Health check endpoint exists, returns HTTP 200, verifies critical dependencies, and consumed by load balancer

A health check endpoint that only returns HTTP 200 without verifying the database or downstream services will report healthy during a database connection pool exhaustion or broken third-party integration — exactly the conditions that cause user-facing failures. NIST SI-6 requires software verification; ISO 25010 reliability.availability requires accurate system state reporting. A load balancer routing traffic to a broken instance that reports itself healthy multiplies the failure, not the resilience. The health endpoint is the contract between your application and its infrastructure.

Create an /api/health route that verifies your critical dependencies before returning 200.

// src/app/api/health/route.ts
import { NextResponse } from 'next/server';
import { createClient } from '@/lib/supabase/server';

export async function GET() {
  try {
    const supabase = createClient();
    await supabase.from('_health').select('1').single(); // lightweight DB probe
    return NextResponse.json({ status: 'healthy' }, { status: 200 });
  } catch (err) {
    return NextResponse.json(
      { status: 'unhealthy', error: (err as Error).message },
      { status: 503 }
    );
  }
}

Then configure your platform to use it:

• AWS ALB: Target Group → Health check path: /api/health
• Kubernetes: livenessProbe.httpGet.path: /api/health
• Vercel: no native load balancer health check, but use Uptime Robot against this endpoint