Switching users inside Docker image to a non-root user

You should not use su in a dockerfile, however you should use the USER instruction in the Dockerfile.

At each stage of the Dockerfile build, a new container is created so any change you make to the user will not persist on the next build stage.

For example:

RUN whoamiRUN su testRUN whoami

This would never say the user would be test as a new container is spawned on the 2nd whoami. The output would be root on both (unless of course you run USER beforehand).

If however you do:

RUN whoamiUSER testRUN whoami

You should see root then test.

Alternatively you can run a command as a different user with sudo with something like

sudo -u test whoami

But it seems better to use the official supported instruction.

As a different approach to the other answer, instead of indicating the user upon image creation on the Dockerfile, you can do so via command-line on a particular container as a per-command basis.

With docker exec, use --user to specify which user account the interactive terminal will use (the container should be running and the user has to exist in the containerized system):

docker exec -it --user [username] [container] bash

See https://docs.docker.com/engine/reference/commandline/exec/

Add this line to docker file

USER <your_user_name>

Use docker instruction USER