Portable Serverless Apps

ServerlessDays, London, July 6th, 2018

Can you design serverless applications that run in multiple environments, for example having the same code executed in AWS Lambda and Docker containers? Or the same business logic being triggered via an API or while processing a real-time stream of data? In this session, we’ll review some best practices that make serverless development more readable, testable and reusable.

Transcript

1. Portable Serverless Apps
   Danilo Poccia
   Evangelist, Serverless
   Amazon Web Services
   @danilop
   danilop
   danilop@amazon.com
   

   View Slide

2. Serverless is for Builders
   

   View Slide

3. How to Build a
   Serverless “Hello World” ?
   

   View Slide

4. "use strict";
   console.log('Loading function');
   exports.handler = async (event, context) => {
   console.log('request: ' + JSON.stringify(event));
   let name; // default value is undefined
   if (event.queryStringParameters != null) {
   name = event.queryStringParameters.name;
   }
   console.log('name: ', name);
   if ((name == undefined) || (name == '')) {
   name = 'World';
   }
   const greetings = 'Hello ' + name + '!';
   console.log('greetings: ', greetings);
   const responseCode = 200;
   const responseBody = {
   message: greetings;
   };
   const response = {
   statusCode: responseCode,
   headers: {
   'Content-Type': 'application/json'
   },
   body: JSON.stringify(responseBody)
   };
   console.log('response: ' + JSON.stringify(response));
   return buildResponse();
   };
   { “message": "Hello Danilo!” }
   { “message": "Hello World!” }
   

   View Slide

5. Event Function
   Your
   Business
   Logic
   Share
   Result
   

   View Slide

6. “use strict";
   console.log('Loading function');
   // Your business logic
   function greetingsFor(name) {
   console.log('name: ', name);
   if ((name == undefined) || (name == '')) {
   name = 'World';
   }
   const greetings = 'Hello ' + name + '!';
   console.log('greetings: ', greetings);
   return greetings;
   }
   // Event wrapper for Amazon API Gateway
   exports.handler = async (event, context) => {
   let buildResponse = (message) => {
   const responseCode = 200;
   const responseBody = {
   message: message
   };
   const response = {
   statusCode: responseCode,
   headers: {
   'Content-Type' : 'application/json'
   },
   body: JSON.stringify(responseBody)
   };
   console.log('response: ' +
   JSON.stringify(response));
   return response;
   };
   console.log('request: ' + JSON.stringify(event));
   let name; // default value is undefined
   if (event.queryStringParameters != null) {
   name = event.queryStringParameters.name;
   }
   return buildResponse(greetingsFor(name));
   };
   // If not running on AWS Lambda, use Express
   if (!(process.env.LAMBDA_TASK_ROOT &&
   process.env.AWS_EXECUTION_ENV)) {
   const express = require('express');
   const app = express();
   let buildResponse = (message) => {
   const responseBody = {
   message: message
   };
   const response = JSON.stringify(responseBody);
   console.log('response: ' + response);
   return response;
   };
   app.get('/', function (req, res) {
   res.send(
   buildResponse(greetingsFor(req.query.name))
   );
   });
   console.log("Listening...");
   app.listen(process.env.PORT || 3000);
   }
   Business Logic Event Wrapper Web Interface
   

   View Slide

7. Business Logic
   Docker
   Container
   AWS Lambda
   

   View Slide

8. "use strict";
   console.log('Loading function');
   // Your business logic
   function greetingsFor(name) {
   console.log('name: ', name);
   if ((name == undefined) || (name == '')) {
   name = 'World';
   }
   const greetings = 'Hello ' + name + '!';
   console.log('greetings: ', greetings);
   return greetings;
   }
   "use strict";
   const app = require('../../app.js');
   const chai = require('chai');
   const expect = chai.expect;
   var event, context;
   describe('Tests index', function () {
   it('verifies successful response', async () => {
   const result = await app.lambda_handler(event, context, (err, result) => {
   expect(result).to.be.an('object');
   expect(result.statusCode).to.equal(200);
   expect(result.body).to.be.an('string');
   let response = JSON.parse(result.body);
   expect(response).to.be.an('object');
   expect(response.message).to.be.equal("Hello World!”);
   expect(response.location).to.be.an("string");
   });
   });
   });
   Business Logic Unit Tests
   

   View Slide

9. Event
   Context
   Function
   Your
   Business
   Logic
   Share
   Result
   Unit Test
   

   View Slide

10. greetingsFor.js
    event_APIGateway.js
    event_Kinesis.js
    app.js
    Platform Business Logic
    Adapter
    Amazon

    API Gateway
    Kinesis
    Data Stream
    Users
    Docker
    Container
    

    View Slide

11. Portable App
    Clean Code
    Segregation of Concerns
    Adapter Pattern
    

    View Slide

12. Portable Serverless Apps
    Danilo Poccia
    Evangelist, Serverless
    Amazon Web Services
    @danilop
    danilop
    danilop@amazon.com
    

    View Slide