app1/node/app.js

const express = require('express');
const app = express();
const mongoose = require('mongoose');
const Schema = mongoose.Schema;
const database = 'mongodb://' + process.env.mongousr + ':' + process.env.mongopwd + '@mongo:27017/test';
const today = new Date();
var counter = 0;
const Prometheus = require('prom-client');
const fs = require('file-system');
const marked = require('marked');
const jwt = require('jsonwebtoken');

// database connection (with retries)
const options = {
  autoIndex: false, // Don't build indexes
  reconnectTries:30, // Retry up to 30 times
  reconnectInterval: 500, // Reconnect every 500ms
  poolSize: 10, // Maintain up to 10 socket connections
  // If not connected, return errors immediately rather than waiting for reconnect
  bufferMaxEntries: 0,
  useNewUrlParser: true
}

const connectWithRetry = () => {
  console.log('MongoDB connection with retry')
  mongoose.connect(database, options).then(()=>{
    console.log('MongoDB is connected')
  }).catch(err=>{
    console.log('MongoDB connection unsuccessful, retry after 5 seconds.')
    setTimeout(connectWithRetry, 5000)
  })
}

const libCounter = new Prometheus.Counter({
  name: 'lib_invocation_count',
  help: 'A simple counter for app access during runtime created with prometheus nodejs library'
});

const libUptime = new Prometheus.Counter({
  name: 'lib_upTime',
  help: 'uptime A counter of the application\'s uptime in seconds created with prometheus nodejs library.'
})

console.log('mongousr: ', process.env.mongousr);
console.log('mongopwd: ', process.env.mongopwd);

// Prometheus Default Metrics collector
const collectDefaultMetrics = Prometheus.collectDefaultMetrics;
// Probe every 5th second.
collectDefaultMetrics({ timeout: 5000 });

// new schema model object based on the structure of what I want to put on MongoDB collection
var testSchema = new Schema({
  color: {
    type: String
  }
},{
  collection: 'test'
});

// new object that will hold the data using model structure made above
var colors = mongoose.model('colorName', testSchema);

// Prometheus metrics endpoint - Library
app.get('/metrics', function(req, res){
  libUptime.inc(Math.floor(process.uptime()));
  res.set('Content-Type', Prometheus.register.contentType)
  res.end(Prometheus.register.metrics())
  libUptime.reset();
});

// Prometheus metrics endpoint - Handmade
app.get('/metrics2', function(req, res){
  var now = new Date();
  var passedTime = now - today;
  res.writeHead(200, {'Content-Type':'text/plain'});
  res.write('# HELP uptime A counter of the application\'s uptime in millisenconds.' + '\n');
  res.write('# TYPE uptime counter' + '\n');
  res.write('uptime ' + passedTime + '\n');
  res.write('# HELP invocation_count A simple counter for app access during runtime' + '\n');
  res.write('# TYPE invocation_count counter'+ '\n');
  res.write('invocation_count ' + counter + '\n');
  res.end();
})

// JWT generation
app.use(express.json());
app.post('/token', function(req, res){
  console.log(req.body);
  console.log(req.body.username);
  console.log(req.body.password);
  if (req.body.username=='user1') {
    if (req.body.password=='pass1') {
      var token = jwt.sign(req.body, 'wowmuchsecretveryhiddenwow');
      console.log(token);
      // res.json(token);
      res.status(200).json({
        success: 'SUCCESS! You\'re in.',
        token: token
      });
    } else {
      res.status(500).send('this is not the password I expected');
    }
  } else {
    res.status(500).send('this is not the user I want');;
  }
});

// Default message for testing
app.get('/', (req, res)=>{
  res.json([{message:'yes, your nodejs app is really running'}]);
  counter++; // for prometheus invocation_count metric
  libCounter.inc(); // for prometheus lib_invocation_count metric
});

// Test endpoint for md files rendering
app.get('/test', function(req, res) {
  var path = '/app/README.md';
  var file = fs.readFileSync(path, 'utf8');
  res.send(marked(file.toString()));
});


// Mongo query
app.get('/info', function(req, res){
  colors.find({}).then(function (colors) {
    res.json(colors);
  });
});


// Mongo insert
app.post('/info/add/:name', function(req, res){
  var item = {color: req.params.name};
  var data = new colors(item);
  data.save();
  res.send('color ' + req.params.name + ' added to database');
});

// connectWithRetry();

app.listen(3001, () => {
  console.log('Server running on port 3001');
  console.log('process.env.PORT: ' + process.env.PORT);
});