"Connection closed by foreign host." when trying to connect to remote pudb running in docker container

[piotr-dobrogost]

I started pudb in docker container (managed by docker compose) by setting
PYTHONBREAKPOINT=pudb.remote.set_trace
and placing breakpoint() in code (I also exposed port 6899 of the container in compose's yaml configuration).
In the container's console I see

pudb:6899: Please start a telnet session using a command like:
2024-02-08T10:59:45.149357228Z telnet 127.0.0.1 6899
2024-02-08T10:59:45.149367463Z pudb:6899: Waiting for client...

but I can't connect:

[piotr@demon]~/% telnet localhost 6899
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Connection closed by foreign host.

Any idea what might be the reason?

ps.
In Remote debugging section in the docs (https://documen.tician.de/pudb/starting.html#remote-debugging) there is no information on what to set PYTHONBREAKPOINT to in this case. It's not entirely obvious it should be set to pudb.remote.set_trace.

[piotr-dobrogost]

The solution was to call set_trace() passing host='0.0.0.0' instead of the default host='127.0.0.0' which makes pudb not accessible outside of a container.