JustPy应用部署在AWS Lightsail Ubuntu虚拟机上无报错但页面无法显示问题求助

First, let's confirm your code and JustPy env config look solid— setting HOST = '0.0.0.0' is exactly what you need to make the service accessible externally, and your hello-world app is a valid minimal test. The issue almost always boils down to network access restrictions, which are easy to fix. Here's the step-by-step breakdown:

1. Fix AWS Lightsail Firewall Rules (Most Likely Culprit) #

Lightsail blocks all incoming ports by default except for SSH (22), HTTP (80), and HTTPS (443). Your app is running on port 8000, which isn't allowed by default:

• Log into the AWS Lightsail console and select your Ubuntu instance
• Navigate to the Networking tab
• Scroll to the Firewall section and click Add rule
• Set the following values:
  • Protocol: TCP
  • Port range: 8000
  • Source: 0.0.0.0/0 (or restrict to your specific IP for extra security)
• Save the rule and wait 1-2 minutes for changes to take effect

2. Verify Ubuntu Local Firewall (UFW) #

Even if Lightsail's firewall is open, Ubuntu's built-in UFW might be blocking the port:

• SSH into your instance and run this to check UFW status:

  sudo ufw status
  

• If UFW is enabled and you don't see a rule allowing port 8000, add it with:

  sudo ufw allow 8000/tcp
  

• Recheck status to confirm the rule is active:

  sudo ufw status
  

3. Test Local Connectivity First #

Before testing externally, confirm the app is actually responding on the instance:

• Run this command on your Lightsail instance:

  curl http://localhost:8000
  

• If you get an HTML response (look for <h1>Hello World!</h1> in the output), the app is working correctly. If not:
  • Check if port 8000 is in use by another process:

    sudo lsof -i :8000
    

  • Reinstall JustPy if there's a corrupt installation:

    pip3 uninstall justpy -y && pip3 install justpy
    

4. Ensure You're Using the Correct External URL #

You mentioned having a static URL— make sure you're accessing the app with:

http://your-static-ip-or-domain:8000

• Don't use http://0.0.0.0:8000 externally; that's only the internal listen address for the server
• Don't forget the :8000 port suffix— browsers default to port 80/443, so omitting it will fail

5. Keep the App Running After SSH Disconnect (Optional) #

If you close your SSH session, the app will stop. To keep it running in the background:

• Use nohup to run it detached:

  nohup python3 run.py &
  

• Check logs later with:

  cat nohup.out
  

• For a more robust setup, create a systemd service to manage the app (auto-starts on reboot, easy to restart/stop)

内容的提问来源于stack exchange，提问作者Christian Walter