Running a Container that is to be Debugged

This topic describes how to run a base image and volume mount an application's executable and debug files so that you can debug the application.

Note: This topic does not apply if you are using Visual COBOL Development Hub as a stand-alone development environment.

When you run the container, you must make sure that the docker run command specifies the following in addition to any parameters that you would normally specify:

If the application to be debugged is a native COBOL application, the entry point cobdebugremote (for 32-bit systems) or cobdebugremote64 (for 64-bit systems) to overwrite the default entry point for the container. This means that when the container runs it starts the process that is required to enable remote debugging rather than the entry point for the application that is to be debugged.
The port that the container will listen on. This must be specified by an EXPOSE command in the Dockerfile that was used to create the image.

For example, the following is a docker run command you could use to run the native COBOL Hello World Docker demonstration that had been built into an image for use on 64-bit Windows platforms:

docker run -p 6100 --rm 
 --name helloworld-x64-debug 
 -v %CD%\src\bin\x64\Debug:c:\app 
 --workdir c:\app 
 --entrypoint cobdebugremote64 
 -it microfocus/edbuildtools:win_4.0_x64 
 port=6100

The parameters specified in the above docker run command are as follows:

-p 6100: Publishes port number 6100. This must be specified by an EXPOSE command in the Dockerfile that was used to create the image.
--rm: Specifies that Docker will automatically remove the container when it finishes running.
--name helloworld-x64-debug: Specifies the name to be used for the container.
-v %CD%\src\bin\x64\Debug:c:\app: Mounts the local folder %CD%\src\bin\x64\Debug into the folder c:\app in the container. %CD% refers to the current directory and can only be used if you run the docker run command from a Windows batch file. If you run the command from the command line you can use the PowerShell automatic variable ${PWD} or specify the current directory in full.
--workdir c:\app: Sets the working directory for the container. This must be the same folder that is specified by the -v parameter.
--entrypoint cobdebugremote64: Specifies the 64-bit cobdebugremote64 module to enable remote debugging. This is only required for native COBOL applications.
-it: Specifies that the container runs interactively.
microfocus/edbuildtools:win_4.0_x64: Specifies the name of the image to run. In this case, this is the 64-bit Windows version of the Enterprise Developer Build Tools for Windows image.
port=6100: A command line paramter for the container.

When the container is running, if the application running is in native COBOL a message such as the following is displayed to indicate that the container is running and cobdebugremote (or cobdebugremote64) is ready to connect for debugging:

Waiting for a connection on machine IP-address/container-name using port port-number.
Press 'Q' to quit.