![const lambda = require('mambda');
const jsonBodyParser = require('mambda/middlewares/json-body-parser');
const httpErrorHandler = require('mambda/middlewares/http-error-handler');
async function myAsyncHandler(event, context, callback) {
// try {
// const body = headers['Content-Type'] === 'application/json')
// ? JSON.parse(event.body)
// : {}
// } catch (error) {
// other error handling...
// return { statusCode: 422, body: 'Unprocessable entity, invalid json in request body' }
// }
const body = event.body; // A javascript object from the deserialized json in the original event
const foo = await bar();
//... function code
return someOperation(foo);
}
exports.handler = lambda(myAsyncHandler)
.use(jsonBodyParser())
.use(httpErrorHandler())](https://image.slidesharecdn.com/serverlessapiswithjavascript-mattsearle-chocpanda-190712093031/85/Serverless-APIs-with-JavaScript-Matt-Searle-ChocPanda-18-320.jpg)
![const mambda = require('mambda');
const { jsonBodyParser, httpErrorHandler, httpHeaderNormalizer } = require('mambda/middlewares');
const optionsRequestInterceptor = require('./options-request-interceptor');
module.exports = fn => {
const { init, handler = fn } = fn;
return mambda({
init,
handler,
middlewares: [httpHeaderNormalizer(), jsonBodyParser(), httpErrorHandler(), optionsRequestInterceptor()]
});
};
Preconfigure your middlewares](https://image.slidesharecdn.com/serverlessapiswithjavascript-mattsearle-chocpanda-190712093031/85/Serverless-APIs-with-JavaScript-Matt-Searle-ChocPanda-22-320.jpg)
![const generateUrls = ({ s3Instance }) => ({ body }) => {
const applicationId = uuid.v4();
const urls = body.reduce(
(accumulated, fileName) => ({
...accumulated,
[fileName]: s3Instance.getSignedUrl('putObject', {
Bucket: process.env.S3_BUCKET,
Key: `${applicationId}/${fileName}`,
Expires: 120
})
}),
{}
);
return { statusCode: 200, body: JSON.stringify({ applicationId, urls }) };
};
exports.post = lambdaWrapper({
init: () => ({
s3Instance: new S3({
signatureVersion: 'v4'
})
}),
handler: generateUrls
});
● Initialised connection to the s3 API
● Deserialised request body
● Cold start initialisation](https://image.slidesharecdn.com/serverlessapiswithjavascript-mattsearle-chocpanda-190712093031/85/Serverless-APIs-with-JavaScript-Matt-Searle-ChocPanda-23-320.jpg)
Serverless APIs with JavaScript - Matt Searle - ChocPanda
- 1. Serverless APIs with JavaScript Matt Searle ChocPanda
- 2. ● Brief intro to serverless ● AWS Serverless technologies ● API Gateway ● Lambda Functions ● Best Practices ● Mambda ● Example Road map
- 4. THERE IS A SERVER! When discussing serverless technologies, what we’re really talking about is shifting more of your operational responsibilities to a cloud provider. Serverless simply means that you the developer or your friend the infrastructure engineer are no longer responsible for grunt work like provisioning and patching operating systems of servers and scheduling downtime/failover. There is a person somewhere in a data centre managing that server for you and you don’t need to know about it
- 5. Responsibilities Managing/patching the server Scaling resources with demand Load balancing Configuring high availability
- 6. What can I do with this?
- 7. Some of the Serverless tech on AWS Lambda Fargate SNS EFSAppSync AuroraAthena Kinesis
- 8. What is the gateway? The gateway is an entry point for your application, allowing you to create, publish, maintain, monitor, and secure APIs at any scale. Client applications can use the gateway to access backend services, data or business logic by accessing a RESTful or WebSocket API in Gateway. API Gateway
- 9. Lambda What is Lambda and what’s cool about it? Lambdas are small independent units of code that literally are a single function. They’re executed in an entirely managed runtime, meaning you simply upload the executable and trigger them.
- 12. Mobile backend
- 13. Best practices When writing code for lambda
- 14. ● Separate the core logic of your function from the boilerplate and other dependencies ● Take advantage of Execution Context reuse, limit the re-initialisation of variables/objects on every invocation ● Minimise your package size Additional reading: DZONE Article AWS Whitepaper ● Control the dependencies in your function's deployment package. AWS provides some, but updates them periodically which could subtly change your code ● Minimise the complexity of your dependencies. Prefer simpler frameworks that load quickly on Execution Context startup ● There are concurrency limits to be aware of and by default these are global in your AWS account. Prefer function-specific reserved resources A few best practices when writing lambdas
- 15. ● Cold start versus warm start execution performance ● Improving cold start performance is looking at the runtime environment. JS and other interpreted languages have the advantage here ● Small executables for v8 optimisations. Minify and uglify your code, removing comments and anything unnecessary Considerations
- 16. Shameless self-promotion Other tools and libraries do exist I have created a small lightweight tool which leverages a middleware pattern to abstract out boilerplate code from your Lambdas. Inspired by MiddyJS Mambda ChocPanda
- 18. const lambda = require('mambda'); const jsonBodyParser = require('mambda/middlewares/json-body-parser'); const httpErrorHandler = require('mambda/middlewares/http-error-handler'); async function myAsyncHandler(event, context, callback) { // try { // const body = headers['Content-Type'] === 'application/json') // ? JSON.parse(event.body) // : {} // } catch (error) { // other error handling... // return { statusCode: 422, body: 'Unprocessable entity, invalid json in request body' } // } const body = event.body; // A javascript object from the deserialized json in the original event const foo = await bar(); //... function code return someOperation(foo); } exports.handler = lambda(myAsyncHandler) .use(jsonBodyParser()) .use(httpErrorHandler())
- 19. The life of a Mambda function
- 20. const lambda = require('mambda'); const AWS = require('aws-sdk') const myHandler = s3 => (event, context, callback) => { var params = { Bucket: process.env.BUCKET_NAME, Key: process.env.BUCKET_KEY, Body: process.env.BODY }; // function code... s3.putObject(params, function(err, data) { if (err) { callback(err) } else { callback(null, 'Put the body into the bucket! YAY!') } }); } exports.handler = lambda({ init: () => new AWS.S3(), handler: myHandler });
- 21. Simple Recruitment tool ● 2 Javascript front ends hosted as static websites within S3 buckets ● Uses a lambda to create signed urls to upload CVs to another s3 bucket ● Uses lambda to send an SNS notification to the hiring manager when a new candidate applies for a role ● Store the candidate’s name and any other information in a DynamoDb database
- 22. const mambda = require('mambda'); const { jsonBodyParser, httpErrorHandler, httpHeaderNormalizer } = require('mambda/middlewares'); const optionsRequestInterceptor = require('./options-request-interceptor'); module.exports = fn => { const { init, handler = fn } = fn; return mambda({ init, handler, middlewares: [httpHeaderNormalizer(), jsonBodyParser(), httpErrorHandler(), optionsRequestInterceptor()] }); }; Preconfigure your middlewares
- 23. const generateUrls = ({ s3Instance }) => ({ body }) => { const applicationId = uuid.v4(); const urls = body.reduce( (accumulated, fileName) => ({ ...accumulated, [fileName]: s3Instance.getSignedUrl('putObject', { Bucket: process.env.S3_BUCKET, Key: `${applicationId}/${fileName}`, Expires: 120 }) }), {} ); return { statusCode: 200, body: JSON.stringify({ applicationId, urls }) }; }; exports.post = lambdaWrapper({ init: () => ({ s3Instance: new S3({ signatureVersion: 'v4' }) }), handler: generateUrls }); ● Initialised connection to the s3 API ● Deserialised request body ● Cold start initialisation
- 24. Some things I haven’t discussed ● Using swagger annotations in the JS code to describe the handler functions and configure the API gateway ● Setting up development stages and using blue-green deployments API Gateway ● Increased testability of the modules for lambda written with Mambda ● Infrastructure as code (Terraform, AWS CDK, Cloudformation, etc...)
- 25. Any questions?