Using PM2 cron-start for Recurring Tasks Server-Level Scheduling

Using PM2 cron-start for Recurring Tasks

PM2 has built-in cron support that runs Node.js scripts at scheduled intervals. This is a server-level alternative to node-cron.

Why Use PM2 cron?

1. Server-level Runs even if your main app is down
2. PM2 managed Automatic restart on failure
3. No extra dependencies Built into PM2
4. Logs PM2 captures all output
5. Simple No code changes needed

PM2 cron-start Syntax

# Run a script every day at midnight
pm2 start scripts/cleanup.js --cron "0 0 * * *" --name daily-cleanup

# Run every hour
pm2 start scripts/stats.js --cron "0 * * * *" --name hourly-stats

# Run every 15 minutes
pm2 start scripts/health-check.js --cron "*/15 * * * *" --name health-check

PM2 Ecosystem File

// ecosystem.config.js
module.exports = {
  apps: [
    // Main API server
    {
      name: "devtinder-api",
      script: "src/server.js",
      instances: "max",
      exec_mode: "cluster"
    },
    
    // Cron jobs
    {
      name: "daily-cleanup",
      script: "scripts/cleanup.js",
      cron: "0 0 * * *",
      autorestart: false  // Don't restart after completion
    },
    {
      name: "hourly-stats",
      script: "scripts/stats.js",
      cron: "0 * * * *",
      autorestart: false
    },
    {
      name: "weekly-report",
      script: "scripts/weeklyReport.js",
      cron: "0 0 * * 1",  // Every Monday at midnight
      autorestart: false
    }
  ]
};

pm2 start ecosystem.config.js
pm2 save

Creating Cron Scripts

// scripts/cleanup.js
require("dotenv").config();
const mongoose = require("mongoose");
const User = require("../src/models/User");

const run = async () => {
  try {
    await mongoose.connect(process.env.MONGODB_URI);
    console.log("Connected to MongoDB");
    
    // Delete expired tokens
    const result = await User.updateMany(
      { resetPasswordExpires: { $lt: new Date() } },
      { $unset: { resetPasswordToken: 1, resetPasswordExpires: 1 } }
    );
    console.log(`Cleaned up ${result.modifiedCount} users`);
    
    await mongoose.disconnect();
    console.log("Done");
    process.exit(0);
  } catch (err) {
    console.error("Cleanup failed:", err);
    process.exit(1);
  }
};

run();

PM2 cron vs node-cron

When to Use PM2 cron vs node-cron

Use PM2 cron for:

• Database backups (independent of app)
• Log rotation (server-level)
• System health checks
• Report generation (doesn't need app context)

Use node-cron for:

• Tasks that need app state (cache, connections)
• Tasks that use app models and utilities
• Tasks that should stop when the app stops
• Tasks that need the same database connection

Viewing PM2 Cron Jobs

# List all PM2 processes
pm2 status

# View logs of a specific cron job
pm2 logs daily-cleanup

# View logs of all cron jobs
pm2 logs

# Stop a cron job
pm2 stop daily-cleanup

# Restart a cron job
pm2 restart daily-cleanup

# Delete a cron job
pm2 delete daily-cleanup

The Takeaway

PM2 cron-start runs Node.js scripts at scheduled intervals at the server level. Use it for independent tasks like backups, log rotation, and system health checks. Use node-cron for tasks integrated with your app (using models, cache, connections). Both use cron expressions. PM2 cron jobs are managed by PM2 (automatic restart, logs, monitoring) and run in separate processes.