Fails to start with `KeyError: WERKZEUG_SERVER_FD`

[hunger]

Describe the bug

gdbgui does not start. It fails with KeyError: WERKZEUG_SERVER_FD.

To Reproduce

1. pipx install gdbgui
2. gdbgui

I get this output:

1➜ gdbgui
Opening gdbgui with default browser at http://127.0.0.1:5000
View gdbgui dashboard at http://127.0.0.1:5000/dashboard
exit gdbgui by pressing CTRL+C
Traceback (most recent call last):
  File "/home/dev/.local/bin/gdbgui", line 8, in <module>
    sys.exit(main())
  File "/home/dev/.local/pipx/venvs/gdbgui/lib/python3.10/site-packages/gdbgui/cli.py", line 249, in main
    run_server(
  File "/home/dev/.local/pipx/venvs/gdbgui/lib/python3.10/site-packages/gdbgui/server/server.py", line 95, in run_server
    socketio.run(
  File "/home/dev/.local/pipx/venvs/gdbgui/lib/python3.10/site-packages/flask_socketio/__init__.py", line 596, in run
    app.run(host=host, port=port, threaded=True,
  File "/home/dev/.local/pipx/venvs/gdbgui/lib/python3.10/site-packages/flask/app.py", line 920, in run
    run_simple(t.cast(str, host), port, self, **options)
  File "/home/dev/.local/pipx/venvs/gdbgui/lib/python3.10/site-packages/werkzeug/serving.py", line 1047, in run_simple
    fd = int(os.environ["WERKZEUG_SERVER_FD"])
  File "/usr/lib/python3.10/os.py", line 679, in __getitem__
    raise KeyError(key) from None
KeyError: 'WERKZEUG_SERVER_FD'

The firefox browser pops up before this output shows up but only shows an empty page.

Expected behavior

Gbdgui starts up and does something.

Please complete the following information:

• OS: Linux
• gdbgui version (gdbgui -v): 0.15.0.1
• gdb version (gdb -v): GNU gdb (GDB) 11.2
• browser [e.g. chrome, safari]: It does not get to a point where that should matter:-)
• python packages (pip freeze):

appdirs==1.4.4
argcomplete==2.0.0
click==8.1.0
greenlet==1.1.2
lit==13.0.1.dev0
meson==0.62.0
more-itertools==8.10.0
msgpack==1.0.3
ordered-set==4.0.2
packaging==21.3
pipx==1.0.0
pynvim==0.4.3
pyparsing==3.0.7
six==1.16.0
TBB==0.2
userpath==1.8.0

Additional context
I tried running this inside an systemd-nspawn container, which does cause trouble sometimes. But this does not look like the typical container issue.

[saeugetier]

Try an older version of python library "werkzeug". Version 2.1.0 was faulty for me. Version 2.0.0 does work.

pip install werkzeug==2.0.0

[zenbooster]

Same problem.
Werkzeug==2.0.0

[hunger]

Can this be fixed upstream by pinning the expected werkzeug version somehow? This is a pretty bad first-use impression!

[saeugetier]

I think allways the latest version of Werkzeug is used. Werkzeug 2.1.0 is recently released: https://pypi.org/project/Werkzeug/#history
Maybe a patch is necessary to fix that problem.

[BIAOXYZ]

I also met this issue, solved by reinstallation of werkzeug 2.0.0

[davidism]

gdbgui/gdbgui/server/server.py

Line 93 in 799d340

os.environ["WERKZEUG_RUN_MAIN"] = "true"

This line is why it's failing. You're tricking Werkzeug into thinking it's running in the reloader, when it's not. This breaks the environment it expects to find when starting the server. Remove this line.

It seems this might have been done to enable debug=True while disabling the reloader? If that's the case, then the correct way to do that is to do app.run(debug=True, use_reloader=False).

[mattans]

gdbgui/gdbgui/server/server.py

Line 93 in 799d340

os.environ["WERKZEUG_RUN_MAIN"] = "true"

This line is why it's failing. You're tricking Werkzeug into thinking it's running in the reloader, when it's not. This breaks the environment it expects to find when starting the server. Remove this line.

It seems this might have been done to enable debug=True while disabling the reloader? If that's the case, then the correct way to do that is to do app.run(debug=True, use_reloader=False).

While I agree with you, expliciltly setting os.environ['WERKZEUG_RUN_MAIN'] = 'true' is a widely used trick to hide the console prints:

 * Serving Flask app '' (lazy loading)
 * Environment: development
 * Debug mode: off

Do you have an idea how to hide these prints in werkzeug 2.1.0? Because this will probably prevent many people from upgrading from werkzeug 2.0.0

[davidism]

You don't. That output is there for a reason, we want to very strongly make people aware that they are running a development server, and that it is not meant for production. The fact that setting an internal setup variable happened to suppress it was unintentional and never guaranteed to work.

"Production" means "not developing the application itself", even if it's a local application. The development server is not particularly secure, stable, or efficient. One way is to use a production server, such as waitress, which you can also import and run from Python code.

If you're really, really sure it's ok to run the development server and also don't want the output, then you can use make_server to create a server and call s.serve_forever() instead (possibly in a thread). This allows you to manually set up the server without all the other stuff that run_simple does. Again, be very very sure that running the development server is what you want for your users.

[mattans]

Thanks for the answer.

[scotter1995]

Installing werkzeug 2.0 hasn't actually solved the issue for me.

[otinkyad]

I get the same error as the OP, and installing werkzeug 2.0 does not solve the issue for me. Not sure if this is relevant: I'm running everything from within anaconda, on Xubuntu 20.04.

gdbgui with no customization did work for me about five days ago, but since that time I've reinstalled the OS and anaconda, pipx, and gdbgui, which seems consistent with something having changed in the last few days.

[ElectricLab]

Downgrading to 2.0.0 worked for me, on a newly installed Debian 11 system.