Continuous Integration, QA, Docker,...

Debugging Delphi applications inside a Windows Docker container

Hi there! Ever wondered how to deploy delphi applications inside a Windows Docker container? And how to debug them once they’re inside the container?  Search no more!  I will explain how to run a Windows Docker container with PAServer up and running, ready to debug your applications.

This can came in handy when:

  • Your service/app/… works great, but it fails miserably when it’s executed in a container and you need to debug it
  • You want  a quick & dirty deploy way of your service/app/… into a container, without the hassle of building a Dockerfile

Remember that in Windows containers you don’t have a GUI, so you only can run service-like apps (no VCL, no Firemonkey…).

The fast way

To follow this tutorial you’ll need:

Ok, let’s go ahead, follow these steps:

  • Run Docker for Windows
  • In context menu: Switch to Windows containers
  • Open powershell and run:
    • docker pull jaruzafa/paserverwindows
    • docker run -d -h mypaserver jaruzafa/paserverwindows
  • Now you have a Docker Windows container running PAServer at default port (64211) on  host “mypaserver”
  • Fire up RadStudio and open your project (or a console blank project just for testing)
  • Right-click on your target plataform (Windows 32 or 64) and select “Properties”
  • At “Profile” combo select “Add  New...”
    • Hostname: mypaserver
    • Port: 64211
    • No password
  • Important! If your target platform is Windows 32 make sure that: Project->Options->Delphi compiler->Linking->Include remote debug symbols->TRUE (otherwise you’ll get an error, eventually)
  • Click OK and set a breakpoint on your code.
  • Run with debug (or press F9) and wait until your breakpoint is reached 🙂
  • Enjoy the life

This video shows all the steps:

Under the hood

So you want to know what’s going on to hack it and customize for your own needs, right? Good, I love your attitude. Let’s go and take a look on what you need to debug delphi apps in a container.

The image

First of all we need to build an image with windows and PAServer installed and running. This Dockerfile will do the job:

FROM microsoft/windowsservercore
ADD install_paserver.bat /paserver/install_paserver.bat
ADD /paserver
WORKDIR /paserver
RUN install_paserver.bat
EXPOSE 64211
CMD ["/Program Files (x86)/Embarcadero/PAServer/19.0/paserver.exe"]

It downloads the PAServer setup package from Embarcadero servers, installs it, expose the port 64211, and starts paserver.exe

Pretty straightforward don’t you think? But wait… what’s that install_paserver.bat? why don’t just call setup_paserver.exe?

For some reason (unkown to me), setup_paserver.exe returns an error code=1, when running on silent mode. That error code breaks the docker build, so I came up with an install_paserver.bat that forces error code to 0:

setup_paserver.exe -i silent
exit /b 0

So far so good! Build the image (mind the point ‘.’ at the end, it’s important):

docker build -t paserverwindows .

After a while you’ll have the docker image, named “paserverwindows”.

The container

Now that you have the image, your next step is running it:

docker run -d -h mypaserver paserverwindows

RadStudio side

That’s it. It just works like a regular Remote Debugging project. You may name your container with a hostname using the -h parameter.

If you want to tune your PAServer with a password or a custom port you’ll need to copy out configuration file. If you need more info, go to PASever documentation.

Some thoughts

  • Source is available at
  • Unfortunately, I couldn’t use microsoft/nanoserver image (just sized 1GB) because it lacks of 32-bit Runtime, needed for PAServer.
  • You can run the container in interactive mode with:
    • docker run -i -h mypaserver jaruzafa/paserverwindows
    • But…. the console interface is quite laggy and it turn to be unusable. I have not found a solution to this, but if you come up with one, please leave a comment.

I hope you have enjoyed this post as much as I have enjoyed writing it. Comments, bug reports and thoughts will be highly appreciated!


  1. Alexsandro

    10/08/2018 at 18:45

    Theres way run in Windows Nano server?

    • jaruzafa

      11/08/2018 at 11:24

      Short answer is no Alexsandro.
      Since nanoserver cannot run Win32 applications (it can run just 64bit compiled binaries), and PAServer is a 32bit application, is not possible.

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