Started to see a few dockers deprecate UID/GID environment variables now in favor of using the user param that can be passed when running/creating containers.

 

Would be nice with a GUI addition for it, now that we have the wonderful CPU pinning in the form it would be nice to build on it

 

Quote

USER

root (id = 0) is the default user within a container. The image developer can create additional users. Those users are accessible by name. When passing a numeric ID, the user does not have to exist in the container.

The developer can set a default user to run the first process with the Dockerfile USER instruction. When starting a container, the operator can override the USER instruction by passing the -u option.

-u="", --user="": Sets the username or UID used and optionally the groupname or GID for the specified command.

The followings examples are all valid:
--user=[ user | user:group | uid | uid:gid | user:gid | uid:group ]

Note: if you pass a numeric uid, it must be in the range of 0-2147483647.

 

https://docs.docker.com/engine/reference/run/#user

You can always use the ExtraParameters section of the template for the time being.