Docker - Failed to determine username

Hi ,
I am running confd in a docker container then i am getting error as Failed to determine user name on running confd_cli. Can anyone help. I am running docker with priviliged and added root user to admin group in the docker build.

Do you star confd_cli with -u?

E.g. confd_cli -u admin

Please also describe if confd_cli is running inside Docker or outside.