feat(elasticloadbalancingv2): add removeSuffix param for ExternalApplicationListener.addAction()

packages/aws-cdk-lib/aws-elasticloadbalancingv2/README.md

@@ -765,3 +765,16 @@ const targetGroup = elbv2.ApplicationTargetGroup.fromTargetGroupAttributes(this,
 
 const targetGroupMetrics: elbv2.IApplicationTargetGroupMetrics = targetGroup.metrics; // throws an Error()
 ```
+
+## logicalIds on ExternalApplicationListener.addTargetGroups() and .addAction()
+
+By default, the `addTargetGroups()` method does not follow the standard behavior
+of adding a `Rule` suffix to the logicalId of the `ListenerRule` it creates.
+If you are deploying new `ListenerRule`s using `addTargetGroups()` the recommendation
+is to set the `removeRuleSuffixFromLogicalId: false` property.
+If you have `ListenerRule`s deployed using the legacy behavior of `addTargetGroups()`,
+which you need to switch over to being managed by the `addAction()` method,
+then you will need to enable the `removeRuleSuffixFromLogicalId: true` property in the `addAction()` method.
+
+`ListenerRule`s have a unique `priority` for a given `Listener`.
+Because the `priority` must be unique, CloudFormation will always fail when creating a new `ListenerRule` to replace the existing one, unless you change the `priority` as well as the logicalId.

packages/aws-cdk-lib/aws-elasticloadbalancingv2/lib/alb/application-listener.ts

@@ -664,15 +664,21 @@ abstract class ExternalApplicationListener extends Resource implements IApplicat
    * It is not possible to add a default action to an imported IApplicationListener.
    * In order to add actions to an imported IApplicationListener a `priority`
    * must be provided.
+   *
+   * If you previously deployed a `ListenerRule` using the `addTargetGroups()` method
+   * and need to migrate to using the more feature rich `addAction()`
+   * method, then you will need to set the `removeRuleSuffixFromLogicalId: true`
+   * property here to avoid having CloudFormation attempt to replace your resource.
    */
   public addAction(id: string, props: AddApplicationActionProps): void {
     checkAddRuleProps(props);
 
     if (props.priority !== undefined) {
+      const ruleId = props.removeSuffix ? id : id + 'Rule';
       // New rule
       //
       // TargetGroup.registerListener is called inside ApplicationListenerRule.
-      new ApplicationListenerRule(this, id + 'Rule', {
+      new ApplicationListenerRule(this, ruleId, {
         listener: this,
         priority: props.priority,
         ...props,
@@ -807,6 +813,19 @@ export interface AddApplicationActionProps extends AddRuleProps {
    * Action to perform
    */
   readonly action: ListenerAction;
+  /**
+   * `ListenerRule`s have a `Rule` suffix on their logicalId by default. This allows you to remove that suffix.
+   *
+   * Legacy behavior of the `addTargetGroups()` convenience method did not include the `Rule` suffix on the logicalId of the generated `ListenerRule`.
+   * At some point, increasing complexity of requirements can require users to switch from the `addTargetGroups()` method
+   * to the `addAction()` method.
+   * When migrating `ListenerRule`s deployed by a legacy version of `addTargetGroups()`,
+   * you will need to enable this flag to avoid changing the logicalId of your resource.
+   * Otherwise Cfn will attempt to replace the `ListenerRule` and fail.
+   *
+   * @default - use standard logicalId with the `Rule` suffix
+   */
+  readonly removeSuffix?: boolean;
 }
 
 /**

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

@@ -1698,6 +1698,47 @@ describe('tests', () => {
     }).toThrow(/Specify at most one/);
   });
 
+  describe('Rule suffix for logicalId', () => {
+    const identifierToken = 'SuperMagicToken';
+    interface TestCase {
+      readonly removeSuffix?: boolean;
+      readonly expectedLogicalId: string;
+    };
+    const nonDefaultTestCases: TestCase[] = [
+      { removeSuffix: true, expectedLogicalId: identifierToken },
+      { removeSuffix: false, expectedLogicalId: identifierToken + 'Rule' },
+    ];
+    test.each<TestCase>([
+      // Default is consistent, which means it has the `Rule` suffix. This means no change from legacy behavior
+      { removeSuffix: undefined, expectedLogicalId: identifierToken + 'Rule' },
+      ...nonDefaultTestCases,
+    ])('addAction %s', ({ removeSuffix, expectedLogicalId }) => {
+      // GIVEN
+      const app = new cdk.App();
+      const stack = new cdk.Stack(app, 'TestStack', { env: { account: '123456789012', region: 'us-east-1' } });
+      const vpc = new ec2.Vpc(stack, 'Stack');
+      const targetGroup = new elbv2.ApplicationTargetGroup(stack, 'TargetGroup', { vpc, port: 80 });
+      const listener = elbv2.ApplicationListener.fromLookup(stack, 'a', {
+        loadBalancerTags: {
+          some: 'tag',
+        },
+      });
+
+      // WHEN
+      listener.addAction(identifierToken, {
+        action: elbv2.ListenerAction.weightedForward([{ targetGroup, weight: 1 }]),
+        conditions: [elbv2.ListenerCondition.pathPatterns(['/fake'])],
+        priority: 42,
+        removeSuffix,
+      });
+
+      // THEN
+      const applicationListenerRule = listener.node.children.find((v)=> v.hasOwnProperty('conditions'));
+      expect(applicationListenerRule).toBeDefined();
+      expect(applicationListenerRule!.node.id).toBe(expectedLogicalId);
+    });
+  });
+
   describe('lookup', () => {
     test('Can look up an ApplicationListener', () => {
       // GIVEN