From 12b6d89503fafdb645c5721d3b07d301fcd72521 Mon Sep 17 00:00:00 2001
From: David Horsman <56004724+horsmand@users.noreply.github.com>
Date: Mon, 8 Feb 2021 17:52:26 -0600
Subject: [PATCH] feat(core): add vpcSubnets prop to HealthMonitor (#310)

Fixes #305
---
 .../aws-rfdk/lib/core/lib/health-monitor.ts   |  8 +++++
 .../lib/core/lib/load-balancer-manager.ts     |  1 +
 .../lib/core/test/health-monitor.test.ts      | 34 +++++++++++++++++++
 3 files changed, 43 insertions(+)

diff --git a/packages/aws-rfdk/lib/core/lib/health-monitor.ts b/packages/aws-rfdk/lib/core/lib/health-monitor.ts
index 4e89d5476..96c2a9ae2 100644
--- a/packages/aws-rfdk/lib/core/lib/health-monitor.ts
+++ b/packages/aws-rfdk/lib/core/lib/health-monitor.ts
@@ -16,6 +16,7 @@ import {
   IConnectable,
   IVpc,
   Port,
+  SubnetSelection,
 } from '@aws-cdk/aws-ec2';
 import {
   ApplicationLoadBalancer,
@@ -202,6 +203,13 @@ export interface HealthMonitorProps {
    * @see https://docs.aws.amazon.com/elasticloadbalancing/latest/application/application-load-balancers.html#deletion-protection
    */
   readonly deletionProtection?: boolean;
+
+  /**
+   * Any load balancers that get created by calls to registerFleet() will be created in these subnets.
+   *
+   * @default: The VPC default strategy
+   */
+  readonly vpcSubnets?: SubnetSelection;
 }
 
 /**
diff --git a/packages/aws-rfdk/lib/core/lib/load-balancer-manager.ts b/packages/aws-rfdk/lib/core/lib/load-balancer-manager.ts
index 16e105836..22c577639 100644
--- a/packages/aws-rfdk/lib/core/lib/load-balancer-manager.ts
+++ b/packages/aws-rfdk/lib/core/lib/load-balancer-manager.ts
@@ -198,6 +198,7 @@ export class LoadBalancerFactory {
     const loadBalancer = new ApplicationLoadBalancer(scope, `ALB_${loadBalancerindex}`, {
       vpc: this.vpc,
       internetFacing: false,
+      vpcSubnets: healthMonitorProps.vpcSubnets,
       deletionProtection: healthMonitorProps.deletionProtection ?? true,
     });
     // Enabling dropping of invalid HTTP header fields on the load balancer to prevent http smuggling attacks.
diff --git a/packages/aws-rfdk/lib/core/test/health-monitor.test.ts b/packages/aws-rfdk/lib/core/test/health-monitor.test.ts
index 113c8919c..eaef54476 100644
--- a/packages/aws-rfdk/lib/core/test/health-monitor.test.ts
+++ b/packages/aws-rfdk/lib/core/test/health-monitor.test.ts
@@ -13,6 +13,8 @@ import {
   haveResourceLike,
   not,
   ABSENT,
+  notMatching,
+  stringLike,
 } from '@aws-cdk/assert';
 import {
   AutoScalingGroup,
@@ -30,6 +32,7 @@ import {
   InstanceSize,
   InstanceType,
   IVpc,
+  SubnetType,
   Vpc,
 } from '@aws-cdk/aws-ec2';
 import {IApplicationLoadBalancerTarget} from '@aws-cdk/aws-elasticloadbalancingv2';
@@ -532,6 +535,37 @@ describe('HealthMonitor', () => {
     }));
   });
 
+  test('specifying a subnet', () => {
+    // WHEN
+    healthMonitor = new HealthMonitor(hmStack, 'healthMonitor2', {
+      vpc,
+      vpcSubnets: {
+        subnetType: SubnetType.PUBLIC,
+      },
+    });
+
+    const fleet = new TestMonitorableFleet(wfStack, 'workerFleet', {
+      vpc,
+    });
+    healthMonitor.registerFleet(fleet, {});
+
+    // THEN
+    // Make sure it has the public subnets
+    expectCDK(hmStack).to(haveResourceLike('AWS::ElasticLoadBalancingV2::LoadBalancer', {
+      Subnets: [
+        {'Fn::ImportValue': stringLike('*PublicSubnet*')},
+        {'Fn::ImportValue': stringLike('*PublicSubnet*')},
+      ],
+    }));
+    // Make sure the private subnets aren't present
+    expectCDK(hmStack).to(haveResourceLike('AWS::ElasticLoadBalancingV2::LoadBalancer', {
+      Subnets: [
+        {'Fn::ImportValue': notMatching(stringLike('*PrivateSubnet*'))},
+        {'Fn::ImportValue': notMatching(stringLike('*PrivateSubnet*'))},
+      ],
+    }));
+  });
+
   describe('tagging', () => {
     testConstructTags({
       constructName: 'HealthMonitor',