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Learn Hapi

Happiness is learning how to use the Hapi.js (Node.js) web framework to build reliable/scalable apps faster.

What is Hapi?

Hapi is the framework for rapidly building RESTful & Real-Time web applications and services with Node.js. <br /> Whether you are building a very simple API for your website/mobile app or a large scale, cache heavy, secure e-commerce website, hapi has you covered. Hapi will help get your server developed quickly with its wide range of configurable options.

Watch this intro/background to Hapi video:

What is Hapi?

Most people/teams that have tried Hapi have embraced Hapi to build complete web applications. But if you are only building a REST API (e.g. for a mobile app) please read: https://github.com/dwyl/learn-api-design

Why Hapi instead of XYZ framework?

Q: I already know how to build REST APIs in {framework-xyz} why learn a new framework? <br /> A: If you are happy with your existing system & level of team productivity, stick with what you know. If not, learn [how to be] Hapi. (We have built Sites/APIs with both Express, Restify, Sails & Meteor and find Hapi has solved more "real world" problems and thus we end up writing less code. YMMV. See benefits below)

Q: Hapi looks like quite a steep learning curve, how long will it take me to learn? <br /> A: You can get started immediately with the examples below, it will take approximately 60 mins to complete them all (after that add a couple of hours to read/learn further). The most important part is to try Hapi on a simple project to gain experience/confidence.

Key Benefits

In-depth Comparison to Express.js

@ethanmick wrote a detailed post on why he prefers Hapi to Express: https://www.ethanmick.com/why-i-like-hapi-more-than-express/ --its worth a read. PDF

Beginner Friendly Examples/Apps to Learn From/With

We have a few "beginner" example apps (with documentation & tests!) that will help you get started with something a bit more "real world":

For a list of examples see: https://github.com/dwyl?&query=example

Who (is using Hapi) ? contributions welcome

The list of teams using Hapi.js to build their node.js apps grows every day! See: https://hapijs.com/community

While you should not make your decisions to use a given technology based on who else is using it, you should be aware that and if you need to answer the question: "Who is already using this in Production?" it's really useful to have a good list.

How?! (Dive In!)

Requirements

Optional

(Not essential before you start, however) You will benefit from having:

Make Me Hapi ("Official" Beginner Workshop)

First thing you should do to get familiar with Hapi is work through the makemehapi workshop. <br /> (assumes some node.js prior knowledge but otherwise a gentle self-paced introduction)

Note: makemehapi currently uses Hapi v16. Some major changes were introduced to Hapi in v17. Differences between v16 and v17

Create a new folder on your local machine for your answers to makemehapi:

mkdir makemehapi && cd makemehapi

Install the workshop:

npm install -g makemehapi@latest

( if it fails to install see: https://stackoverflow.com/questions/16151018/npm-throws-error-without-sudo )

Once its installed, start the tutorial with the following command:

makemehapi

Try to complete all challenges.

makemehapi complete

If you get stuck, you can either google for the specific error you are seeing or if you are not "getting" it, you can always look at my answers in the /makemehapi directory of this repository or
the "official" solutions in the /makemehapi/exercises/{exercise-name}/solution directory
e.g: https://github.com/hapijs/makemehapi/tree/master/exercises/hello_hapi/solution

or if you still don't get it, ask us: https://github.com/dwyl/learn-hapi/issues

<hr />

Extended Examples

For the rest of the tutorial we will cover the various plugins and features we have used in the Hapi.js ecosystem that will help you getting up-and-running with Hapi!

Recap: Hello World in Hapi

Once you have completed the makemehapi workshop, on your computer, create a new directory called "hapiapp". e.g:

mkdir hapiapp && cd hapiapp

Type out (or copy-paste) this code into a file called index.js

const Hapi = require('hapi');
const server = new Hapi.Server({port: 3000}); // tell hapi which TCP Port to "listen" on

server.route({
	method: 'GET',        // define the method this route will handle
	path: '/{yourname*}', // this is how you capture route parameters in Hapi
	handler: function(req, h) { // request handler method
		return 'Hello ' + req.params.yourname + '!'; // reply with text.
	}
});

async function startServer() {
  await server.start() // start the Hapi server on your localhost
  console.log('Now Visit: http://localhost:' + server.info.port + '/YOURNAME');
}

startServer();

module.exports = server;

Install Hapi:

npm init -y && npm install hapi --save

Run:

node .

Visit: http://localhost:3000/YOURNAME (in your browser) you should see something like:

hello world in hapi

Validation with Joi

Validation is a fancy way of saying "checking" a value is the type / format and length you expect it to be.

e.g. imagine you ask people to input their phone number and some joker enters letters instead of numbers. The validation will display a message to the person informing the data is incorrect.

Joi is the validation library built by the same team as Hapi. Most people use Joi with Hapi, but given that it is a separate module, plenty of people use Joi independently; its well worth checking it out!

An example: Type out (or copy-paste) this code into a file called hellovalidate.js

// Start this app from your command line with: node hellovalidate.js
// then visit: http://localhost:3000/YOURNAME

const Hapi = require('hapi'),
    Joi  = require('joi');

const server = new Hapi.Server({ port: 3000 });

server.route({
	method: 'GET',
	path: '/{yourname*}',
	config: {  // validate will ensure YOURNAME is valid before replying to your request
		validate: {
			params: {
				yourname: Joi.string().min(2).max(40).alphanum().required()
			}
		},
		handler: function (req, h) {
			return 'Hello '+ req.params.yourname + '!';
		}
	}
});

async function startServer() {
  await server.start(); // start the Hapi server on your localhost
  console.log('Now Visit: http://localhost:' + server.info.port + '/YOURNAME');
}

startServer();

Now try entering an invalid name: http://localhost:3000/T
You should see a Validation Error:

Hapi Joi validation error

This might not look like a "Friendly" Error message. But as we will see later, it provides all the information we need in our Client/App and we can display a more user-friendly error to people.

Joi has many more useful validation methods. We will use a few of them later on when we build our example app.

Testing with Lab

If you're new to Test Driven Development (TDD) read our Beginners' TTD Tutorial: https://github.com/dwyl/learn-tdd (first)
and then come back to this tutorial!

If you've done functional or unit testing in previous programming projects you will be at home with Lab.

Lab borrows heavily from Mocha, so if you followed our learn-mocha tutorial this should all be familiar.

(Using the code we wrote above in the Validation with Joi section with a minor addition) An example of testing with Lab:

const Lab = require("lab");           // load Lab module
const lab = exports.lab = Lab.script(); //export test script
const Code = require("code");		 //assertion library
const server = require("../examples/hellovalidate.js");

lab.experiment("Basic HTTP Tests", function() {
	// tests
	lab.test("GET /{yourname*} (endpoint test)", async function() {
		const options = {
			method: "GET",
			url: "/Timmy"
		};
		// server.inject lets you simulate an http request
		const response = await server.inject(options);
		Code.expect(response.statusCode).to.equal(200);  //  Expect http response status code to be 200 ("Ok")
		Code.expect(response.result).to.have.length(12); // Expect result to be "Hello Timmy!" (12 chars long)
		await server.stop();
	});
});

First we create a test suite for our test Lab.experiment (the first argument is the name of the test suite "Basic HTTP Tests")

Next is a basic test that calls the only route we have /{yourname} in this case GET /Timmy.
We expect to receive a 200 http status code and the response body to be the text "Hello Timmy!".

  1. Create a new directory in your project called test
  2. Create a new file called test.js in the ./test dir
  3. Type out or copy-paste the above code into test.js
  4. Open your package.json file
  5. Add a scripts section to the package.json file with the following:
  "scripts": {
    "test": "lab -c"
  }
  1. Save the package.json file
  2. run the npm test script from your command line to execute the tests

The result should look something like this:

<img width="287" alt="Hapi testing with Lab 100% coverage" src="https://cloud.githubusercontent.com/assets/4185328/10119715/6232f530-6495-11e5-86ef-17d2bd61795a.png">

Note how the test script has a -c (coverage) flag above this give us the code coverage.

We have 100% code coverage so we can move on to our next test/feature!

How do you think we would write a test for an error? (hint: have a look inside ./test/test.js and see the second test :)

Note on Testing: Tape is Simpler than Lab+Code

While Lab is really Good and is the "official" testing framework used by Hapi, we prefer
the simplicity of tape; we find our tests are simpler to write/read/understand. #YMMV Also we prefer to use a separate & specialised module for tracking test coverage: istanbul which we find does a better job at tracking coverage...

The preceding Lab test can be re-written (simplified) in Tape as:

const test   = require('tape');
const server = require("../index.js"); // our index.js from above

test("Basic HTTP Tests - GET /{yourname*}", async function(t) { // t
	const options = {
		method: "GET",
		url: "/Timmy"
	};
	// server.inject lets you similate an http request
	const response = await server.inject(options);
	t.equal(response.statusCode, 200);  //  Expect http response status code to be 200 ("Ok")
	t.equal(response.result.length, 12); // Expect result to be "Hello Timmy!" (12 chars long)
	await server.stop();
	t.end();  // t.end() is required to end the test in tape
});

These tests are functionally equivalent in that they test exactly the same outcome. Decide for yourself which one you prefer for readability and maintainability in your projects.
For our Tape Tutorial see: https://github.com/dwyl/learn-tape

Related Links

Continuous Integration

Making sure your code is working as you expect it to (over time).

Integrating Hapi with Travis CI

If you are new to Travis-CI or need a refresher see: https://github.com/dwyl/learn-travis

We have Travis-CI enabled for all our hapi.js based projects:

So if you need an example to follow, check out our repos!
And as always, if you have any questions, ask!

Error Handling with Boom

Boom makes custom errors easier in Hapi. Imagine you have a page or item of content (photo, message, etc.) that you want to protect from public view (only show to someone who is logged in).

First install boom:

npm install boom --save

Next write another test in ./test/test.js (If you aren't used to "Test First" - trust the process...)

lab.experiment("Authentication Required to View Photo", function() {
    // tests
    lab.test("Deny view of photo if unauthenticated /photo/{id*} ", async function() {
	    const options = {
	        method: "GET",
	        url: "/photo/8795"
	    };
	 	// server.inject lets you simulate an http request
	    const response = await server.inject(options);
      Code.expect(response.statusCode).to.equal(401);  //  Expect http response status code to be 200 ("Ok")
      Code.expect(response.result.message).to.equal("Please log-in to see that"); // (Don't hard-code error messages)
	});
});

When you run npm test you will see a fail:

<img width="809" alt="Hapi auth test fail" src="https://cloud.githubusercontent.com/assets/4185328/10119711/21c84fc2-6495-11e5-8d51-c6df5181e4f4.png">

Next we want to make this test pass and we'll use Boom to get our custom error message.

The wrong way of doing this is to explicitly hard-code the response for this route. The right way is to create a generic route which responds to any request for a photo with any id. And since we don't currently have any authentication set up, we mock (fake) it. (Don't worry we will get to the authentication in the next step...)

const Boom = require('boom');
server.route({
  method: 'GET',
  path: '/photo/{id*}',
  config: {  // validate will ensure `id` is valid before replying to your request
    validate: { params: { id: Joi.string().max(40).min(2).alphanum() } },
    handler: function (req, h) {
        // until we implement authentication we are simply returning a 401:
        return Boom.unauthorized('Please log-in to see that');
        // the key here is our use of the Boom.unauthorised method
    }
  }
});

Our test passes but the point was to show that returning errors with specific messages is easy with Boom.

<img width="504" alt="learn-hapi-clearer-boom-message" src="https://cloud.githubusercontent.com/assets/4185328/10119795/474a8504-6499-11e5-9833-76a4f0fb3818.png">

Have a look at https://github.com/hapijs/boom for more error response options. We will be using these later as we build our app. Let's move on to authentication.

For a more user-friendly approach to error-handling see: https://github.com/dwyl/hapi-error

Logging with good

Application logging can often be an afterthought developers only implement after they have a production bug which is crashing their API/App and they are scrambling to try and "debug" it.

Thankfully, it Hapi has first-class support for logging with the good module.

We have written a little example you can use to get started: examples/hellogood.js

Run it locally with node examples/hellogood.js then visit http://localhost:3000/hello/yourname in your browser.

Note: Good is not yet compatible with Hapi 17, so this code will only run if you are using v16. See here for more details

You should expect to see something like this: learn-hapi-good-log-two-ops

There are good examples including logging use http (e.g. to a 3rd party logging tool) in the Good repo: https://github.com/hapijs/good/tree/master/examples

Again, if you have any questions, ask

Authentication

Authentication is the process of determining whether someone or something is, in fact, who or what it is declared to be.

Authentication (or "Auth") is something many novice (naive?) developers attempt to write themselves. (I was once that kid... trust me, we have bigger fish to fry, use a well-written/tested library!)

We have 4 options:

  1. Google - If you are building an "enterprise" or "education" app which you know will be used in Google-enabled companies/schools we wrote a Hapi plugin: https://github.com/dwyl/hapi-auth-google which lets you include Google Login in your app in a few clear steps. The plugin uses the Official Google Node.js API Client and is written to be as readable as possible for complete beginners.
  2. EveryAuth - Specific to Connect/Express apps: https://github.com/bnoguchi/everyauth
  3. Passport.js - 100% Code Coverage and many excellent integrations https://passportjs.org/guide/providers/
  4. Bell - the 3rd party Login Hapi.js Plugin is good however we found it lacking in documentation/usage examples, which is why we wrote our own (simpler) Auth Plugin specific to our projects. see: https://github.com/dwyl?query=auth

Bell

The go-to solution for 3rd party authentication in hapi is bell: https://github.com/hapijs/bell. There are a few good examples in the repo: https://github.com/hapijs/bell/tree/master/examples.

Caching with Catbox

Most apps don't need caching from "Day 1" (because you don't know upfront where your app's bottlenecks are going to be...).

But, once again, the team that brought you Hapi.js have solved the problem of caching, see: https://github.com/hapijs/catbox/ and https://hapijs.com/tutorials/caching

We use Redis for blazing fast application and data caching. Hapi.js Catbox makes this very easy!

Using Socket.io with Hapi for Real-Time Apps

Using Socket.io with Hapi.js could not be easier! To help you get started we've built a fully-functional chat application with tests (now featured on the hapijs.com Resources page), which demonstrates the power of Real-Time data-synching in your apps.

https://github.com/dwyl/hapi-socketio-redis-chat-example

Hapi v16

There were some major changes introduced to Hapi when version 17 was released. For a full list, see the version 17 release notes, but here are the major differences relevant to this guide:

	var server = new Hapi.server();

and passed our options to:

	server.connection({port: 8000});

Now, we just pass our options straight away, and no longer need to call the connection method:

	const server = new Hapi.server({port: 8000});

	return "your reply";

And the reply parameter to your handler has been replaced with a response toolkit (h) containing helpers from hapi core and your plugins.

Not all of the hapi plugins have been updated to work with v17 yet (For example Bell, and Good), so be careful if you decide to upgrade an existing project.

The previous version of this tutorial and code examples for Hapi 16 can be found here: https://github.com/dwyl/learn-hapi/tree/b58495ea002a9f3f8af8d183f6004d2b483f4591

Please Suggest Improvements! contributions welcome

If you want to extend this tutorial or simply request additional sections, open an issue on GitHub: https://github.com/dwyl/learn-hapi/issues

Background Reading / Watching

Video Intro

Tutorials

Selected StackOverflow Questions & Answers: