feat: add api gateway lambda endpoint

Author: tstephen-nhs

.gitignore

@@ -27,3 +27,4 @@ _site/
 .jekyll-metadata
 vendor
 .trivy_out/
+*.tgz

packages/cdkConstructs/src/constructs/RestApiGateway/LambdaEndpoint.ts

@@ -0,0 +1,32 @@
+import {IResource, LambdaIntegration} from "aws-cdk-lib/aws-apigateway"
+import {IRole} from "aws-cdk-lib/aws-iam"
+import {IFunction} from "aws-cdk-lib/aws-lambda"
+import {HttpMethod} from "aws-cdk-lib/aws-lambda"
+import {Construct} from "constructs"
+
+export interface LambdaFunctionHolder {
+  readonly function: IFunction
+}
+
+export interface LambdaEndpointProps {
+  parentResource: IResource
+  readonly resourceName: string
+  readonly method: HttpMethod
+  restApiGatewayRole: IRole
+  lambdaFunction: LambdaFunctionHolder
+}
+
+export class LambdaEndpoint extends Construct {
+  resource: IResource
+
+  public constructor(scope: Construct, id: string, props: LambdaEndpointProps) {
+    super(scope, id)
+
+    const resource = props.parentResource.addResource(props.resourceName)
+    resource.addMethod(props.method, new LambdaIntegration(props.lambdaFunction.function, {
+      credentialsRole: props.restApiGatewayRole
+    }))
+
+    this.resource = resource
+  }
+}

packages/cdkConstructs/src/index.ts

@@ -2,6 +2,7 @@
 export * from "./constructs/TypescriptLambdaFunction.js"
 export * from "./constructs/RestApiGateway.js"
 export * from "./constructs/RestApiGateway/accessLogFormat.js"
+export * from "./constructs/RestApiGateway/LambdaEndpoint.js"
 export * from "./constructs/PythonLambdaFunction.js"
 export * from "./apps/createApp.js"
 export * from "./config/index.js"

packages/cdkConstructs/tests/constructs/RestApiGateway/LambdaEndpoint.test.ts

@@ -0,0 +1,89 @@
+import {App, Stack} from "aws-cdk-lib"
+import {RestApi} from "aws-cdk-lib/aws-apigateway"
+import {Role, ServicePrincipal} from "aws-cdk-lib/aws-iam"
+import {Template, Match} from "aws-cdk-lib/assertions"
+import {Architecture, Function as LambdaFunction, Runtime} from "aws-cdk-lib/aws-lambda"
+import {
+  describe,
+  test,
+  beforeAll,
+  expect
+} from "vitest"
+import {HttpMethod} from "aws-cdk-lib/aws-lambda"
+
+import {LambdaEndpoint} from "../../../src/constructs/RestApiGateway/LambdaEndpoint.js"
+
+describe("LambdaEndpoint construct", () => {
+  let stack: Stack
+  let template: Template
+  let construct: LambdaEndpoint
+
+  beforeAll(() => {
+    const app = new App()
+    stack = new Stack(app, "LambdaEndpointStack")
+
+    const api = new RestApi(stack, "TestApi")
+
+    const credentialsRole = new Role(stack, "ApiGwRole", {
+      assumedBy: new ServicePrincipal("apigateway.amazonaws.com")
+    })
+
+    // Minimal lambda function stub that satisfies LambdaFunctionHolder interface
+    const lambdaFn = new LambdaFunction(stack, "DummyFn", {
+      runtime: Runtime.NODEJS_22_X,
+      handler: "index.handler",
+      code: {
+        bind: () => ({
+          s3Location: {bucketName: "dummy", objectKey: "dummy.zip"}
+        }),
+        bindToResource: () => undefined,
+        isInline: false
+      } as unknown as never,
+      architecture: Architecture.X86_64
+    })
+
+    construct = new LambdaEndpoint(stack, "TestLambdaEndpoint", {
+      parentResource: api.root,
+      resourceName: "test-resource",
+      method: HttpMethod.GET,
+      restApiGatewayRole: credentialsRole,
+      lambdaFunction: {function: lambdaFn}
+    })
+
+    template = Template.fromStack(stack)
+  })
+
+  test("creates an API Gateway resource with the correct path part", () => {
+    template.hasResourceProperties("AWS::ApiGateway::Resource", {
+      PathPart: "test-resource"
+    })
+  })
+
+  test("creates a GET method on the resource", () => {
+    template.hasResourceProperties("AWS::ApiGateway::Method", {
+      HttpMethod: "GET"
+    })
+  })
+
+  test("exposes the resource as a public property", () => {
+    expect(construct.resource).toBeDefined()
+  })
+
+  test("uses credentials role on the Lambda integration", () => {
+    template.hasResourceProperties("AWS::ApiGateway::Method", {
+      HttpMethod: "GET",
+      Integration: Match.objectLike({
+        Type: "AWS_PROXY"
+      })
+    })
+  })
+})
+
+describe("LambdaEndpoint accepts TypescriptLambdaFunction via structural typing", () => {
+  test("LambdaFunctionHolder interface is satisfied by any object with a function property", () => {
+    // This is a compile-time check verified by the build step. Here we just
+    // assert the interface shape is correct at runtime.
+    const holder = {function: {} as unknown as never}
+    expect(holder.function).toBeDefined()
+  })
+})