Healthchecks Framework for KeystoneJS (or any Express app)

Enable the default healthchecks for Keystone by adding this package to your project and setting the following option:

keystone.set('healthchecks', true)

Or, you can define your own healthchecks and import them like this:

// this will import all javascript files in the ./healthchecks directory
keystone.set('healthchecks', keystone.import('healthchecks'));

For more control, you can create the healthcheck route handler and plug it into any express app or router by using the createRoute method, e.g

const checks = { MyHealthCheck }; // see below
app.use('/is-everything-ok', require('keystone-healthchecks').createRoute(checks));

Each healthcheck should export a Class that extends Healthcheck, e.g

const healthchecks = require('keystone-healthchecks');
const Healthcheck = healthchecks.Healthcheck;

module.exports = class MyHealthCheck extends Healthcheck {
	// optional, will default to the name of the Class
	get name () {
		return `My Health Check`;
	}
	// optional, defines a timeout for the check in ms
	get timeout () {
		return 500;
	}
	// required, must return a Promise or Promise.resolve for pass or
	// Promise.reject for fail. The argument passed to the resolve / reject
	// will be returned by the healthcheck endpoint, along with the status
	resolver () {
		return keepCalmAndCarryOn()
			.then(() => Promise.resolve('This is Fine'))
			.catch(() => Promise.reject('OMG THIS IS NOT OK'));
	}
};

There are several health checks of kinds often used in a keystone application provided, a List health check to check on a keystone model and ensure database connectivity, and a uri health check that can check a generic external dependency.

These both have a class that extends HealthCheck as well as a factory function to create them.

These can be required at:

const { healthchecks } = require('keystone-healthchecks');

This function takes in a keystone List object, and returns a health check that will perform a findOne operation on the list. You can set one up as follows:

const User = require('keystone').List('User');
const canQueryListFactory = require('keystone-healthchecks').healthchecks.canQueryListFactory

const check = canQueryListFactory(User);

This is a standard health check for an external uri which does not require any form of authorisation. It makes a http request to the endpoint, and treats a 200 response as a valid status, while treating all other responses as an error. It can be set up as follows.

It has one required parameters, a uri, and then two optional parameters, siteName and timeout.

If no siteName is provided, the check's name is defaulted to the uri. If no timeout is provided, the timeout is defaulted to 3 seconds.

const canQueryUriFactory = require('keystone-healthchecks').healthchecks.canQueryUriFactory.

const check = canQueryUriFactory('http://aplaceontheinternet.com'

MIT Licensed. Copyright (c) 2017 Thinkmill Pty Ltd