How to Debug a Remote Java Application Using Nginx Reverse Proxy

What are the steps to debug a remote Java application that is routed through an Nginx reverse proxy?

Debugging a remote Java application that utilizes an Nginx reverse proxy can introduce unique challenges, particularly with regards to network configurations and connection handling. This guide offers a systematic approach to set up your debugging environment effectively.

java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=*:5005 -jar your-application.jar

Causes

• Improper configuration of Nginx can prevent successful communication between the debugger and application.
• Firewall settings might block required ports used for remote debugging.
• Debugging options not enabled in the Java Virtual Machine (JVM).

Solutions

• Configure Nginx to properly forward headers and enable WebSocket connections if needed.
• Ensure that the firewall allows traffic on the debugging port (commonly 5005).
• Launch the Java application with the appropriate debug options, such as '-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=*:5005'.

Mistake: Not setting the correct value for the 'address' parameter during JVM launch.

Solution: Use 'address=*:5005' to accept connections from any host.

Mistake: Omitting necessary headers in Nginx configurations for forwarding requests.

Solution: Add 'proxy_set_header Host $host;' and similar directives to your Nginx config.

Mistake: Assuming Nginx handles all requests without explicit debugging rules.

Solution: Define specific Nginx locations or traffic types that require debugging.