Add custom resource and Lambda

lib/exercise-stack.function.ts

@@ -0,0 +1,84 @@
+import type { CloudFormationCustomResourceEvent, Context } from 'aws-lambda';
+import * as https from 'node:https';
+import * as url from 'node:url';
+
+const physicalResourceId = 'CfnRollbackExercise';
+
+export async function handler(
+  event: CloudFormationCustomResourceEvent,
+  context: Context,
+) {
+  console.log(event);
+  if (event.RequestType === 'Create') {
+    await sendResponse(event, context, 'SUCCESS', {}, physicalResourceId);
+    return;
+  } else if (event.RequestType === 'Update' || event.RequestType === 'Delete') {
+    const causeIssue = context.memoryLimitInMB !== '129';
+    if (causeIssue) {
+      await sendResponse(
+        event,
+        context,
+        'FAILED',
+        { reason: 'The Lambda function must have 129MB of memory' },
+        physicalResourceId,
+      );
+    }
+    await sendResponse(event, context, 'SUCCESS', {}, physicalResourceId);
+    return;
+  }
+}
+
+/***
+ * This function is mostly copied from AWS's documentation
+ * https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/cfn-lambda-function-code-cfnresponsemodule.html
+ */
+function sendResponse(
+  event: CloudFormationCustomResourceEvent,
+  context: Context,
+  responseStatus: 'SUCCESS' | 'FAILED',
+  responseData?: Record<string, unknown>,
+  physicalResourceId?: string,
+  noEcho?: boolean,
+) {
+  return new Promise((resolve, reject) => {
+    const responseBody = JSON.stringify({
+      Status: responseStatus,
+      Reason:
+        responseData?.reason ||
+        'See the details in CloudWatch Log Stream: ' + context.logStreamName,
+      PhysicalResourceId: physicalResourceId || context.logStreamName,
+      StackId: event.StackId,
+      RequestId: event.RequestId,
+      LogicalResourceId: event.LogicalResourceId,
+      NoEcho: noEcho || false,
+      Data: responseData,
+    });
+
+    console.log('Response body:', responseBody);
+
+    const parsedUrl = url.parse(event.ResponseURL);
+    const options = {
+      hostname: parsedUrl.hostname,
+      port: 443,
+      path: parsedUrl.path,
+      method: 'PUT',
+      headers: {
+        'content-type': '',
+        'content-length': responseBody.length,
+      },
+    };
+
+    const request = https.request(options, function (response) {
+      console.log('Status code', response.statusCode);
+      resolve(context.done());
+    });
+
+    request.on('error', function (error) {
+      console.log('send(..) failed executing https.request(..): ' + error);
+      reject(context.done(error));
+    });
+
+    request.write(responseBody);
+    request.end();
+  });
+}

lib/exercise-stack.ts

@@ -8,5 +8,21 @@ export class ExerciseStack extends Stack {
   constructor(scope: Construct, id: string, props?: StackProps) {
     super(scope, id, props);
 
+    const serviceRole = new Role(this, 'serviceRole', {
+      assumedBy: new ServicePrincipal('lambda.amazonaws.com'),
+    });
+
+    const exerciseFunction = new NodejsFunction(this, 'function', {
+      runtime: Runtime.NODEJS_20_X,
+      role: serviceRole,
+    });
+
+    new CustomResource(this, 'exercise', {
+      resourceType: 'Custom::Exercise',
+      properties: {
+        value: Date.now().toString(),
+      },
+      serviceToken: exerciseFunction.functionArn,
+    });
   }
 }