health-check-endpoints

SKILL.md

Health Check Endpoints

Table of Contents

Overview

When to Use

Quick Start

Reference Guides

Best Practices

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

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