replit-observability

# Replit Observability ## Overview Monitor Replit deployment health, track cold starts, measure resource usage, and set up alerting. Covers Replit's built-in monitoring, external health checking, structured logging, and integration with monitoring services. ## Prerequisites - Replit app deployed (Autoscale or Reserved VM) - Health endpoint implemented (`/health`) - External monitoring service (UptimeRobot, Better Stack, or Prometheus) ## Instructions ### Step 1: Health Endpoint with Detailed Metrics ```typescript // src/routes/health.ts — comprehensive health check import { Router } from 'express'; import { pool } from '../services/postgres'; const router = Router(); const startTime = Date.now(); router.get('/health', async (req, res) => { const checks: Record<string, any> = { status: 'ok', uptime: process.uptime(), bootTime: ((Date.now() - startTime) / 1000).toFixed(1) + 's ago', timestamp: new Date().toISOString(), repl: process.env.REPL_SLUG, region: process.env.REPLIT_DEPLOYMENT_REGION, env: process.env.NODE_ENV, }; // Database check if (process.env.DATABASE_URL) { const dbStart = Date.now(); try { await pool.query('SELECT 1'); checks.database = { status: 'connected', latencyMs: Date.now() - dbStart, pool: { total: pool.totalCount, idle: pool.idleCount }, }; } catch (err: any) { checks.database = { status: 'disconnected', error: err.message }; checks.status = 'degr...