Root password inside a Docker container

Question

I'm using a Docker image which was built using the USER command to use a non-root user called dev. Inside a container, I'm "dev", but I want to edit the /etc/hosts file.

So I need to be root. I'm trying the su command, but I'm asked to enter the root password.

What's the default root user's password inside a Docker container?

Answer 1

You can log into the Docker container using the root user (ID = 0) instead of the provided default user when you use the -u option. E.g.

docker exec -u 0 -it mycontainer bash

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.

from Docker documentation

Update: Of course you can also use the Docker management command for containers to run this:

docker container exec -u 0 -it mycontainer bash