koa-microservice

Microservice Server for Koa

Resource	URL
GitHub	https://github.com/lyndonbuckley/koa-microservice
NPM	https://npmjs.com/package/koa-microservice

Intro

This package is a starting point for common functionality used when creating services and APIs using Koa Framework (https://github.com/koajs)

• Multiple Listeners
• Graceful Startup/Shutdown (with support for process messages)
• Built-in Health Check Endpoints/Middleware

Example

import {Microservice} from "koa-extended-server"
import {createConnection, Conection} from "typeorm";

const dbConnection: Connection;
const app = new Microservice();

// open database connection
app.onStartup(async()=>{
    dbConnection = await createConnection();
    return dbConnection.isConnected;
});

// close database connection
app.onShutdown(async() => {
    if (dbConnection.isConnected)
        await dbConnection.close();
    
    return (dbConnection.isConnected ? false : true)
});

// health check
app.addHealthCheck(() => {
    return dbConnection.isConnected;
});

// HTTP listener
app.http(8080);

// start
app.start();

Graceful Startup/Shutdown

onStartup

Perform operations or checks before starting server - Example use cases:

Connect to Database ORM

const dbConnection: Connection;
async function connectToDatabase(): Promise<boolean> {
 dbConnection = await createConnection();
    return dbConnection.isConnected;
}

const app = new Microservice();
app.onStartup(connectToDatabase);

Subscribe to PubSub Topic

import {PubSub} from '@google-cloud/pubsub';
const pubSubClient = new PubSub();
async function subscribe() {
    const sub = await pubSubClient.topic('TOPIC_NAME').createSubscription('UNIQUE_NAME');
    return sub ? true : false;
}

const app = new Microservice({
    onStartup: subscribe
})

Health Checks

Specifying userAgent in options

const app = new Microservice({
    healthCheckEndpoint: '/health-check'
});

Specifying userAgent in options

const app = new Microservice({
    healthCheckUserAgent: 'GoogleHC/1.0'
});

Setting via parameter

const app = new Microservice();
app.healthCheckEndpoint = '/health-check';
app.healthCheckUserAgent = ['GoogleHC/1.0','NS1 HTTP Monitoring Job'];