Health Check Endpoints
Table of Contents
Overview
Implement health check endpoints to monitor service health, dependencies, and readiness for traffic.
When to Use
- Kubernetes liveness and readiness probes
- Load balancer health checks
- Service discovery and registration
- Monitoring and alerting systems
- Circuit breaker decisions
- Auto-scaling triggers
- Deployment verification
Quick Start
Minimal working example:
import express from "express";
import { Pool } from "pg";
import Redis from "ioredis";
interface HealthStatus {
status: "healthy" | "degraded" | "unhealthy";
timestamp: string;
uptime: number;
checks: Record<string, CheckResult>;
version?: string;
environment?: string;
}
interface CheckResult {
status: "pass" | "fail" | "warn";
time: number;
output?: string;
error?: string;
}
class HealthCheckService {
private startTime = Date.now();
private version = process.env.APP_VERSION || "1.0.0";
private environment = process.env.NODE_ENV || "development";
// ... (see reference guides for full implementation)Reference Guides
Detailed implementations in the references/ directory:
| Guide | Contents |
|---|---|
| Express.js Health Checks | Express.js Health Checks |
| Spring Boot Actuator-Style (Java) | Spring Boot Actuator-Style (Java) |
| Python Flask Health Checks | Python Flask Health Checks |
Best Practices
✅ DO
- Implement separate liveness and readiness probes
- Keep liveness probes lightweight
- Check critical dependencies in readiness
- Return appropriate HTTP status codes
- Include response time metrics
- Set reasonable timeouts
- Cache health check results briefly
- Include version and environment info
- Monitor health check failures
❌ DON'T
- Make liveness probes check dependencies
- Return 200 for failed health checks
- Take too long to respond
- Skip important dependency checks
- Expose sensitive information
- Ignore health check failures