feat(lambda): add domainName prop to FunctionUrl

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

@@ -480,6 +480,15 @@ new CfnOutput(this, 'TheUrl', {
  value: fnUrl.url,
 });
 ```
+To get the domain name from the function url, simply call `domainName` on the `FunctionUrl` construct:
+```ts
+... 
+
+new CfnOutput(this, 'TheDomainName', {
+ value: fnUrl.domainName,
+});
+```
+The .domainName attribute will return the domain name (the function url, without the scheme and the trailing slash). For example, if fnUrl.url returns `https://*******.lambda-url.ap-southeast-2.on.aws/`, then fnUrl.domainName will return `*******.lambda-url.ap-southeast-2.on.aws`.
 
 Calls to this URL need to be signed with SigV4.
 

packages/aws-cdk-lib/aws-lambda/lib/function-url.ts

@@ -4,7 +4,7 @@ import { IFunction } from './function-base';
 import { IVersion } from './lambda-version';
 import { CfnUrl } from './lambda.generated';
 import * as iam from '../../aws-iam';
-import { Duration, IResource, Resource } from '../../core';
+import { Duration, Fn, IResource, Resource } from '../../core';
 
 /**
  * The auth types for a function url
@@ -133,9 +133,17 @@ export interface IFunctionUrl extends IResource {
  * The url of the Lambda function.
  *
  * @attribute FunctionUrl
+ * For example `https://*******.lambda-url.ap-southeast-2.on.aws/`
  */
  readonly url: string;
 
+ /**
+ * The domain name of the Lambda Function URL
+ *
+ * For example `*******.lambda-url.ap-southeast-2.on.aws`
+ */
+ readonly domainName: string;
+
  /**
  * The ARN of the function this URL refers to
  *
@@ -243,6 +251,12 @@ export class FunctionUrl extends Resource implements IFunctionUrl {
  }
  }
 
+ get domainName(): string {
+ return Fn.select(
+ 0, Fn.split('/', Fn.select(1, Fn.split('https://', this.url))),
+ );
+ }
+
  public grantInvokeUrl(grantee: iam.IGrantable): iam.Grant {
  return this.function.grantInvokeUrl(grantee);
  }

packages/aws-cdk-lib/aws-lambda/test/function-url.test.ts

@@ -118,6 +118,32 @@ describe('FunctionUrl', () => {
  });
  });
 
+ test('function url domain name', () => {
+ // GIVEN
+ const stack = new cdk.Stack();
+ const fn = new lambda.Function(stack, 'MyLambda', {
+ code: new lambda.InlineCode('hello()'),
+ handler: 'index.hello',
+ runtime: lambda.Runtime.NODEJS_14_X,
+ });
+ const aliasName = 'prod';
+ const alias = new lambda.Alias(stack, 'Alias', {
+ aliasName,
+ version: fn.currentVersion,
+ });
+
+ // WHEN
+ const url = new lambda.FunctionUrl(stack, 'FunctionUrl', {
+ function: alias,
+ });
+
+ // THEN
+ const resolved = stack.resolve(stack.toJsonString({ token: url.domainName }));
+ expect(resolved).toEqual({
+ 'Fn::Join': ['', ['{"token":"', { 'Fn::Select': [0, { 'Fn::Split': ['/', { 'Fn::Select': [1, { 'Fn::Split': ['https://', { 'Fn::GetAtt': ['FunctionUrl84B92DCA', 'FunctionUrl'] }] }] }] }] }, '"}']],
+ });
+ });
+
  test('throws when configured with Version', () => {
  // GIVEN
  const stack = new cdk.Stack();