docs(examples/lambda): added new lambda example

examples/lambda/.gitignore

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+*.js
+!jest.config.js
+*.d.ts
+node_modules
+
+# CDK asset staging directory
+.cdk.staging
+cdk.out
+
+# project specific
+response.json

examples/lambda/.npmignore

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+*.ts
+!*.d.ts
+
+# CDK asset staging directory
+.cdk.staging
+cdk.out

examples/lambda/README.md

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+# Lambda Function
+
+Create a basic Lambda function that can be invoked using the `aws-cli` or AWS Console.
+
+## Getting started
+
+Run `npm install` to get setup.
+
+Have a look at the Lambda code in `./src/index.ts`. Maybe change the returned text to make it more personal. Also have a look at the values in `input.json`, we will use this later.
+
+Once you are happy, deploy your app with `npx cdk deploy`. If you haven't used the CDK in your account before, you will have bootstrap the account first (typically by running `npx cdk bootstrap`) and sort out permissions. Please refer to [the official AWS CDK documentation](https://docs.aws.amazon.com/cdk/latest/guide/home.html) to get started.
+
+As part of the deployment, the ARN of your function will be displayed. We need this for the next step.
+
+To test your function, you could either go into the AWS Console and paste the contents of `input.json` into the test feature.
+
+Alternatively, let's use the aws-cli to invoke our function from the command line:
+
+```bash
+aws lambda invoke --function-name "<YOUR LAMBDA ARN HERE>" --payload fileb://input.json response.json
+```
+
+You will get a response containing the status of our request. Now check our `response.json` for the results:
+
+```bash
+cat response.json
+```
+
+Don't forget to tear everything down with `npx cdk destroy` - otherwise you might occur costs.
+
+## Useful commands
+
+- `npm install` start with this
+- `npm test` perform the jest unit tests
+- `npm start` serve the website on localhost
+- `npx cdk bootstrap` setup your AWS environment
+- `npx cdk deploy` deploy this stack to your default AWS account/region
+- `npx cdk destroy` destroy this stack to ensure you don't occur any costs
+- `npx cdk diff` compare deployed stack with current state
+- `npx cdk synth` emits the synthesized CloudFormation template

examples/lambda/cdk.json

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+{
+  "app": "npx ts-node --prefer-ts-exts infrastructure/app.ts",
+  "context": {
+    "@aws-cdk/core:enableStackNameDuplicates": "true",
+    "aws-cdk:enableDiffNoFail": "true",
+    "@aws-cdk/core:stackRelativeExports": "true",
+    "@aws-cdk/aws-ecr-assets:dockerIgnoreSupport": true,
+    "@aws-cdk/aws-secretsmanager:parseOwnedSecretName": true,
+    "@aws-cdk/aws-kms:defaultKeyPolicies": true,
+    "@aws-cdk/aws-s3:grantWriteWithoutAcl": true,
+    "@aws-cdk/aws-ecs-patterns:removeDefaultDesiredCount": true
+  }
+}

examples/lambda/infrastructure/app.ts

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+#!/usr/bin/env node
+import * as cdk from "@aws-cdk/core";
+import { LambdaStack } from "./stack";
+
+const app = new cdk.App();
+new LambdaStack(app, "Function");

examples/lambda/infrastructure/stack.ts

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+import * as cdk from "@aws-cdk/core";
+import { Function, Runtime } from "@aws-cdk/aws-lambda";
+import { TypeScriptCode } from "@mrgrain/cdk-esbuild";
+
+export class LambdaStack extends cdk.Stack {
+  constructor(scope?: cdk.Construct, id?: string, props?: cdk.StackProps) {
+    super(scope, id, props);
+
+
+    const lambda = new Function(this, "Lambda", {
+      runtime: Runtime.NODEJS_14_X,
+      handler: 'index.handler',
+      code: new TypeScriptCode("./src/index.tsx"),
+    });
+
+    new cdk.CfnOutput(this, "LambdaArn", {
+      value: lambda.functionArn,
+    });
+  }
+}

examples/lambda/input.json

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+{
+    "colour": "green",
+    "food": "pizza",
+    "season": "winter"
+}

examples/lambda/jest.config.js

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+module.exports = {
+  roots: ['<rootDir>/test'],
+  testMatch: ['**/*.test.ts'],
+  transform: {
+    '^.+\\.tsx?$': 'ts-jest'
+  }
+};