Difference between revisions of "NodeJs"
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+ | =Install Node.js= | ||
+ | If you’ve never worked with Node.js before, kick off with installing the npm manager: [https://nodejs.org/en/download/package-manager/ nodejs.org/en/download/package-manager] | ||
+ | |||
+ | ==Install NPM and Express Framework== | ||
+ | In addition to npm, our application will use the Express Framework, one of the most popular Node.js frameworks. Create a new directory and initialize npm: | ||
+ | <source> | ||
+ | $ mkdir helloworld | ||
+ | $ cd helloworld | ||
+ | $ npm init | ||
+ | </source> | ||
+ | |||
+ | When asked for the details of the application (name, version, etc.), just confirm the default values with enter. | ||
+ | |||
+ | Npm will create a '''package.json''' that will hold the dependencies of the app. Let’s add the Express Framework as the first dependency: | ||
+ | |||
+ | <source> | ||
+ | $ npm install express --save | ||
+ | </source> | ||
+ | The file should look like this now: | ||
+ | <syntaxhighlight lang="java"> | ||
+ | { | ||
+ | "name": "helloworld", | ||
+ | "version": "1.0.0", | ||
+ | "description": "", | ||
+ | "main": "index.js", | ||
+ | "scripts": { | ||
+ | "test": "echo \"Error: no test specified\" && exit 1" | ||
+ | }, | ||
+ | "author": "", | ||
+ | "license": "ISC", | ||
+ | "dependencies": { | ||
+ | "express": "^4.15.2" | ||
+ | } | ||
+ | } | ||
+ | </syntaxhighlight> | ||
+ | |||
+ | ==Details of Hello World== | ||
+ | |||
+ | With everything installed, we can create an '''index.js''' file with a simple HTTP server that will serve our Hello World website: | ||
+ | |||
+ | <syntaxhighlight lang="javascipt"> | ||
+ | //Load express module with `require` directive | ||
+ | var express = require('express') | ||
+ | var app = express() | ||
+ | |||
+ | //Define request response in root URL (/) | ||
+ | app.get('/', function (req, res) { | ||
+ | res.send('Hello World!') | ||
+ | }) | ||
+ | |||
+ | //Launch listening server on port 8081 | ||
+ | app.listen(8081, function () { | ||
+ | console.log('app listening on port 8081!') | ||
+ | }) | ||
+ | </syntaxhighlight> | ||
+ | |||
+ | ==Run the app== | ||
+ | The application is ready to launch: | ||
+ | |||
+ | <source> | ||
+ | $ node index.js | ||
+ | </source> | ||
+ | |||
+ | Go to '''http://localhost:8081/''' in your browser to view it. | ||
+ | |||
+ | |||
+ | |||
+ | |||
Revision as of 01:36, 6 November 2018
Contents
Install Node.js
If you’ve never worked with Node.js before, kick off with installing the npm manager: nodejs.org/en/download/package-manager
Install NPM and Express Framework
In addition to npm, our application will use the Express Framework, one of the most popular Node.js frameworks. Create a new directory and initialize npm:
$ mkdir helloworld
$ cd helloworld
$ npm init
When asked for the details of the application (name, version, etc.), just confirm the default values with enter.
Npm will create a package.json that will hold the dependencies of the app. Let’s add the Express Framework as the first dependency:
$ npm install express --save
The file should look like this now:
{
"name": "helloworld",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1"
},
"author": "",
"license": "ISC",
"dependencies": {
"express": "^4.15.2"
}
}
Details of Hello World
With everything installed, we can create an index.js file with a simple HTTP server that will serve our Hello World website:
//Load express module with `require` directive
var express = require('express')
var app = express()
//Define request response in root URL (/)
app.get('/', function (req, res) {
res.send('Hello World!')
})
//Launch listening server on port 8081
app.listen(8081, function () {
console.log('app listening on port 8081!')
})
Run the app
The application is ready to launch:
$ node index.js
Go to http://localhost:8081/ in your browser to view it.
Express Microservice Starter
https://www.npmjs.com/package/express-microservice-starter
An express-based bootstrapping module for building microservices with Node.js. The starter utilises sub-app mounting to provide any implementing express application with a variety of functionality.
Key Features
The starter provides the following features out of the box;
- CORS support
- Cache-Control header support
- Body-parsing support
- Configurable controller/route auto-scanning
- Configurable health monitors
- Configurable per-application logging
- Automatic service registration with ZooKeeper
- Actuator info and health endpoints (/info and /health)
- Partial Response Powered by express-partial-response
- Request correlation id support (res.locals.correlationId and req.log Bunyan child logging also provided)
Basic Usage
The following is the most basic usage of the starter, for a more detailed example please refer to the example directory;
'use strict';
var express = require('express');
var micro = require('express-microservice-starter');
var app = express();
app.use(micro({ discoverable: false, debug: true }));
app.listen(8000, function onListen() {
log.info('Microservice initialised and accepting requests at the following root: http://localhost:8000/starter/v1');
});
app.on('service:registered', function(data) {
log.info('service registered with zookeeper', data);
log.info('microservice registration data is also available as an app.locals property', app.locals.microservice);
});
Configuration
By placing an app.yml config file in the /config directory of an implementing app it is possible to override default options.
default:
#
# Basic
#
server:
port: 8000
#
# Log
#
log:
path: my-log-file.log
#
# Microservice
#
microservice:
basePath: services
server:
name: starter/v1
dependencies: my/other/service/to/monitor/v1
registrationNetworkInterfacePriority:
- en0
- lo0
#
# Zookeeper
#
zookeeper:
connectionString: localhost:2181
retry:
wait: 1000
count: 5
In the above example the application would be accessible at the following address: http://0.0.0.0:8000/starter/v1, with the /actuator/info and /actuator/health diagnostic endpoints activated.
Note: the registrationNetworkInterfacePriority property allows the selection of the network interface when dynamically registering a service with ZooKeeper.
Note: if registrationNetworkInterfacePriority doesn't work for you, you can set ADVERTISED_HOST and ADVERTISED_PORT environment variable.
If you would like to override the version which is exposed in the /info endpoint, just set the VERSION node env variable.
VERSION=1.0.1 node index.js
API
app.use(micro([options]));
options is an optional argument which can overwrite the defaults. It can take the following properties;
- debug: boolean Activate finer grained logging.
- discoverable: boolean Register the service with Zookeeper to allow for discovery by other services connecting to the same instance of Zookeeper.
- controllersPath: String Path to load controllers. Defaults to controllers.
- monitorsPath: String Path to load monitors. Defaults to monitors.
- partialResponseQuery: String The query parameter to use for partial reponse. Defaults to fields.
- correlationHeaderName: String The name of your correlation header. Defaults to X-CorrelationID.
- validatorOptions: object Enable express-validator with these options. Defaults to null.
- enableBodyParsing: boolean Enable or disable body parsing, useful to disable when dealing with content other than JSON. Enables express-validator. Defaults to true.
- enableEtag: boolean Activate etag. Defaults to false.
- enableRequestTracing: boolean Enabled request log trace. Defaults to false.
SWAGGER Integration
Supports binding of route handlers using a swagger specification document via the options.swaggerConfig object.
app.js
'use strict';
var express = require('express');
var micro = require('express-microservice-starter');
var app = express();
var options = {
swaggerConfig: {
filePath: `/swagger.yml`, // path to swagger specification file
controllers: `lib/controllers` // path to controllers directory
}
};
app.use(micro(options));
// to register application specific exception handlers wait until the
// 'swagger:routes:registered' event is emitted.
app.once('swagger:routes:registered', () => {
app.use(function (err, req, res, next) {
if (err) {
res.status(418).json({
name: 'Teapot',
message: 'Always wanted to use this...'
});
}
});
});
app.listen(8000, function onListen() {
log.info('Microservice initialised and accepting requests at the following root: http://localhost:8000/starter/v1');
});
swagger.yml
swagger: "2.0"
info:
version: 1.0.0
title: "API specification"
description: API specification
basePath: /v1
schemes:
- http
consumes:
- application/json
produces:
- application/json
paths:
/users:
x-swagger-router-controller: users # lib/controllers/users
get:
description: Return a list of users
operationId: find
responses:
200:
description: User Response
schema:
type: array
items:
$ref: '#/definitions/User'
default:
description: Standard Error Response
schema:
$ref: '#/definitions/Error'
/users/{uuid}:
x-swagger-router-controller: users # lib/controllers/users
get:
description: Return a user based on the provided uuid
operationId: get
parameters:
- name: uuid
in: path
description: UUID of the user to return
required: true
type: integer
format: int64
responses:
200:
description: Item Response
schema:
$ref: '#/definitions/User'
default:
description: Standard Error Response
schema:
$ref: '#/definitions/Error'
definitions:
User:
required:
- uuid
- name
- status
- created
properties:
uuid:
type: string
name:
type: string
status:
type: string
enum:
- active
- inactive
created:
type: string
format: date-time
lib/controllers/users.js
'use strict';
const user = {
uuid: '1234567890',
name: 'User One',
status: 'active',
created: new Date('2000-01-01')
};
exports.find = function find (req, res, next) {
try {
res.json([user]);
}
catch (e) {
next(e);
}
}
exports.get = function get (req, res, next) {
try {
res.json(user);
}
catch (e) {
next(e);
}
}