@atmoz
Actually, I am trying to build it in kubernetes.
I found I can access to sftp from a docker container.

In users.conf file,
foo:pass:1001: 100 :upload

I used the default sshd_config file from this repo.

I used WinSCP to connect the pod in kubernetes. The error is as bleow:

SFTP No supported authentication methods available (server sent: publickey)
Authentication log (see session log for details):
Using username "foo".
Authentication failed.