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Remote Debugging

Remote debug an ASP.NET application running in Windows 2016 PCF containers



  • Create a simple ASP.NET web forms application. (Use an existing one, if you have already)

    • Open Visual studio and navigate to File->New Project
    • Select ASP.NET Web Forms and follow the instructions to create the application
    • Make sure to do run the application (F5 or Ctl+F5) and ensure that the application is working fine
  • Publish the application in Debug mode

    • Right click on the Project in Solution explorer
    • Select Publish Web App, in the opened window, under Connection tab, select File System as Publish Method
    • Choose a target location for the published artifacts, in my sample I chose c:\AppArtifacts\RemoteDebugging
    • Under Settings tab, select Debug as Configuration
    • Expand File Publish Options and select all the check boxes
    • Click on Configure link near to Precompile during publish option, a new window will be opened
    • Make sure to check Emit debug information. It is very important to select debug info emit option, else no symbols will be loaded for debugging.
    • Other options are optional and make it as appropriate. In my case, I checked Allow precompiled site to be updatable and selected Do not merge options
    • Press Ok button takes you to the parent form where you can click Publish
    • Once publish is successfully completed, you can navigate to the targeted location, in my case c:\AppArtifacts\RemoteDebugging, where I should see all the published artifacts.
  • Now, we need to find the appropriate remote debugging tools, for the version of Visual Studio you are using. In my case I used Visual Studio 2017.

    • You can use some simple tips to find it out. In windows explorer, navigate to c:\ and search for msvsmon.exe. This will show you number of locations based on the number of Visual Studio version you have.

    • In my case, since I have Visual studio 2017, I chose C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\Common7\IDE\Remote Debugger\x64

    • Create a new folder called vs_dubugger under our artifacts directory, e.g. c:\AppArtifacts\RemoteDebugging\vs_dubugger

    • Copy all the files and folders recursively from the identified remote tools folder C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\Common7\IDE\Remote Debugger\x64\* to c:\AppArtifacts\RemoteDebugging\vs_dubugger

    • You can follow the above commands from power shell as below. Open PowerShell in Administrator mode and execute the below commands. Modify the path and variables accordingly.

      PS C:\> md c:\AppArtifacts\RemoteDebugging\vs_dubugger
      PS C:\> cp -Recurse -Force C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\Common7\IDE\Remote Debugger\x64\* c:\AppArtifacts\RemoteDebugging\vs_dubugger
  • Make sure you have the remote tools are copied by executing the below commands. It should open a window showing the help document of the tool msvsmon.exe

    PS C:\> cd c:\AppArtifacts\RemoteDebugging\vs_dubugger
    PS C:\AppArtifacts\RemoteDebugging\vs_dubugger> .\msvsmon.exe
  • Push the application to PCF

    • Make sure you have installed and logged in into CF CLI, ensure by executing the command cf target. This should show the endpoint, org, space details, etc.

    • Navigate to the artifacts directory and do a cf push, make sure the app is being pushed to Windows2016 stack

      PS C:\> cd c:\AppArtifacts\RemoteDebugging 
      PS C:\AppArtifacts\RemoteDebugging> cf push <app_name> -s Windows2016 -b hwc_buildpack
    • You can use cf app <app_name> and find the status of the running app. You can also, either curl or launch the app in any browser of your choice. Make sure the app is running properly.

  • SSH and setting up remote debugger in the container

    • You can ssh into the container using the below PS command. Type to cf ssh --help for more details on ssh command. Also you can use any port, not necessarily 4020

      PS C:\> cf ssh <app_name> -L 4020:localhost:4020
    • If connected successfully, you should see some thing like below

      Microsoft Windows [Version 10.0.16299.492]
      (c) 2017 Microsoft Corporation. All rights reserved.
    • Now you can continue following the below PS commands, here we navigate to the vs_debugger folder where we copied the remote tools into

      C:\Users\vcap> powershell
      PS C:\Users\vcap>cd app
      PS C:\Users\vcap\app>cd vs_debugger
      PS C:\Users\vcap\app\vs_debugger> ls
    • Launching the debugger, in my case i used port 4020

      PS C:\Users\vcap\app\vs_debugger> .\msvsmon.exe /noauth /silent /nosecuritywarn /anyuser /port 4020
      PS C:\Users\vcap\app\vs_debugger> ps
    • This should list all the running processes, you can filter using ps | findstr msvsmon, where you should be able to see msvsmon.exe up and running. You should see something similar to below

      196      12     2196       8656       0.05    392   4 msvsmon
      140       9     1584       7136       0.03   4092   4 msvsmon
    • To check the ports, use the below PS commands

      PS C:\Users\vcap\app\vs_debugger> ps
    • You can use filters like netstat -aon | findstr 4020 where you should see some results as below

      TCP               LISTENING       4092
      TCP    [::]:4020              [::]:0                 LISTENING       4092
    • Now that your container and the app instance is all set for debugging

  • Connecting Visual Studio debugger to the remote container

    • Open the application you are trying to debug, in Visual Studio (make sure it should be of the same version of remote tools you pushed into the container)
    • Navigate to Debug menu and click on Attach to Process, Or use shortcut Alt+D+P. A new window will open.
    • For Attached To, Click the Select button so that a window will be opened with various attach options, Here you check Managed (v4.6, v4.5, v4.0) code only and uncheck rest . By default it will be set to Automatically determined
    • Go to Connection Type and select Remote (no authentication) from the dropdown. By default it will be selected as Default
    • Go to Connection Target and type localhost:4020 and press Enter. Here 4020 is the port I opened for tunneling into the container, refer to above steps if not sure.
    • Now you should see all the process running in the container, under Available Processes list.
    • Select hwc.exe and click Attach button. You should see the symbols being loaded and ready to debug.
    • You can set your break points as such and invoke via browser, should see debugger hitting the breakpoint.
  • Recording available @

Hope you have fun debugging!