🔀 Leader Election Challenge

🧠 Scenario

You're running multiple instances of a Node.js app. Only ONE instance should actively perform a recurring background task — polling a 3rd-party API every 5 seconds.

If the leader goes down, another instance must take over within 5 seconds. Redis will be used to coordinate this.

✅ Your Task

• Implement leader election using Redis.
• Only the leader should perform the polling task.
• Automatically fail over if the leader dies.
• Implement /status endpoint to show:
  • Whether this instance is leader
  • When it last polled the API

🧪 Simulating Multiple Instances

PORT=3000 npm start
PORT=3001 npm start

Watch the logs to see leadership change and polling activity.

📦 Commands

npm install
npm start

📁 Project Structure

• src/index.js - App entrypoint
• src/lib/leader.js - Leader election logic (you implement)
• src/tasks/poll.js - Task runner logic (only leader runs it)
• src/routes/status.js - Status endpoint

🛠 Assumptions

• You can mock the 3rd-party API with console.log
• Do not use a DB — everything should work with Redis and in-memory state
• Use ioredis or redlock if you prefer (both supported)

Good luck!