Secure Docker Image from Being Copied or Encrypt Docker Image Contents
The root user on the host machine (where the docker daemon runs) has full access to all the processes running on the host. That means the person who controls the host machine can always get access to the RAM of the application as well as the file system. That makes it impossible to hide a key for decrypting the file system or protecting RAM from debugging.
Since you are sharing the image, You got no way to protect it from copying.
However using obfuscation on a standard Linux box, you can make it harder to read the file system and RAM, but you can't make it impossible or the container cannot run.