Use QEMU in GitLab CI, not Docker image"

Is it Possible to Run QEMU or Firecracker Instead of Docker with GitLab CI?

GitLab CI is highly integrated with Docker, but sometimes projects which depend on the interaction with Linux kernel, such as LUKS, may not work properly. The project cryptsetup uses Travis-CI instead of GitLab CI even though it is hosted on gitlab.com.

Therefore, is it possible to run QEMU or Firecracker instead of Docker with GitLab CI? Is there an equivalent alternative to Travis-CI for GitLab?

Fenced code blocks should remain the same.

Yes, it is possible to run QEMU or Firecracker instead of Docker with GitLab CI. GitLab CI supports custom runners, which can be configured to use QEMU or Firecracker. As for an alternative to Travis-CI for GitLab, there is no need for an equivalent as GitLab CI can be configured to run any command or script, including those used by Travis-CI.