feat(route53): add classic elb target support (aws#3380)

* feat(route53-targets): add classic elb target support

* fix(route53-targets): doc example

Co-Authored-By: Jonathan Goldwasser <jogold@users.noreply.github.com>

* chore(route53): fix export ordering

packages/@aws-cdk/aws-route53-targets/README.md

@@ -33,5 +33,13 @@ This library contains Route53 Alias Record targets for:
     // or - route53.RecordTarget.fromAlias(new alias.ApiGatewayDomainName(domainName)),
   });
   ```
+* Classic load balancers
+  ```ts
+  new route53.ARecord(this, 'AliasRecord', {
+    zone,
+    target: route53.RecordTarget.fromAlias(new alias.ClassicLoadBalancerTarget(elb)),
+    // or - route53.RecordTarget.fromAlias(new alias.ApiGatewayDomainName(domainName)),
+  });
+  ```
 
 See the documentation of `@aws-cdk/aws-route53` for more information.

packages/@aws-cdk/aws-route53-targets/lib/classic-load-balancer-target.ts

@@ -0,0 +1,17 @@
+import elb = require('@aws-cdk/aws-elasticloadbalancing');
+import route53 = require('@aws-cdk/aws-route53');
+
+/**
+ * Use a classic ELB as an alias record target
+ */
+export class ClassicLoadBalancerTarget implements route53.IAliasRecordTarget {
+  constructor(private readonly loadBalancer: elb.LoadBalancer) {
+  }
+
+  public bind(_record: route53.IRecordSet): route53.AliasRecordTargetConfig {
+    return {
+      hostedZoneId: this.loadBalancer.loadBalancerCanonicalHostedZoneNameId,
+      dnsName: this.loadBalancer.loadBalancerDnsName
+    };
+  }
+}

packages/@aws-cdk/aws-route53-targets/lib/index.ts

@@ -1,3 +1,4 @@
 export * from './api-gateway-domain-name';
+export * from './classic-load-balancer-target';
 export * from './cloudfront-target';
 export * from './load-balancer-target';

packages/@aws-cdk/aws-route53-targets/package.json

@@ -85,6 +85,7 @@
     "@aws-cdk/aws-apigateway": "^1.3.0",
     "@aws-cdk/aws-cloudfront": "^1.3.0",
     "@aws-cdk/aws-elasticloadbalancingv2": "^1.3.0",
+    "@aws-cdk/aws-elasticloadbalancing": "^1.3.0",
     "@aws-cdk/aws-iam": "^1.3.0",
     "@aws-cdk/aws-route53": "^1.3.0",
     "@aws-cdk/core": "^1.3.0"
@@ -94,6 +95,7 @@
     "@aws-cdk/aws-apigateway": "^1.3.0",
     "@aws-cdk/aws-cloudfront": "^1.3.0",
     "@aws-cdk/aws-elasticloadbalancingv2": "^1.3.0",
+    "@aws-cdk/aws-elasticloadbalancing": "^1.3.0",
     "@aws-cdk/aws-iam": "^1.3.0",
     "@aws-cdk/aws-route53": "^1.3.0",
     "@aws-cdk/core": "^1.3.0"

packages/@aws-cdk/aws-route53-targets/test/classic-load-balancer-target.test.ts

@@ -0,0 +1,35 @@
+import '@aws-cdk/assert/jest';
+import ec2 = require('@aws-cdk/aws-ec2');
+import elb = require('@aws-cdk/aws-elasticloadbalancing');
+import route53 = require('@aws-cdk/aws-route53');
+import { Stack } from '@aws-cdk/core';
+import targets = require('../lib');
+
+test('use classic ELB as record target', () => {
+  // GIVEN
+  const stack = new Stack();
+  const vpc = new ec2.Vpc(stack, 'VPC', {
+    maxAzs: 2
+  });
+  const lb = new elb.LoadBalancer(stack, 'LB', {
+    vpc,
+    internetFacing: true
+  });
+
+  const zone = new route53.PublicHostedZone(stack, 'HostedZone', { zoneName: 'test.public' });
+
+  // WHEN
+  new route53.ARecord(zone, 'Alias', {
+    zone,
+    recordName: '_foo',
+    target: route53.AddressRecordTarget.fromAlias(new targets.ClassicLoadBalancerTarget(lb))
+  });
+
+  // THEN
+  expect(stack).toHaveResource('AWS::Route53::RecordSet', {
+    AliasTarget: {
+      DNSName: { "Fn::GetAtt": [ "LB8A12904C", "DNSName" ] },
+      HostedZoneId: { "Fn::GetAtt": [ "LB8A12904C", "CanonicalHostedZoneNameID" ] }
+    },
+  });
+});