The most significant claims include:
- Docker is insecure because Docker registries are not secured and “Docker does not know anything about either SELinux or AppArmor,” which help prevent security breaches on Linux systems.
- Building Docker applications requires writing scripts (or Dockerfiles, at least). Docker does not add value to the scripts; you could script application builds without Docker.
- Docker requires some apps to be rewritten to run in containers.
- Docker’s abstraction layers eat up CPU time, thereby undercutting the performance advantages that containers theoretically offer over virtual machines.
- The complexity required to run applications inside containers creates more trouble than it is worth.
- Administering Docker containers requires you to learn new commands.