Debugging Externally Launched Remote Code
This section describes how to debug code launched on a remote host. These instructions are needed only if you cannot launch your code from Wing, for example if it runs under a web server or as an embedded script in a larger application.
The following instructions rely on Wing Pro's Remote Hosts feature to display and edit remote files. If you cannot use that feature for some reason, follow the instructions for Manually Configured Remote Debugging instead.
- First set up a remote host configuration as described in Remote Hosts and create a project that sets the Python Executable in Project Properties to the remote host and includes your remote source code. Before continuing, check that you can open remote files in Wing's editor.
- Copy wingdbstub.py from the directory where you installed the remote agent into the same directory as your debug program. By default this is ~/.wingpro10/remote-10.0.8.0/wingdbstub.py where ~ is the remote user's home directory. This will vary if you changed the Install Dir under the Advanced tab in the remote host configuration. If another copy of wingdbstub.py is used, configure it set WINGHOME to the installation directory of the remote agent and localhost:50050 for the Wing host and port.
- At the point where you want debugging to begin, insert the following into your code: import wingdbstub. If you are debugging code in an embedded Python instance, see the notes in Debugging Embedded Python Code. If you are debugging code running as a different user than the one in your remote host configuration, see Managing Permissions below.
- Make sure the Wing preference Debugger > Listening > Accept Debug Connections is turned on, to allow connection from external processes. Once this is enabled, Wing will start listening for connections on the remote host you configured in your project.
- Set any required breakpoints in your Python source code.
- Initiate the debug program from outside Wing in a way that causes it to import wingdbstub and reach a breakpoint or exception.
You should now see the status indicator in the lower left of the main Wing window change to yellow, red, or green, as described in Debugger Status. If no breakpoint or exception is reached, the program will run to completion, or you can use the Pause command in the Debug menu.
Managing Permissions
If your code is running as a different user than the one specified in your remote host configuration, as may be the case if running under Apache or another web server, then you will need to make some additional changes to make remote debugging work. For example, your remote host configuration may set Host Name to devel@192.168.0.50 so the user that installs the remote agent is devel while the code is actually run by the user apache.
In this case you must change the disk permissions on the Install Dir from which you copied wingdbstub.py so it can be read by the user that runs your debug process. The best way to do this is to create a group that includes both users and use that group for the directory, for example with chgrp -R groupname dirname.
Then change your copy of wingdbstub.py by replacing ~ with the full path to the home directory of the user in the remote host configuration. This is needed because ~ will expand to a different directory if the code is run as a different user.
You may also want to change the permissions on the debugger security token file wingdebugpw so that both users can read it, for example with chmod 640 wingdebugpw. The default for this file is to allow only the owner to read it. If this isn't done, Wing will generate a different debugger security token on the remote host and will initially reject your debug connection and prompt for you to accept the new security token. Once that is done, future debug connections will be accepted.
Changing Remote Debug Port
Remote debugging is implemented by listening locally and establishing a reverse SSH tunnel to the remote host configured in your project.
By default Wing listens on port 50050 on the remote host. Note that this is different than the default port used to listen on the local host, which is 50005, in order to prevent the remote agent from interfering with a local copy of Wing, when both are in use.
If this conflicts with another service on the remote host, or if there are multiple remote debug connections to a single host, you will need to change this port number to be unique for each developer. To do this, edit the Debug Port property under the Advanced tab of your remote host configuration and track this change in kWingHostPort in your copy of wingdbstub.py on the remote host.
You can verify that Wing is listening on the remote host and inspect the port number being used by hovering your mouse over the bug icon in the lower left of Wing's window.
Debugging on Multiple Remote Hosts
Wing listens locally and on the remote host specified in Python Executable in Project Properties. To listen on multiple hosts at once, use separate projects and multiple instances of Wing. You can open additional instances of Wing by adding --new to the command line.
Diagnosing Problems
If you have problems making this work, try setting the kLogFile variable in wingdbstub.py to log diagnostic information.
