Add support for shared VPC in central project (closes #23)

README.md

@@ -137,6 +137,7 @@ module "iglu_lb" {
 | <a name="input_java_opts"></a> [java\_opts](#input\_java\_opts) | Custom JAVA Options | `string` | `"-XX:InitialRAMPercentage=75 -XX:MaxRAMPercentage=75"` | no |
 | <a name="input_labels"></a> [labels](#input\_labels) | The labels to append to this resource | `map(string)` | `{}` | no |
 | <a name="input_machine_type"></a> [machine\_type](#input\_machine\_type) | The machine type to use | `string` | `"e2-small"` | no |
+| <a name="input_network_project_id"></a> [network\_project\_id](#input\_network\_project\_id) | The project ID of the shared VPC in which the stack is being deployed | `string` | `""` | no |
 | <a name="input_patches_allowed"></a> [patches\_allowed](#input\_patches\_allowed) | Whether or not patches are allowed for published Iglu Schemas | `bool` | `true` | no |
 | <a name="input_ssh_block_project_keys"></a> [ssh\_block\_project\_keys](#input\_ssh\_block\_project\_keys) | Whether to block project wide SSH keys | `bool` | `true` | no |
 | <a name="input_ssh_ip_allowlist"></a> [ssh\_ip\_allowlist](#input\_ssh\_ip\_allowlist) | The list of CIDR ranges to allow SSH traffic from | `list(any)` | <pre>[<br>  "0.0.0.0/0"<br>]</pre> | no |

main.tf

@@ -58,7 +58,8 @@ resource "google_project_iam_member" "sa_cloud_sql_client" {
 # --- CE: Firewall rules
 
 resource "google_compute_firewall" "ingress_ssh" {
-  name = "${var.name}-ssh-in"
+  project = (var.network_project_id != "") ? var.network_project_id : var.project_id
+  name    = "${var.name}-ssh-in"
 
   network     = var.network
   target_tags = [var.name]
@@ -76,7 +77,8 @@ resource "google_compute_firewall" "ingress_ssh" {
 #
 # https://cloud.google.com/load-balancing/docs/health-check-concepts#ip-ranges
 resource "google_compute_firewall" "ingress" {
-  name = "${var.name}-traffic-in"
+  project = (var.network_project_id != "") ? var.network_project_id : var.project_id
+  name    = "${var.name}-traffic-in"
 
   network     = var.network
   target_tags = [var.name]
@@ -90,7 +92,8 @@ resource "google_compute_firewall" "ingress" {
 }
 
 resource "google_compute_firewall" "egress" {
-  name = "${var.name}-traffic-out"
+  project = (var.network_project_id != "") ? var.network_project_id : var.project_id
+  name    = "${var.name}-traffic-out"
 
   network     = var.network
   target_tags = [var.name]

variables.tf

@@ -25,6 +25,12 @@ variable "project_id" {
   type        = string
 }
 
+variable "network_project_id" {
+  description = "The project ID of the shared VPC in which the stack is being deployed"
+  type        = string
+  default     = ""
+}
+
 variable "region" {
   description = "The name of the region to deploy within"
   type        = string