Skip to main content Set up comprehensive observability for Replit integrations with metrics, traces, and alerts.
Use when implementing monitoring for Replit operations, setting up dashboards,
or configuring alerting for Replit integration health.
Trigger with phrases like "replit monitoring", "replit metrics",
"replit observability", "monitor replit", "replit alerts", "replit tracing".
npx skills add jeremylongshore/claude-code-plugins-plus-skills --skill replit-observability ai automation claude-code devops mcp ai-agents
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
// 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 = 'degraded';
}
}
// Memory metrics
const mem = process.memoryUsage();
checks.memory = {
heapMB: Math.round(mem.heapUsed / 1024 / 1024),
totalMB: Math.round(mem.heapTotal / 1024 / 1024),
rssMB: Math.round(mem.rss / 1024 / 1024),
percent: ((mem.heapUsed / mem.heapTotal) * 100).toFixed(1),
};
// Node.js info
checks.runtime = {
node: process.version,
platform: process.platform,
pid: process.pid,
};
res.status(checks.status === 'ok' ? 200 : 503).json(checks);
});
// Lightweight ping for uptime monitors
router.get('/ping', (req, res) => res.send('pong'));
export default router;
Step 2: Structured Logging // src/utils/logger.ts — structured JSON logging
const IS_PROD = process.env.NODE_ENV === 'production';
type LogLevel = 'debug' | 'info' | 'warn' | 'error';
function log(level: LogLevel, message: string, data?: Record<string, any>) {
if (level === 'debug' && IS_PROD) return;
const entry = {
timestamp: new Date().toISOString(),
level,
message,
repl: process.env.REPL_SLUG,
...data,
};
// JSON format for machine parsing, human-readable in dev
if (IS_PROD) {
consolelevel === 'error' ? 'error' : 'log');
} else {
consolelevel === 'error' ? 'error' : 'log'}] ${message}`,
data || ''
);
}
}
export const logger = {
debug: (msg: string, data?: any) => log('debug', msg, data),
info: (msg: string, data?: any) => log('info', msg, data),
warn: (msg: string, data?: any) => log('warn', msg, data),
error: (msg: string, data?: any) => log('error', msg, data),
};
// Request logging middleware
export function requestLogger(req: any, res: any, next: any) {
const start = Date.now();
res.on('finish', () => {
logger.info('request', {
method: req.method,
path: req.path,
status: res.statusCode,
durationMs: Date.now() - start,
userId: req.headers['x-replit-user-id'] || 'anonymous',
});
});
next();
}
Step 3: External Uptime Monitoring Set up external monitors to detect Autoscale cold starts and outages:
UptimeRobot (free tier: 50 monitors):
1. Create new monitor: HTTP(s)
2. URL: https://your-app.replit.app/ping
3. Interval: 5 minutes
4. Alert contacts: email, Slack webhook
Better Stack / Datadog / Grafana Cloud:
- Same setup, more features
- Track response time trends
- Detect cold start patterns
- Set up PagerDuty integration
Key metrics to monitor externally:
- Uptime percentage (target: 99.9%)
- Response time P95 (target: < 2s)
- Cold start frequency (Autoscale only)
- SSL certificate expiry
Step 4: Cold Start Detection // Track cold starts for Autoscale deployments
const COLD_START_THRESHOLD_MS = 5000;
let firstRequestTime: number | null = null;
app.use((req, res, next) => {
if (!firstRequestTime) {
firstRequestTime = Date.now();
const bootTime = process.uptime();
if (bootTime < 30) { // Just started
logger.info('cold_start_detected', {
bootTimeMs: Math.round(bootTime * 1000),
path: req.path,
});
}
}
next();
});
Step 5: Alerting Rules // src/utils/alerts.ts — send alerts to Slack on issues
async function alertSlack(message: string, severity: 'info' | 'warning' | 'critical') {
const webhookUrl = process.env.SLACK_WEBHOOK_URL;
if (!webhookUrl) return;
const emoji = { info: 'information_source', warning: 'warning', critical: 'rotating_light' };
await fetch(webhookUrl, {
method: 'POST',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({
text: `:${emoji[severity]}: [${severity.toUpperCase()}] ${process.env.REPL_SLUG}\n${message}`,
}),
});
}
// Monitor memory usage
setInterval(async () => {
const mem = process.memoryUsage();
const heapPercent = (mem.heapUsed / mem.heapTotal) * 100;
if (heapPercent > 90) {
await alertSlack(`Memory critical: ${heapPercent.toFixed(1)}% heap used`, 'critical');
} else if (heapPercent > 75) {
await alertSlack(`Memory warning: ${heapPercent.toFixed(1)}% heap used`, 'warning');
}
}, 60000);
// Monitor error rate
let errorCount = 0;
let requestCount = 0;
app.use((req, res, next) => {
requestCount++;
res.on('finish', () => {
if (res.statusCode >= 500) errorCount++;
});
next();
});
setInterval(async () => {
if (requestCount > 0) {
const errorRate = (errorCount / requestCount) * 100;
if (errorRate > 5) {
await alertSlack(`Error rate: ${errorRate.toFixed(1)}% (${errorCount}/${requestCount})`, 'critical');
}
}
errorCount = 0;
requestCount = 0;
}, 300000); // Check every 5 minutes
Step 6: Replit Dashboard Monitoring Built-in monitoring in Replit:
1. Deployment Settings > Logs: real-time stdout/stderr
2. Deployment Settings > History: deploy timeline + rollbacks
3. Database pane > Settings: storage usage + connection info
4. Billing > Usage: compute, egress, and storage costs
Check deployment logs:
- Click on active deployment
- View real-time log stream
- Filter by error/warning
- Logs persist across container restarts
Error Handling Issue Cause Solution Cold starts undetected No external monitor Set up UptimeRobot or similar Deployment logs missing Container restarted Use external log aggregator Memory leak unnoticed No memory monitoring Add heap tracking + alerts DB pool exhaustion Too many connections Monitor pool.totalCount in health
Resources
Next Steps For incident response, see replit-incident-runbook.
Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
Set up and use 1Password CLI (op). Use when installing the CLI, enabling desktop app integration, signing in (single or multi-account), or reading/injecting/running secrets via op.
CLI to manage emails via IMAP/SMTP. Use `himalaya` to list, read, write, reply, forward, search, and organize emails from the terminal. Supports multiple accounts and message composition with MML (MIME Meta Language).
Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
Set up and use 1Password CLI (op). Use when installing the CLI, enabling desktop app integration, signing in (single or multi-account), or reading/injecting/running secrets via op.
CLI to manage emails via IMAP/SMTP. Use `himalaya` to list, read, write, reply, forward, search, and organize emails from the terminal. Supports multiple accounts and message composition with MML (MIME Meta Language).
