libgssapi_krb5.so.2 cannot be found when importing PySide6.QtWebEngineWidgets under Flatpak

[danverbraganza]

Describe the bug

Even though you're using the PySide6-supporting base image, if you use QtWebEngineWidgets, it relies on a library, libgssapi_krb5.so.2, which cannot be found.

This results in

libgssapi_krb5.so.2: cannot open shared object file: No such file or directory

Steps to reproduce

Build a standard PySide6 app. Make sure the runtime looks like

[tool.briefcase.app.my-app.linux.flatpak]                                                                                                                                                    
flatpak_runtime = "org.kde.Platform"                                                                                                                                                                
flatpak_runtime_version = "6.7"                                                                                                                                                                     
flatpak_sdk = "org.kde.Sdk"  

Within the app, arrange to call:

from PySide6.QtWebEngineWidgets import QWebEngineView

3. 💥

Expected behavior

Because the library was imported, we expect this should successfully work.

Screenshots

No response

Environment

• Operating System: Linux, Ubuntu 24.04 LTS
• Python version: 3.12
• Software versions:
  • Briefcase: 0.3.22

Logs

Additional context

Workaround

You can work around this by building mit-krb5 from source, by adding the following to your modules_extra_content

[tool.briefcase.app.my-app.linux.flatpak]
flatpak_runtime = "org.kde.Platform"
flatpak_runtime_version = "6.7"
flatpak_sdk = "org.kde.Sdk"

modules_extra_content = """
  - name: mit-krb5
    buildsystem: simple
    sources:
      - type: archive
        url: https://kerberos.org/dist/krb5/1.21/krb5-1.21.3.tar.gz
        sha256: b7a4cd5ead67fb08b980b21abd150ff7217e85ea320c9ed0c6dadd304840ad35
    build-commands:
      - cd src && autoreconf -i  # Ensure Autotools files are generated
      - cd src && ./configure --prefix=/app --disable-static --enable-shared
      - cd src && make -j$(nproc)
      - cd src && make install
"""

[freakboy3742]

Thanks for the report. This looks like a case of an extra snippet that can be added to the PySide6 bootstrap.

We have analogous snippets for web widget handling for Toga, because packaging for the web requires certain system packages - but we don't want to automatically include those system packages. So - we include the configuration item in the bootstrap, but leave it commented out with a docstring that indicates why you might need to turn this option on.