fix: Pin network module for terraform 0.12 (#333)

Author: deas

4-projects/business_unit_1/development/example_peering_project.tf

@@ -64,8 +64,8 @@ module "peering_network" {
 }
 
 module "peering" {
-  source = "terraform-google-modules/network/google//modules/network-peering"
-
+  source        = "terraform-google-modules/network/google//modules/network-peering"
+  version       = "~> 2.0"
   prefix        = "bu1-d"
   local_network = module.peering_network.network_self_link
   peer_network  = data.google_compute_network.shared_vpc.self_link

4-projects/business_unit_1/non-production/example_peering_project.tf

@@ -64,8 +64,8 @@ module "peering_network" {
 }
 
 module "peering" {
-  source = "terraform-google-modules/network/google//modules/network-peering"
-
+  source        = "terraform-google-modules/network/google//modules/network-peering"
+  version       = "~> 2.0"
   prefix        = "bu1-n"
   local_network = module.peering_network.network_self_link
   peer_network  = data.google_compute_network.shared_vpc.self_link

4-projects/business_unit_1/production/example_peering_project.tf

@@ -65,6 +65,7 @@ module "peering_network" {
 
 module "peering" {
   source        = "terraform-google-modules/network/google//modules/network-peering"
+  version       = "~> 2.0"
   prefix        = "bu1-p"
   local_network = module.peering_network.network_self_link
   peer_network  = data.google_compute_network.shared_vpc.self_link

4-projects/business_unit_2/development/example_peering_project.tf

@@ -64,8 +64,8 @@ module "peering_network" {
 }
 
 module "peering" {
-  source = "terraform-google-modules/network/google//modules/network-peering"
-
+  source        = "terraform-google-modules/network/google//modules/network-peering"
+  version       = "~> 2.0"
   prefix        = "bu2-d"
   local_network = module.peering_network.network_self_link
   peer_network  = data.google_compute_network.shared_vpc.self_link

4-projects/business_unit_2/non-production/example_peering_project.tf

@@ -65,6 +65,7 @@ module "peering_network" {
 
 module "peering" {
   source        = "terraform-google-modules/network/google//modules/network-peering"
+  version       = "~> 2.0"
   prefix        = "bu2-n"
   local_network = module.peering_network.network_self_link
   peer_network  = data.google_compute_network.shared_vpc.self_link

4-projects/business_unit_2/production/example_peering_project.tf

@@ -65,6 +65,7 @@ module "peering_network" {
 
 module "peering" {
   source        = "terraform-google-modules/network/google//modules/network-peering"
+  version       = "~> 2.0"
   prefix        = "bu2-p"
   local_network = module.peering_network.network_self_link
   peer_network  = data.google_compute_network.shared_vpc.self_link