiration_policy    = "1209600s" // two weeks
+    },
+  ]
+
+}

examples/subscriptions_only/outputs.tf

@@ -0,0 +1,30 @@
+/**
+ * Copyright 2018 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+output "project_id" {
+  value       = var.project_id
+  description = "The project ID"
+}
+
+output "topic_name" {
+  value       = module.pubsub.topic
+  description = "The name of the Pub/Sub topic created"
+}
+
+output "topic_labels" {
+  value       = module.pubsub.topic_labels
+  description = "The labels of the Pub/Sub topic created"
+}

examples/subscriptions_only/variables.tf

@@ -0,0 +1,25 @@
+/**
+ * Copyright 2018 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+variable "project_id" {
+  type        = string
+  description = "The project ID to manage the Pub/Sub resources"
+}
+
+variable "topic_project" {
+  type        = string
+  description = "The project ID of the topic"
+}

main.tf

@@ -58,7 +58,7 @@ resource "google_pubsub_topic_iam_member" "pull_topic_binding" {
 }
 
 resource "google_pubsub_subscription_iam_member" "pull_subscription_binding" {
-  for_each = var.create_topic ? { for i in var.pull_subscriptions : i.name => i } : {}
+  for_each = var.create_subscriptions ? { for i in var.pull_subscriptions : i.name => i } : {}
 
   project      = var.project_id
   subscription = each.value.name
@@ -70,7 +70,7 @@ resource "google_pubsub_subscription_iam_member" "pull_subscription_binding" {
 }
 
 resource "google_pubsub_subscription_iam_member" "push_subscription_binding" {
-  for_each = var.create_topic ? { for i in var.push_subscriptions : i.name => i } : {}
+  for_each = var.create_subscriptions ? { for i in var.push_subscriptions : i.name => i } : {}
 
   project      = var.project_id
   subscription = each.value.name
@@ -97,10 +97,10 @@ resource "google_pubsub_topic" "topic" {
 }
 
 resource "google_pubsub_subscription" "push_subscriptions" {
-  for_each = var.create_topic ? { for i in var.push_subscriptions : i.name => i } : {}
+  for_each = var.create_subscriptions ? { for i in var.push_subscriptions : i.name => i } : {}
 
   name    = each.value.name
-  topic   = google_pubsub_topic.topic.0.name
+  topic   = var.create_topic ? google_pubsub_topic.topic.0.name : var.topic
   project = var.project_id
   labels  = var.subscription_labels
   ack_deadline_seconds = lookup(
@@ -175,10 +175,10 @@ resource "google_pubsub_subscription" "push_subscriptions" {
 }
 
 resource "google_pubsub_subscription" "pull_subscriptions" {
-  for_each = var.create_topic ? { for i in var.pull_subscriptions : i.name => i } : {}
+  for_each = var.create_subscriptions ? { for i in var.pull_subscriptions : i.name => i } : {}
 
   name    = each.value.name
-  topic   = google_pubsub_topic.topic.0.name
+  topic   = var.create_topic ? google_pubsub_topic.topic.0.name : var.topic
   project = var.project_id
   labels  = var.subscription_labels
   ack_deadline_seconds = lookup(
@@ -236,7 +236,7 @@ resource "google_pubsub_subscription" "pull_subscriptions" {
 }
 
 resource "google_pubsub_subscription_iam_member" "pull_subscription_sa_binding_subscriber" {
-  for_each = var.create_topic ? { for i in var.pull_subscriptions : i.name => i if lookup(i, "service_account", null) != null } : {}
+  for_each = var.create_subscriptions ? { for i in var.pull_subscriptions : i.name => i if lookup(i, "service_account", null) != null } : {}
 
   project      = var.project_id
   subscription = each.value.name
@@ -248,7 +248,7 @@ resource "google_pubsub_subscription_iam_member" "pull_subscription_sa_binding_s
 }
 
 resource "google_pubsub_subscription_iam_member" "pull_subscription_sa_binding_viewer" {
-  for_each = var.create_topic ? { for i in var.pull_subscriptions : i.name => i if lookup(i, "service_account", null) != null } : {}
+  for_each = var.create_subscriptions ? { for i in var.pull_subscriptions : i.name => i if lookup(i, "service_account", null) != null } : {}
 
   project      = var.project_id
   subscription = each.value.name

variables.tf

@@ -30,6 +30,11 @@ variable "create_topic" {
   default     = true
 }
 
+variable "create_subscriptions" {
+  type        = bool
+  description = "Specify true if you want to create subscriptions"
+  default     = true
+}
 variable "topic_labels" {
   type        = map(string)
   description = "A map of labels to assign to the Pub/Sub topic"