Mark externally managed terraform resources to make infrastructure terraform appliable throughout its lifetime (#442)

* Mark externally managed terraform resources to make infrastructure terraform appliable throughout its lifetime
* Use correct field for nat gateway

Signed-off-by: Paul Meyer <49727155+katexochen@users.noreply.github.com>
Co-authored-by: Paul Meyer <49727155+katexochen@users.noreply.github.com>

cli/internal/terraform/terraform/aws/modules/instance_group/main.tf

@@ -39,10 +39,14 @@ resource "aws_launch_template" "launch_template" {
 
   lifecycle {
     create_before_destroy = true
+    ignore_changes = [
+      default_version, # required. update procedure creates new versions of the launch template
+      image_id,        # required. update procedure modifies the image id externally
+    ]
   }
 }
 
-resource "aws_autoscaling_group" "control_plane_autoscaling_group" {
+resource "aws_autoscaling_group" "autoscaling_group" {
   name = local.name
   launch_template {
     id = aws_launch_template.launch_template.id
@@ -53,10 +57,6 @@ resource "aws_autoscaling_group" "control_plane_autoscaling_group" {
   vpc_zone_identifier = [var.subnetwork]
   target_group_arns   = var.target_group_arns
 
-  lifecycle {
-    create_before_destroy = true
-  }
-
   tag {
     key                 = "Name"
     value               = local.name
@@ -78,4 +78,14 @@ resource "aws_autoscaling_group" "control_plane_autoscaling_group" {
     value               = "Constellation-${var.uid}"
     propagate_at_launch = true
   }
+
+  lifecycle {
+    create_before_destroy = true
+    ignore_changes = [
+      launch_template.0.version, # required. update procedure creates new versions of the launch template
+      min_size,                  # required. autoscaling modifies the instance count externally
+      max_size,                  # required. autoscaling modifies the instance count externally
+      desired_capacity,          # required. autoscaling modifies the instance count externally
+    ]
+  }
 }

cli/internal/terraform/terraform/aws/modules/public_private_subnet/main.tf

@@ -43,7 +43,7 @@ resource "aws_route_table" "private_nat" {
 
   route {
     cidr_block     = "0.0.0.0/0"
-    gateway_id = aws_nat_gateway.gw.id
+    nat_gateway_id = aws_nat_gateway.gw.id
   }
 }
 

cli/internal/terraform/terraform/azure/modules/scale_set/main.tf

@@ -78,4 +78,11 @@ resource "azurerm_linux_virtual_machine_scale_set" "scale_set" {
       load_balancer_backend_address_pool_ids = var.backend_address_pool_ids
     }
   }
+
+  lifecycle {
+    ignore_changes = [
+      instances,       # required. autoscaling modifies the instance count externally
+      source_image_id, # required. update procedure modifies the image id externally
+    ]
+  }
 }

cli/internal/terraform/terraform/gcp/modules/instance_group/main.tf

@@ -94,4 +94,11 @@ resource "google_compute_instance_group_manager" "instance_group_manager" {
       port = named_port.value.port
     }
   }
+
+  lifecycle {
+    ignore_changes = [
+      target_size, # required. autoscaling modifies the instance count externally
+      version,     # required. update procedure modifies the instance template externally
+    ]
+  }
 }