Express Health Check Middleware

Add health, readiness, liveness and metrics functionality to express.

Features

• Add Health Endpoint

  GET /-/health

  Only checks whether the application server is running It does not verify the database or other services are running. A successful response will return a 200 status code

• Add Readiness Endpoint

  GET /-/readiness

  Sometimes, applications are temporarily unable to serve traffic. For example, an application might need to load large data or configuration files during startup, or depend on external services after startup. In such cases, you don’t want to kill the application, but you don’t want to send it requests either.

• Add Liveness Endpoint

  GET /-/liveness

  Many applications running for long periods of time eventually transition to broken states, and cannot recover except by being restarted.

• Add Metrics Endpoint

  GET /-/metrics

  • Node process metrics
  • Infrastructure to collect internal metrics (like southbound APIs)
  • API to retrieve the collected metrics and to reset them.

How to use

npm install --save @crdtech/express-health-check-middleware

const express = require('express');

const healthCheckMiddleware = require('@crdtech/express-health-check-middleware');
const mongoose = require('mongoose');

const app = express();

app.use(healthCheckMiddleware({
  checkFunctions: {
    // Example add check mongo connection
    mongo: async()=>{
      let result = await mongoose.connection.db.admin().ping()
      return result
    },
    // You can add your own check function
    // <key> : <async|return Promise>
  },

  // Optional, This is default settings
  authMiddleware: (req, res, next) => {
    if (process.env.HEALTH_CHECK_ACCESS_TOKEN) {
      if (req.query.token !== process.env.HEALTH_CHECK_ACCESS_TOKEN) {
        return res.status(404).send('');
      }
    }
    next();
  },

  // Optional, This is default settings
  routes: {
    health   : '/~/health',
    readiness: '/~/readiness',
    liveness : '/~/liveness',
    metrics  : '/~/metrics',
  },
})(app));

app.get('/', function(req, res) {
  res.json({hello: 'world'});
});

const main = async()=>{
  let mongooseOptions = { useNewUrlParser: true }
  let databaseUrl = process.env.DATABASE_URL || 'mongodb://localhost:27017/my-app'
  await mongoose.connect(databaseUrl, mongooseOptions)
  app.listen(3000);
}

main();