fix(aws-ecs): handle long ARN formats for services

Due to a bug in Cloudformation, Fn::GetAtt for service name on an ECS
service was returning the cluster name instead of the service name. This
was causing the ResourceId on AWS::ApplicationAutoScaling::ScalableTarget to be set incorrectly.

Fixes aws#1849.

packages/@aws-cdk/aws-ecs/lib/base/base-service.ts

@@ -62,6 +62,21 @@ export interface BaseServiceProps {
  * Options for enabling AWS Cloud Map service discovery for the service
  */
  readonly serviceDiscoveryOptions?: ServiceDiscoveryOptions;
+
+ /**
+ * Whether the new long ARN format has been enabled on ECS services.
+ * NOTE: This assumes customer has opted into the new format for the IAM role used for the service, and is a
+ * workaround for a current bug in Cloudformation in which the service name is not correctly returned when long ARN is
+ * enabled.
+ *
+ * Old ARN format: arn:aws:ecs:region:aws_account_id:service/service-name
+ * New ARN format: arn:aws:ecs:region:aws_account_id:service/cluster-name/service-name
+ *
+ * See: https://docs.aws.amazon.com/AmazonECS/latest/userguide/ecs-resource-ids.html
+ *
+ * @default false
+ */
+ readonly longArnEnabled?: boolean;
 }
 
 /**
@@ -95,6 +110,11 @@ export abstract class BaseService extends cdk.Construct
  */
  public readonly taskDefinition: TaskDefinition;
 
+ /**
+ * Whether the new long ARN format has been enabled on ECS services.
+ */
+ public readonly longArnEnabled: boolean;
+
  protected cloudmapService?: cloudmap.Service;
  protected cluster: ICluster;
  protected loadBalancers = new Array<CfnService.LoadBalancerProperty>();
@@ -128,15 +148,22 @@ export abstract class BaseService extends cdk.Construct
  serviceRegistries: new cdk.Token(() => this.serviceRegistries),
  ...additionalProps
  });
+
+ this.longArnEnabled = props.longArnEnabled !== undefined ? props.longArnEnabled : false;
  this.serviceArn = this.resource.serviceArn;
- this.serviceName = this.resource.serviceName;
+
+ // This is a workaround for CFN bug that returns the cluster name instead of the service name when long ARN formats
+ // are enabled for the principal in a given region.
+ this.serviceName = this.longArnEnabled
+ ? cdk.Fn.select(2, cdk.Fn.split('/', this.serviceArn))
+ : this.resource.serviceName;
+
  this.clusterName = clusterName;
  this.cluster = props.cluster;
 
  if (props.serviceDiscoveryOptions) {
  this.enableServiceDiscovery(props.serviceDiscoveryOptions);
  }
-
  }
 
  /**
@@ -177,7 +204,7 @@ export abstract class BaseService extends cdk.Construct
 
  return this.scalableTaskCount = new ScalableTaskCount(this, 'TaskCount', {
  serviceNamespace: appscaling.ServiceNamespace.Ecs,
- resourceId: `service/${this.clusterName}/${this.resource.serviceName}`,
+ resourceId: `service/${this.clusterName}/${this.serviceName}`,
  dimension: 'ecs:service:DesiredCount',
  role: this.makeAutoScalingRole(),
  ...props

packages/@aws-cdk/aws-ecs/test/fargate/integ.lb-awsvpc-nw.expected.json

@@ -522,9 +522,16 @@
  },
  "/",
  {
- "Fn::GetAtt": [
- "ServiceD69D759B",
- "Name"
+ "Fn::Select": [
+ 2,
+ {
+ "Fn::Split": [
+ "/",
+ {
+ "Ref": "ServiceD69D759B"
+ }
+ ]
+ }
  ]
  }
  ]
@@ -682,4 +689,4 @@
  }
  }
  }
-}
+}

packages/@aws-cdk/aws-ecs/test/fargate/integ.lb-awsvpc-nw.ts

@@ -27,6 +27,7 @@ container.addPortMappings({
 const service = new ecs.FargateService(stack, "Service", {
  cluster,
  taskDefinition,
+ longArnEnabled: true
 });
 
 const scaling = service.autoScaleTaskCount({ maxCapacity: 10 });

packages/@aws-cdk/aws-ecs/test/fargate/test.fargate-service.ts

@@ -216,7 +216,25 @@ export = {
  // THEN
  expect(stack).to(haveResource('AWS::ApplicationAutoScaling::ScalableTarget', {
  MaxCapacity: 10,
- MinCapacity: 1
+ MinCapacity: 1,
+ ResourceId: {
+ "Fn::Join": [
+ "",
+ [
+ "service/",
+ {
+ Ref: "EcsCluster97242B84"
+ },
+ "/",
+ {
+ "Fn::GetAtt": [
+ "ServiceD69D759B",
+ "Name"
+ ]
+ }
+ ]
+ ]
+ },
  }));
 
  expect(stack).to(haveResource('AWS::ApplicationAutoScaling::ScalingPolicy', {
@@ -236,6 +254,71 @@ export = {
  }
  }));
 
+ test.done();
+ },
+
+ 'allows auto scaling by ALB with new service arn format'(test: Test) {
+ // GIVEN
+ const stack = new cdk.Stack();
+ const vpc = new ec2.VpcNetwork(stack, 'MyVpc', {});
+ const cluster = new ecs.Cluster(stack, 'EcsCluster', { vpc });
+ const taskDefinition = new ecs.FargateTaskDefinition(stack, 'FargateTaskDef');
+ const container = taskDefinition.addContainer('MainContainer', {
+ image: ContainerImage.fromRegistry('hello'),
+ });
+ container.addPortMappings({ containerPort: 8000 });
+
+ const service = new ecs.FargateService(stack, 'Service', {
+ cluster,
+ taskDefinition,
+ longArnEnabled: true
+ });
+
+ const lb = new elbv2.ApplicationLoadBalancer(stack, "lb", { vpc });
+ const listener = lb.addListener("listener", { port: 80 });
+ const targetGroup = listener.addTargets("target", {
+ port: 80,
+ targets: [service]
+ });
+
+ // WHEN
+ const capacity = service.autoScaleTaskCount({ maxCapacity: 10, minCapacity: 1 });
+ capacity.scaleOnRequestCount("ScaleOnRequests", {
+ requestsPerTarget: 1000,
+ targetGroup
+ });
+
+ // THEN
+ expect(stack).to(haveResource('AWS::ApplicationAutoScaling::ScalableTarget', {
+ MaxCapacity: 10,
+ MinCapacity: 1,
+ ResourceId: {
+ "Fn::Join": [
+ "",
+ [
+ "service/",
+ {
+ Ref: "EcsCluster97242B84"
+ },
+ "/",
+ {
+ "Fn::Select": [
+ 2,
+ {
+ "Fn::Split": [
+ "/",
+ {
+ Ref: "ServiceD69D759B"
+ }
+ ]
+ }
+ ]
+ }
+ ]
+ ]
+ },
+ }));
+
  test.done();
  }
  },
@@ -384,5 +467,6 @@ export = {
 
  test.done();
  },
+
  }
 };