app.js

var geohash = require("ngeohash");
const config = require("./config.json");
const axios = require("axios");
const Influx = require("influx");

// our metrics
const metricPort = 3001;
const express = require('express')
const app = express()

const Prometheus = require('prom-client')

const apiCallsTotal = new Prometheus.Counter({
    name: 'api_calls_total',
    help: 'Total number of geo-ip calls',
    labelNames: ['status']
});

const apiRequestDurationMicroseconds = new Prometheus.Histogram({
    name: 'api_request_duration_ms',
    help: 'Duration of api requests in ms',
    labelNames: ['response_time'],
    buckets: [0.10, 5, 15, 50, 100, 200, 300, 400, 500]  // buckets for response time from 0.1ms to 500ms
})

  
app.get('/metrics', (req, res) => {
    res.set('Content-Type', Prometheus.register.contentType)
    res.end(Prometheus.register.metrics())
})

console.log("config: " + JSON.stringify(config));
console.log("config.influxHost=" + config.influxHost);
console.log("config.influxDatabase=" + config.influxDatabase);

// TCP handles
const net = require('net');
const port = 8080;
const host = '0.0.0.0';

const server = net.createServer();
server.listen(port, host, () => {
    console.log('TCP Server is running on port ' + port + '.');
});

// // Runs before each requests
// server.use((req, res, next) => {
//     res.locals.startEpoch = Date.now()
//     next()
// })

// // Runs after each requests
// server.use((req, res, next) => {
//     const responseTimeInMs = Date.now() - res.locals.startEpoch

//     requestDurationMicroseconds
//         .labels('response_time')
//         .observe(responseTimeInMs)

//     next()
// })  


// InfluxDB Initialization.
const influx = new Influx.InfluxDB({
    host: config.influxHost,
    database: config.influxDatabase
});

let sockets = [];

const metricsServer = app.listen(metricPort, () => {
    console.log(`Metrics app listening on port ${metricPort}!`)
  })

server.on('connection', function(sock) {
    console.log('CONNECTED: ' + sock.remoteAddress + ':' + sock.remotePort);
    sockets.push(sock);

    sock.on('data', function(data) {
        console.log("Received data: " + data);
        try {
            let message = JSON.parse("" + data)
            // API Initialization.
            const instance = axios.create({
                baseURL: "http://ip-api.com/json"
            });
            instance
                .get(`/${message.ip}?fields=status,lat,lon`)
                .then(function(response) {
                    const apiResponse = response.data;
                    console.log("ip-api.com response: ");
                    console.log("  status: " + apiResponse.status);

                    const success = apiResponse.status === 'success' ? 'success' : 'failure';
                    apiCallsTotal.inc({
                        status: success
                      })
                    
                    console.log("  lat   : " + apiResponse.lat);
                    console.log("  lon   : " + apiResponse.lon);
                    console.log("geohash: "+ geohash.encode(apiResponse.lat, apiResponse.lon));

                    influx.writePoints(
                        [{
                            measurement: "geossh",
                            fields: {
                                value: 1
                            },
                            tags: {
                                geohash: geohash.encode(apiResponse.lat, apiResponse.lon),
                                username: message.username,
                                port: message.port,
                                ip: message.ip
                            }
                        }]
                    );
                    console.log("Intruder added")
                })
                .catch(function(error) {
                    console.log(error);
                });
        } catch(error) {
            console.log(error);
        };
    });

    // Add a 'close' event handler to this instance of socket
    sock.on('close', function(data) {
        let index = sockets.findIndex(function(o) {
            return o.remoteAddress === sock.remoteAddress && o.remotePort === sock.remotePort;
        })
        if (index !== -1) sockets.splice(index, 1);
        console.log('CLOSED: ' + sock.remoteAddress + ' ' + sock.remotePort);
    });
});