consul-demo

const express = require('express')
var request = require('request');
const http = require('http');
var fs = require('fs');
const app = express();

const port = 3000;
const ID_PREFIX = 'QC-TASK-';
const OBJECTS = ['Object1', 'Object2', 'Object3', 'Object4', 'Object5'];

app.listen(port, () => console.log(`App listening on port ${port}!`));

app.get('/register:id', (req, res) => {
    const id = ID_PREFIX + req.params.id;
    console.log('Task: ' + id + ' is being register as a new service');

    const tags = ['qc' + id, 'dev'];
    const data = getServiceJSON(id, tags);

    registerService(id, data);

    res.send(id + ' successfully registered.');
});

app.get('/deregister:id', (req, res) => {
    const id = ID_PREFIX + req.params.id;
    console.log('My work (' + id + ') here is done.\nI will now gracefully deregister now');
    deregisterService(id);
    res.send('Deregistered ' + id);
});

app.get('/healthcheck:id', (req, res) => {
    const id = req.params.id.split('-')[2];
    if (id % 2 == 0) {
        res.send('Working on objects...' + OBJECTS);
    } else if (id % 3 == 0) {
        res.sendStatus(404);
    } else {
        res.sendStatus(200);
    }
});

app.get('/box-healthcheck', (req, res) => {
    const id = parseInt((Math.random() * 100), 10);
    if (id % 2 == 0) {
        res.sendStatus(500);
    } else {
        res.sendStatus(200);
    }
});

app.get('/healthcheck', (req, res) => {
    res.send('Loading Objects...');
});

/*
Helpers
*/

/**
 * Method to register a new service
 * @param {string} id - unique id of the new service
 * @param {JSON} data - service configuration
 */
function registerService(id, data) {
    const options = getOptions('/v1/agent/service/register');
    makeHTTPRequest(options, data);
}

/**
 * Method to deregister a service by its unique ID
 * @param {string} id - unique ID of the service we wish to deregister
 */
function deregisterService(id) {
    const options = getOptions('/v1/agent/service/deregister/' + id);
    makeHTTPRequest(options);
}

/**
 * Method to execute HTTP Request based on options and data passed
 * @param {JSON} options - containing HTTP params
 * @param {JSON} data - that should be sent 
 */
function makeHTTPRequest(options, data = JSON.stringify({})) {
    const req = http.request(options, (res) => {
        // console.log(`statusCode: ${res.statusCode}`);a
        res.on('data', (d) => {
            process.stdout.write(d);
        });
    });
    req.on('error', (error) => {
        console.error(error);
    });
    req.write(data);
    req.end();
}

/**
 * Method to return a JSON object containing data for HTTP request to the consul server
 * @param {string} path 
 */
function getOptions(path) {
    const options = {
        hostname: 'localhost',
        port: 8500,
        path: path,
        method: 'PUT',
        headers: {
            'Content-Type': 'application/json'
        }
    };
    return options;
}

/**
 * Method to generate configuration of the service
 * @param {string} id - unique ID of the service
 * @param {array} tags - tags by which services can be searched 
 */
function getServiceJSON(id, tags) {
    const data = JSON.stringify({
        Name: id,
        ID: id,
        port: 20,
        Tags: tags,
        Checks: [
            {
                Id: id,
                Name: 'Objects still being generated on ' + id,
                Interval: '5s',
                HTTP: 'http://localhost:3000/healthcheck' + id
            },
            {
                Id: id,
                Name: 'All secondary tasks running ' + id,
                Interval: '5s',
                HTTP: 'http://localhost:3000/box-healthcheck'
            }
        ]
    });
    return data;
}