Backend busy waits if missing a starting folder

[daikema]

Describe the bug
Backend busy waits if missing a starting folder

To Reproduce
Steps to reproduce the behavior:

Start backend with params --no_http --port 3002 --top_level_folder /home/ubuntu --controller_deployment and you'll see output something like this:

[2023-11-10 15:28:50.285] [CARTA] [info] Writing to the log file: /home/ubuntu/.carta/log/carta.log
[2023-11-10 15:28:50.285] [CARTA] [warning] Option no_http found in commandline parameters is deprecated. Use no_frontend and no_database instead.
[2023-11-10 15:28:50.285] [CARTA] [debug] Using command-line settings
[2023-11-10 15:28:50.285] [CARTA] [info] /usr/bin/carta_backend: Version 4.0.0

Add /home/ubuntu as an additional parameter at the end and relaunch and the launch continues past whereever it hangs and will give you output like (and the continue normal operation) [CARTA] [info] Listening on port 3002 with top level folder /home/ubuntu, starting folder /home/ubuntu. The number of OpenMP worker threads will be handled automatically.

Expected behavior

Pick a sensible default (e.g. the top level folder) or report an error if no starting folder is provided.

Platform info (please complete the following information):

• OS [e.g. macOS Monterey]: Ubuntu 20.04 (minimalist docker container)
• Backend branch [e.g. dev, v3b2 release]: current backend package from PPA (4.0.0)

[kswang1029]

I though it will be $PWD (where carta_backend is executed)?🤔 Or your $PWD is outside top_level_folder?

[daikema]

As mentioned this is a minimalist container so $PWD would be undefined. (The backend would earlier error out when it couldn't find $HOME until I specified --no_log so that var didn't exist either). Currently have the container entrypoint set directly to the backend, so not even sure that there's a separate init process running (and definitely not a shell).

Should this get marked as container-too-minimalist/won't-fix then?