Changes yash

.eslintrc

@@ -0,0 +1,11 @@
+{
+  "extends": "airbnb-base",
+  "rules": {
+    "no-await-in-loop": 0,
+    "one-var": 0,
+    "max-len": ["error", { "code": 250 }],
+    "import/no-extraneous-dependencies": 1,
+    "no-underscore-dangle": [2, { "allow": ["_id"]} ],
+    "indent": ["error", 2]
+  }
+}

README.md

@@ -14,16 +14,35 @@ All you need to be aware of are the methods of this SDK and all the methods retu
 # Sample Usage -
 
 ```
-var mongoUtils = require('mongodb-nodejs-sdk');
-
-var doSomethingWithTheSetOfDocuments = function doSomethingWithTheSetOfDocuments(){
-    return mongoUtils.findDocumentsBasedOnQuery('mongoCollectionName', {status: "done"}, 0, {_id: 0})
-        .then(function(documents){
-            console.log(`Documents found in collection mongoCollectionName`, documents.length); 
-            return Promise.resolve(documents); //Do anything with the set of returned documents.
-        })
-        .catch(function(error){
-            return Promise.reject(error);
-        });
-};
+
+const mongoUtils = require('./utils');
+
+mongoUtils.initialize(DB_URL).then(async (resp) => {
+  console.log('connected', resp);
+  const resp = await mongoUtils.insertIntoDb('testCollection', ['asds','dasdsa','dasds']);
+});
+
 ```
+
+
+const PromClient = require('./prometheus');
+
+
+await PromClient.initialize({ job: 'jobName', instance: myIP() });
+PromClient.expressMiddleware(app);
+PromClient.serveExpressMetrics(app);
+
+
+const counter = PromClient.getCounter({ name: 'nodejs_product_service', help: 'metric_help', labelNames: ['status', 'state'] });
+counter.inc({ status: 'retry', state: '0' });
+counter.inc({ status: 'fail', state: '0' });
+
+
+const histogram = PromClient.getHistogram({
+    name: 'nodejs_http_request_duration_seconds',
+    help: 'metric_help',
+    labelNames: ['route'],
+    buckets,
+  });
+const end = histogram.startTimer();
+end({ route, method });

package.json

@@ -15,6 +15,12 @@
     "bluebird": "3.5.0",
     "documentation": "6.3.0",
     "lodash": "4.17.4",
-    "mongodb": "2.2.29"
+    "mongodb": "2.2.29",
+    "prom-client": "11.2.1"
+  },
+  "devDependencies": {
+    "eslint": "^3.14.1",
+    "eslint-config-airbnb": "^14.0.0",
+    "eslint-plugin-import": "^2.2.0"
   }
 }

prometheus.js

@@ -0,0 +1,106 @@
+const client = require('prom-client');
+const _ = require('lodash');
+
+
+class PromClient {
+
+  /**
+   * Method to initialize prometheus
+   * @param {string} defaultLabels Dictionary with key representing label name and value the label value. This will be appended to all the metrics
+   * @returns {object} Prometheus client object (does not need to be used though)
+   */
+  static initialize(defaultLabels) {
+    // This needs to be initialized only after Log
+    //check if log library is initialised
+    // console.log()
+    if (PromClient.client) return PromClient.client;
+    const registry = new client.Registry();
+    registry.setDefaultLabels(defaultLabels);
+
+    client.collectDefaultMetrics({ register: registry });
+    PromClient.client = registry;
+
+    PromClient.collectPromiseRejections();
+    return PromClient.client;
+  }
+
+  /**
+   * Method to create event listeners to record promise rejections for the whole service
+   */
+  static collectPromiseRejections() {
+    process.on('unhandledRejection', (reason) => {
+      const counter = PromClient.getCounter({ name: 'nodejs_promise_unhandled_rejection_count', help: 'metric_help' });
+      counter.inc();
+    });
+
+    process.on('rejectionHandled', () => {
+      const counter = PromClient.getCounter({ name: 'nodejs_promise_handled_rejection_count', help: 'metric_help' });
+      counter.inc();
+    });
+  }
+
+  /**
+   * Method to serve metrics collected
+   * @param {object} app app object
+   * @param {string} url if you want the exposed url to be something other than default metrics
+   * @returns {null}
+   */
+  static serveExpressMetrics(app, url) {
+    if (!PromClient.client) throw new Error('PromClient not initialized');
+    if (_.isNil(url)) app.get('/metrics', (req, res) => res.end(PromClient.client.metrics()));
+    else app.get(url, (req, res) => res.end(PromClient.client.metrics()));
+  }
+
+  /**
+   * Method to create histograms to record time taken to serve all URL's
+   * @param {object} app app object
+   * @param {array} bkts time buckets to be created for the histogram
+   * @returns {null}
+   */
+  static expressMiddleware(app, bkts) {
+    // Register this before paths
+    if (!PromClient.client) throw new Error('PromClient not initialized');
+    const buckets = !_.isNil(bkts) ? bkts : [0.01, 0.1, 0.2, 0.3, 0.4, 0.5, 1, 5, 10, 60, 120];
+    app.use((req, res, next) => {
+      const histogram = PromClient.getHistogram({
+        name: 'nodejs_http_request_duration_seconds',
+        help: 'metric_help',
+        labelNames: ['route'],
+        buckets,
+      });
+      const end = histogram.startTimer();
+      const route = req.path;
+      const { method } = req;
+      res.on('header', () => {
+        end({ route, method });
+      });
+      next();
+    });
+  }
+
+  static getCounter(config) {
+    if (!config || !config.name) throw new Error('Invalid arguments');
+    if (!PromClient.client) throw new Error('PromClient not initialized');
+    let counter = PromClient.client.getSingleMetric(config.name);
+    if (!counter) {
+      const newConfig = _.cloneDeep(config);
+      newConfig.registers = [PromClient.client];
+      counter = new client.Counter(newConfig);
+    }
+    return counter;
+  }
+
+  static getHistogram(config) {
+    if (!config || !config.name) throw new Error('Invalid arguments');
+    if (!PromClient.client) throw new Error('PromClient not initialized');
+    let histogram = PromClient.client.getSingleMetric(config.name);
+    if (!histogram) {
+      const newConfig = _.cloneDeep(config);
+      newConfig.registers = [PromClient.client];
+      histogram = new client.Histogram(newConfig);
+    }
+    return histogram;
+  }
+}
+
+module.exports = PromClient;