Fastify Custom Healthcheck

fastify-custom-healthcheck is a plugin for creating a health route with custom evaluations.

Install

npm i fastify-custom-healthcheck

Usage

Require the module and just register it as any other fastify plugin. From fastify-custom-healthcheck on decorator is going to be added to your server for adding custom health checks.

const fastify = require('fastify')();
const customHealthCheck = require('fastify-custom-healthCheck');

fastify.register(customHealthCheck, options).then(() => {
    fastify.addHealthCheck('metric', () => {
        return new Promise((resolve) => setTimeout(resolve, 5000));
    });
});

fastify.listen(3000);

API

register plugin

fastify.register(customHealthCheck, {
    path: '/health/check', // default health
    info: {}, // custom information object
});

register options

• path: path where you can reach health check route.
  • default value: '/health'.
• info: object where you can define custom information you would like to include in healthcheck response object.
• exposeFailure: Flag that enables additional information to be presented in health check object when a check fails.
  • default value: false
• schema: If set to true, default schema is used for the route definition, if to false - no schema. If object is passed, it will be used as a schema. This can be used to enable support for custom type providers, e. g. zod or typebox.
  • default value: true

Decorator

After registering plugin you can use the decorator for adding custom health checks.

fastify.addHealthCheck(label, () => {}, { value: true });

decorator options

• value: If you add on addHealthCheck a value, when computing health check an equality check happens between evaluation and the value returned by the health check function. If the values are different health check fails.

Example response

{
  "healthChecks": {
    "mongo": {
      "status": "FAIL",
      "reason": "MongoNetworkError: failed to connect to server [localhost:27017] on first connect [Error: connect ECONNREFUSED 127.0.0.1:27017\n    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1144:16) {\n  name: 'MongoNetworkError'\n}]"
    },
    "kafka": "HEALTHY",
    "redis": "HEALTHY" 
  },
  "stats": {
    "creationTime": "2020-08-04T19:16:29.766Z",
    "uptime": 0.303361107,
    "memory": {
      "rss": 50102272,
      "heapTotal": 29270016,
      "heapUsed": 16499104,
      "external": 20754444,
      "arrayBuffers": 19273278
    }
  },
  "info": {
    "example": "Response",
  }
}

Acknowledgements

This module is inspired by server-health and the need of having this functionality in fastify.

Example

You can also check an example usage.

Issues

For any issues.

License

MIT License