Is it possible to access a user created on the main system from within a container?

By default, a container has an isolated environment, and users of the main system (host) are not visible inside the container. However, if a user with the same UID and GID is created inside the container, processes inside the container can run as that user.

There is no direct access to the host user from the container, but it is possible to:

• Create a user with the same UID/GID inside the container to match permissions.
• Use directory mounting with access rights corresponding to the host user.
• Run the container with parameters that allow using the host user (for example, --user $(id -u):$(id -g) in Docker).

Thus, access to the host user inside the container is possible through coordination of identifiers and permission settings, but not directly "out of the box".