fix(elasticloadbalancingv2): target group health check does not validate interval versus timeout (#16107)

fix: Add validation to target group health check creation. Fixes issue #3703.

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: mprencipe

packages/@aws-cdk/aws-elasticloadbalancingv2/lib/shared/base-target-group.ts

@@ -297,6 +297,11 @@ export abstract class TargetGroupBase extends CoreConstruct implements ITargetGr
    * Set/replace the target group's health check
    */
   public configureHealthCheck(healthCheck: HealthCheck) {
+    if (healthCheck.interval && healthCheck.timeout) {
+      if (healthCheck.interval.toMilliseconds() <= healthCheck.timeout.toMilliseconds()) {
+        throw new Error(`Healthcheck interval ${healthCheck.interval.toHumanString()} must be greater than the timeout ${healthCheck.timeout.toHumanString()}`);
+      }
+    }
     this.healthCheck = healthCheck;
   }
 

packages/@aws-cdk/aws-elasticloadbalancingv2/test/alb/listener.test.ts

@@ -437,17 +437,17 @@ describe('tests', () => {
     });
     group.configureHealthCheck({
       unhealthyThresholdCount: 3,
-      timeout: cdk.Duration.hours(1),
-      interval: cdk.Duration.seconds(30),
+      timeout: cdk.Duration.seconds(30),
+      interval: cdk.Duration.seconds(60),
       path: '/test',
     });
 
     // THEN
     expect(stack).toHaveResource('AWS::ElasticLoadBalancingV2::TargetGroup', {
       UnhealthyThresholdCount: 3,
-      HealthCheckIntervalSeconds: 30,
+      HealthCheckIntervalSeconds: 60,
       HealthCheckPath: '/test',
-      HealthCheckTimeoutSeconds: 3600,
+      HealthCheckTimeoutSeconds: 30,
     });
   });
 
@@ -466,8 +466,8 @@ describe('tests', () => {
 
     group.configureHealthCheck({
       unhealthyThresholdCount: 3,
-      timeout: cdk.Duration.hours(1),
-      interval: cdk.Duration.seconds(30),
+      timeout: cdk.Duration.seconds(30),
+      interval: cdk.Duration.seconds(60),
       path: '/test',
       protocol: elbv2.Protocol.TCP,
     });

packages/@aws-cdk/aws-elasticloadbalancingv2/test/alb/target-group.test.ts

@@ -281,4 +281,45 @@ describe('tests', () => {
       }).toThrow(/Slow start duration value must be between 30 and 900 seconds./);
     });
   });
+
+  test('Interval equal to timeout', () => {
+    // GIVEN
+    const app = new cdk.App();
+    const stack = new cdk.Stack(app, 'Stack');
+    const vpc = new ec2.Vpc(stack, 'VPC', {});
+
+    // WHEN
+    const tg = new elbv2.ApplicationTargetGroup(stack, 'TargetGroup', {
+      vpc,
+    });
+
+    // THEN
+    expect(() => {
+      tg.configureHealthCheck({
+        interval: cdk.Duration.seconds(60),
+        timeout: cdk.Duration.seconds(60),
+      });
+    }).toThrow(/Healthcheck interval 1 minute must be greater than the timeout 1 minute/);
+  });
+
+  test('Interval smaller than timeout', () => {
+    // GIVEN
+    const app = new cdk.App();
+    const stack = new cdk.Stack(app, 'Stack');
+    const vpc = new ec2.Vpc(stack, 'VPC', {});
+
+    // WHEN
+    const tg = new elbv2.ApplicationTargetGroup(stack, 'TargetGroup', {
+      vpc,
+    });
+
+    // THEN
+    expect(() => {
+      tg.configureHealthCheck({
+        interval: cdk.Duration.seconds(60),
+        timeout: cdk.Duration.seconds(120),
+      });
+    }).toThrow(/Healthcheck interval 1 minute must be greater than the timeout 2 minutes/);
+  });
+
 });