How to create a file instead of a directory?

Question

Docker

There is yml with text:

volumes:
      - dbdata:/var/lib/mysql/
      - type: bind
        target: /etc/mysql/my.cnf
        source: ./mysql/my.cnf

Gives an error message

Error response from daemon: OCI runtime create failed: container_linux.go:380: starting container process caused: process_linux.go:545: container init caused: rootfs_linux.go:76: mounting "/run/desktop/mnt/host/c/Users/пользователь/Desktop/sample/mysql/my.cnf" to rootfs at "/etc/mysql/my.cnf" caused: mount through procfd: not a directory: unknown: Are you trying to mount a directory onto a file (or vice-versa)? Check if the specified host path exists and is the expected type

And the my.cnf file itself exists. Already tried different options, it doesn’t work and deleted containers altogether and recreated, still trying to create as a directory, not as a file. Google solutions don't help.