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Health checks

The gateway service determines if a node still can be used safely by frequently checking its health. Health checks are used for health determination. Jitar has no out-of-the-box health checks, but you can create and add your own. A common use case is for checking database availability. In case a node can't access its database, we want the gateway to stop using it. Health checks can be added to any of the services.

Creating health checks

Jitar provides an interface you have to implement in order to add a custom check to a service. Let's look at a simple database check example:

// src/health/DatabaseHealthCheck.ts
import { HealthCheck } from 'jitar';
import { pingDatabase } from '../common/utils;

export default class DatabaseHealthCheck implements HealthCheck
    async isHealthy(): Promise<boolean>
        return pingDatabase();

To prevent the health checks from blocking the monitoring, each health check should be non-blocking and cannot throw an error yet.

Adding health checks

A health check needs to be added to the service that has the connection to the database. For this we need to create a custom starter, just like we do for adding middleware.

// node.ts
import { startServer } from 'jitar';

import DatabaseHealthCheck from './health/DatabaseHealthCheck.js';

const moduleImporter = async (specifier: string) => import(specifier);

const server = await startServer(moduleImporter);
server.addHealthCheck('database', new DatabaseHealthCheck());

Once added, the gateway will trigger the check automatically. You can also check yourself using the health API. More information on this can be found in the MONITOR section.

Jitar is a project by Masking Technology