EC2上部署Rails：Puma有响应但浏览器页面始终无法加载

Hey there! Let’s work through this together — I’ve dealt with similar EC2/Rails connectivity headaches before, so here are the most common fixes to check:

1. Fix EC2 Security Group Port Access #

This is the #1 culprit for "server runs but browser can’t connect" scenarios. AWS blocks inbound traffic by default, so you need to open up the Rails development port (3000):

• Head to your AWS EC2 console, select your instance, and go to the Security Groups tab
• Edit inbound rules, add a new rule:
  • Type: Custom TCP
  • Port range: 3000
  • Source: Either 0.0.0.0/0 (for public access) or your specific IP address (more secure)
• Save the rules and try accessing your instance’s public IP:3000 again.

2. Bind Puma to All Network Interfaces #

By default, Rails starts Puma bound only to localhost (127.0.0.1), which means it’s only accessible from inside the EC2 instance, not your browser.

• Start your server with this command instead:

  rails s -b 0.0.0.0
  

This tells Puma to listen on all available network interfaces, making it reachable from outside the instance.

3. Verify Puma’s Status and Check Logs #

Let’s make sure Puma is actually running and not silently failing:

• Check for active Puma processes:

  ps aux | grep puma
  

• If it’s running, dig into the Rails development logs for errors:

  cat log/development.log
  

Look for red flags like database connection issues (even new projects can hit SQLite permission problems) or routing errors. Also, avoid running Puma in the background at first — keep it in your terminal to see real-time output.

4. Check Ubuntu’s UFW Firewall #

Ubuntu 16.04 comes with UFW enabled by default, which might be blocking port 3000:

• Check UFW’s current status:

  sudo ufw status
  

• If it’s active, allow port 3000:

  sudo ufw allow 3000
  sudo ufw reload
  

5. Confirm Listen Gem Compatibility #

You mentioned installing listen v3.1.5 — Rails 5.1.6 requires ~>3.1.0, so that version is compatible, but sometimes gem dependencies can get messed up:

• Reinstall your bundle to ensure all gems are properly set up:

  bundle install
  

Then restart your Rails server to apply any changes.

A quick note: If this were a production setup, you’d want to use Nginx as a reverse proxy with Puma, but for a test app, the above steps should get you up and running.

内容的提问来源于stack exchange，提问作者marcioneto