Gitlab

Many cloud providers give you lots of memory with each instance and you can speed up tests and builds by using a ramdisk.

Buildah and podman work well with the vfs storage driver, but the default mount options can cause problems.

My team at Red Hat depends heavily on GitLab CI and we build containers often to run all kinds of tests.

My work at Red Hat involves testing lots and lots of kernels from various sources and we use GitLab CE to manage many of our repositories and run our CI jobs.