IntelliJ IDEA's Built-in Remote Debugging | Generated by AI
To connect IntelliJ IDEA to the debug port of a WebSphere Liberty Server that you’ve started with server debug default, without using the WebSphere Liberty plugin, you can leverage IntelliJ IDEA’s built-in remote debugging feature. This approach works because WebSphere Liberty, when started in debug mode, exposes a debug port (typically 7777 by default) that any JVM debugger, including IntelliJ IDEA, can attach to. Below are the detailed steps to achieve this:
Step 1: Start the WebSphere Liberty Server in Debug Mode
When you run server debug default (assuming “default” is the name of your server; replace it with your actual server name if different), WebSphere Liberty starts with debugging enabled. By default, this command configures the server to listen for debug connections on port 7777.
- Command:
server debug default - What it does: This starts the “default” server in debug mode, automatically enabling JVM debugging options (e.g.,
-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=7777). - Verification: After running the command, check the server console output or logs (e.g.,
messages.log) to confirm that the server is listening on the debug port. Look for a message indicating the debug port (usually 7777 unless it’s overridden or unavailable).
Step 2: Confirm the Debug Port
The default debug port for WebSphere Liberty is 7777. However, if this port is in use or has been customized:
- Check the console output after starting the server. It might say something like “Listening for debugger connections on port 7777.”
- If the port differs (e.g., a random port is assigned due to a conflict), note the actual port number for use in IntelliJ IDEA.
For this guide, we’ll assume the default port 7777 unless your setup indicates otherwise.
Step 3: Configure Remote Debugging in IntelliJ IDEA
IntelliJ IDEA’s remote debugging feature allows you to connect to the server’s JVM without needing a specific WebSphere plugin. Here’s how to set it up:
- Open Run/Debug Configurations:
- In IntelliJ IDEA, go to the top menu and select Run > Edit Configurations.
- Add a New Remote Debug Configuration:
- Click the + button (or “Add New Configuration”) in the top-left corner.
- From the list, select Remote JVM Debug (it might just say “Remote” depending on your IntelliJ version).
- Set Configuration Details:
- Name: Give it a meaningful name, e.g., “WebSphere Liberty Debug.”
- Host: Set to
localhost(assuming the server runs on the same machine as IntelliJ IDEA; use the server’s IP address if it’s remote). - Port: Set to
7777(or the actual debug port if different). - Transport: Ensure it’s set to Socket.
- Debugger Mode: Select Attach (this tells IntelliJ to connect to an already-running JVM).
- Leave other settings (like “Command line arguments for remote JVM”) as default unless you need specific JVM options.
- Save the Configuration:
- Click Apply and then OK to save.
Step 4: Start Debugging
With the server running in debug mode and the configuration set up:
- Go to Run > Debug (or click the bug icon) and select your new configuration (e.g., “WebSphere Liberty Debug”).
- IntelliJ IDEA will attempt to attach to the server’s JVM on the specified host and port.
- If successful, you’ll see a message in the Debug window like “Connected to the target VM, address: ‘localhost:7777’.”
Step 5: Debug Your Application
- Set Breakpoints: In your source code, click in the gutter next to the line numbers to add breakpoints where you want execution to pause.
- Trigger Execution: Interact with your application (e.g., send a request to the server) to hit the breakpoints.
- Debug: Once a breakpoint is hit, use IntelliJ’s debugging tools (step over, step into, resume, etc.) to inspect variables and control execution.
Additional Notes
- Local vs. Remote Server: If WebSphere Liberty is running on a different machine, replace
localhostwith the server’s IP address in the remote debug configuration. Ensure the debug port (e.g., 7777) is open and not blocked by a firewall. - Port Conflicts: If port 7777 is unavailable when the server starts, WebSphere Liberty might pick a random port. Check the server output to confirm the port and update the IntelliJ configuration accordingly.
- No Plugin Needed: This method uses IntelliJ IDEA’s standard remote debugging feature, so no WebSphere Liberty plugin is required.
Summary
By starting your WebSphere Liberty Server with server debug default (which enables debugging on port 7777 by default) and configuring a remote debug setup in IntelliJ IDEA, you can connect to the server’s debug port without the WebSphere Liberty plugin. This gives you full debugging capabilities—breakpoints, variable inspection, and step-through execution—directly within IntelliJ IDEA.