aula-15: implementação completa APM (Tempo + OTel + demo app)
Componentes: - tempo-values.yaml: Grafana Tempo monolithic, 256Mi, 10Gi PVC - otel-collector-values.yaml: recebe OTLP, exporta traces→Tempo, gera span metrics (RED)→Victoria Metrics via spanmetrics connector - demo-app/: Node.js com rotas /fast (1 query), /slow (N+1, 51 queries), /fixed (JOIN), auto-instrumentado com OpenTelemetry - alerts/latency-alerts.yaml: VMRule com Doherty threshold (p95>400ms) - setup.sh: instala Tempo, OTel Collector, configura Grafana datasource, deploy demo app via ConfigMap (sem Docker build necessário) - cleanup.sh: remove apenas recursos da aula-15, preserva aula-12 Zero hardcoded hostnames. Tudo via .env e placeholders.
This commit is contained in:
ArgoCD Setup
230
aula-15/demo-app/app.js
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230
aula-15/demo-app/app.js
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'use strict';
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const express = require('express');
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const { Pool } = require('pg');
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const app = express();
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const PORT = process.env.PORT || 3000;
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const pool = new Pool({
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host: process.env.PG_HOST || 'localhost',
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port: parseInt(process.env.PG_PORT || '5432', 10),
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user: process.env.PG_USER || 'demo',
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password: process.env.PG_PASSWORD || 'demo',
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database: process.env.PG_DATABASE || 'demo',
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});
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// --- Database seeding ---
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async function seedDatabase() {
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const client = await pool.connect();
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try {
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const tableCheck = await client.query(`
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SELECT EXISTS (
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SELECT FROM information_schema.tables WHERE table_name = 'users'
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)
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`);
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if (tableCheck.rows[0].exists) {
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const countResult = await client.query('SELECT COUNT(*) FROM users');
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if (parseInt(countResult.rows[0].count, 10) > 0) {
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console.log('Database already seeded, skipping.');
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return;
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}
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}
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console.log('Seeding database...');
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await client.query(`
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CREATE TABLE IF NOT EXISTS users (
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id SERIAL PRIMARY KEY,
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name VARCHAR(100) NOT NULL,
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email VARCHAR(150) NOT NULL,
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created_at TIMESTAMP DEFAULT NOW()
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)
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`);
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await client.query(`
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CREATE TABLE IF NOT EXISTS posts (
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id SERIAL PRIMARY KEY,
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user_id INTEGER REFERENCES users(id),
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title VARCHAR(200) NOT NULL,
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body TEXT NOT NULL,
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created_at TIMESTAMP DEFAULT NOW()
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)
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`);
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// Insert 50 users
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for (let i = 1; i <= 50; i++) {
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await client.query(
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'INSERT INTO users (name, email) VALUES ($1, $2)',
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[`User ${i}`, `user${i}@example.com`]
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);
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}
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// Insert 10 posts per user (500 posts total)
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for (let userId = 1; userId <= 50; userId++) {
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for (let p = 1; p <= 10; p++) {
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await client.query(
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'INSERT INTO posts (user_id, title, body) VALUES ($1, $2, $3)',
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[userId, `Post ${p} by User ${userId}`, `Content of post ${p} by user ${userId}. Lorem ipsum dolor sit amet.`]
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);
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}
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}
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console.log('Database seeded: 50 users, 500 posts.');
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} finally {
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client.release();
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}
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}
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// --- Routes ---
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app.get('/health', (_req, res) => {
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res.json({ status: 'ok' });
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});
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// Fast route: single query, returns 10 users
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app.get('/fast', async (_req, res) => {
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const start = Date.now();
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try {
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const result = await pool.query('SELECT * FROM users LIMIT 10');
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const duration = Date.now() - start;
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res.json({
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route: '/fast',
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description: 'Single query - SELECT users LIMIT 10',
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query_count: 1,
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duration_ms: duration,
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data: result.rows,
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});
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} catch (err) {
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res.status(500).json({ error: err.message });
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}
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});
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// Slow route: N+1 query pattern
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app.get('/slow', async (_req, res) => {
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const start = Date.now();
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try {
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const usersResult = await pool.query('SELECT * FROM users');
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const users = usersResult.rows;
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let queryCount = 1;
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const usersWithPosts = [];
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for (const user of users) {
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const postsResult = await pool.query(
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'SELECT * FROM posts WHERE user_id = $1',
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[user.id]
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);
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queryCount++;
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usersWithPosts.push({
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...user,
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posts: postsResult.rows,
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});
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}
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const duration = Date.now() - start;
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res.json({
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route: '/slow',
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description: 'N+1 pattern - 1 query for users + 1 query per user for posts',
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query_count: queryCount,
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user_count: users.length,
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total_posts: usersWithPosts.reduce((sum, u) => sum + u.posts.length, 0),
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duration_ms: duration,
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data: usersWithPosts,
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});
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} catch (err) {
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res.status(500).json({ error: err.message });
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}
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});
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// Fixed route: single JOIN query
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app.get('/fixed', async (_req, res) => {
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const start = Date.now();
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try {
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const result = await pool.query(`
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SELECT
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u.id AS user_id,
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u.name,
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u.email,
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u.created_at AS user_created_at,
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p.id AS post_id,
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p.title,
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p.body,
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p.created_at AS post_created_at
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FROM users u
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LEFT JOIN posts p ON p.user_id = u.id
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ORDER BY u.id, p.id
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`);
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// Group results by user
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const usersMap = new Map();
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for (const row of result.rows) {
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if (!usersMap.has(row.user_id)) {
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usersMap.set(row.user_id, {
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id: row.user_id,
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name: row.name,
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email: row.email,
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created_at: row.user_created_at,
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posts: [],
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});
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}
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if (row.post_id) {
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usersMap.get(row.user_id).posts.push({
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id: row.post_id,
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title: row.title,
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body: row.body,
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created_at: row.post_created_at,
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});
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}
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}
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const usersWithPosts = Array.from(usersMap.values());
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const duration = Date.now() - start;
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res.json({
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route: '/fixed',
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description: 'Single JOIN query - the correct way',
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query_count: 1,
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user_count: usersWithPosts.length,
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total_posts: usersWithPosts.reduce((sum, u) => sum + u.posts.length, 0),
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duration_ms: duration,
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data: usersWithPosts,
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});
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} catch (err) {
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res.status(500).json({ error: err.message });
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}
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});
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// --- Startup ---
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async function main() {
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// Wait for PostgreSQL to be ready (with retries)
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let retries = 10;
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while (retries > 0) {
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try {
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await pool.query('SELECT 1');
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console.log('Connected to PostgreSQL.');
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break;
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} catch (err) {
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retries--;
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if (retries === 0) {
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console.error('Failed to connect to PostgreSQL after retries:', err.message);
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process.exit(1);
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}
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console.log(`Waiting for PostgreSQL... (${retries} retries left)`);
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await new Promise((resolve) => setTimeout(resolve, 3000));
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}
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}
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await seedDatabase();
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app.listen(PORT, () => {
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console.log(`Demo app listening on port ${PORT}`);
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});
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}
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main().catch((err) => {
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console.error('Fatal error:', err);
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process.exit(1);
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});
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