Do breakpoints work for remote debug (of PHP on Docker)?

[rochgs]

Hello there 👋

I am debugging a PHP application set on a Docker container. For step debugging, I can use the xdebug_break() function, but breakpoints set by Dape are ignored. Looking at Xdebug's log file the problem seems to be that Dape is communicating the file path from the host:

[67] [Step Debug] WARN: Breakpoint file name does not exist: /home/rochgs/Code/core/src/Integrations/Checkout/Infrastructure/Api/Controller/ClientDataFormGetController.php (No such file or directory).

/home/rochgs/Code/core is the path in the host machine. That would be /var/www/html in the Docker container. However, I didn't find any settings in the documentation to set that.

Am I missing something? Is that even possible?

I am using:

• Dape: 0.24.1.
• Emacs: GNU Emacs 30.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.38, cairo version 1.16.0) of 2025-04-04, modified by Debian

Thank you,

[ivangrozni]

I'm also looking into setting up dape with docker/ddev. I'm coming from phpstorm and I'm looking forward to switch to Emacs for my php webdev. In phpstorm you have Servers with path mappings between host file system and in-docker file system.

I'll try to delve a bit into dap and dape by the end of the week and I'll let you know if I find out anything.

[rochgs]

@ivangrozni, really appreciated ❤️

[ivangrozni]

I tried a few things but wasn't successful yet.
My main source is: https://ddev.readthedocs.io/en/stable/users/debugging-profiling/step-debugging/#visual-studio-code-vs-code-debugging-setup
I tried creating a file .vscode/launch.json but it did not work for me. (another more on-point guide is here: https://davidloor.com/blog/how-to-set-up-xdebug-with-ddev-in-vscode-in-4-steps)

Secondly, I tried with the .dir-locals.el overrides. I tried this for my local docker setup:

(let ((xdebug-current (alist-get 'xdebug dape-configs)))
  (plist-put xdebug-current :port 10000)
  (plist-put xdebug-current :request "launch")
  (setq xdebug-local (plist-put xdebug-current :pathMappings "{ \"/app/web\": \"${workspaceFolder}\"}"))
  )

((php-mode . ((dape-configs . (add-to-list 'dape-configs xdebug-local)))))

but it did not work either.

I'll notify when/if I find a solution.

[rochgs]

@ivangrozni, thank you very much for the update.

I was thinking, maybe check what dap-mode does? I didn't try it, but it's supposed to work well with dockerized code.

[ivangrozni]

@rochgs check this issue: #183 looks like somebody found a way already

[rochgs]

@ivangrozni, thank you very much! That solved it for me. That's great because I was using dap-mode as a temporary replacemente and it doesn't work (for me) half well dape does.

I case it helps anybody reading this: I have multiple projects in different containers. To avoid manually adding the path parameters every time I start a dape session, I duplicated the basic xdebug configuration adding the params:

(let* ((xdebug-plist (cdr (assoc 'xdebug dape-configs)))
       (xdebug-project1-plist (copy-sequence xdebug-plist))
       (xdebug-project2-plist (copy-sequence xdebug-plist)))
  (setq xdebug-project1-plist (plist-put (plist-put (plist-put xdebug-project1-plist 'command-cwd "~/")
                                               'prefix-local "/path/to/project1/in/host/")
                                    'prefix-remote "/path/to/project1/in/container/"))
  (setq xdebug-proejct2-plist (plist-put (plist-put (plist-put xdebug-project2-plist 'command-cwd "~/")
                                                'prefix-local "/path/to/project2/in/host/")
                                     'prefix-remote "/path/to/project2/in/container/"))
  (setq dape-configs (append dape-configs `((xdebug-project1 . ,xdebug-project1-plist)
                                            (xdebug-project2 . ,xdebug-project2-plist)))))

Of course, if you have a single project, you can add the params to the basic xdebug configuration (although you probably are better keeping that in case you want to do local debugging).

[ivangrozni]

I'll try it out. I'm just wondering whether you have to specify the (local/host) domain anywhere?

[rochgs]

@ivangrozni, no. As far as you have xdebug properly set in your containers to try to connect to the host, that's where dape wills set up the dap server. I have this in my xdebug.ini:

xdebug.client_host=host.docker.internal

For that to work with linux, I needed to add this to docket-composer.yml (source):

extra_hosts:
            - "host.docker.internal:host-gateway"