.review_apps: enable Traefik to handle a new ECS task coming online d…

…uring a deployment

Previously we had to limit the number of deployed tasks for a review app to
exactly one, because Traefik would complain about duplicate service names for
the duration of the cross over.

To avoid that, we add a timestamp to the service name, so they're always
unique.

.review_apps/ecs_service.tf

@@ -5,15 +5,19 @@ resource "aws_ecs_service" "app" {
   task_definition = aws_ecs_task_definition.task.arn
 
   desired_count                      = 1
-  deployment_maximum_percent         = "100"
-  deployment_minimum_healthy_percent = "0"
+  deployment_maximum_percent         = "200"
+  deployment_minimum_healthy_percent = "100"
+  force_new_deployment               = true
+
 
   launch_type      = "FARGATE"
   platform_version = "1.4.0"
 
   network_configuration {
     subnets          = data.terraform_remote_state.review.outputs.private_subnet_ids
-    security_groups = [data.terraform_remote_state.review.outputs.review_apps_security_group_id]
+    security_groups  = [data.terraform_remote_state.review.outputs.review_apps_security_group_id]
     assign_public_ip = false
   }
+
+  depends_on = [aws_ecs_task_definition.task]
 }

.review_apps/ecs_task_definition.tf

@@ -1,6 +1,8 @@
 locals {
   logs_stream_prefix = "${data.terraform_remote_state.review.outputs.review_apps_log_group_name}/pr-${var.pull_request_number}"
 
+  service_timestamp = provider::time::rfc3339_parse(plantimestamp())
+
   forms_admin_startup_commands = [
     "bundle config unset --local without",
     "bundle install",
@@ -63,6 +65,7 @@ resource "aws_ecs_task_definition" "task" {
 
       dockerLabels = {
         "traefik.http.routers.forms-admin-pr-${var.pull_request_number}.rule" : "Host(`pr-${var.pull_request_number}.review.forms.service.gov.uk`)",
+        "traefik.http.routers.forms-admin-pr-${var.pull_request_number}.service" : "forms-admin-pr-${var.pull_request_number}",
         "traefik.http.services.forms-admin-pr-${var.pull_request_number}.loadbalancer.server.port" : "3000",
         "traefik.http.services.forms-admin-pr-${var.pull_request_number}.loadbalancer.healthcheck.path" : "/up",
         "traefik.enable" : "true"

.review_apps/site.tf

@@ -6,6 +6,11 @@ terraform {
       source  = "hashicorp/aws"
       version = "~> 5.72.1"
     }
+
+    time = {
+      source  = "hashicorp/time"
+      version = "0.11.1"
+    }
   }
 
   backend "s3" {