@kanekoh I'm not sure that hardcoding UID 1001 is a very good idea, since the mounted volumes from the host system will have now a "random" owner with UID 1001 .

@aadrian I understand that hardcoding UID is not good idea.

Which of these methods is closer to your thought?

1. No define "USER" instruction in Dockerfile
   As a default with docker-daemon, it works as a root uid container. However, a user can execute the container as non-root user with the parameter '-u'.

2. Use "ARG" instruction and set default value to define USERID in Dockerfile
   When the container image build with docker command, specify USERID with --build-arg. So, a user can change UID easily.

...
ARG USERID=1001
...
USER ${USERID}