This document discusses modernizing RancherOS, a micro Linux distribution. It describes replacing System Docker with runC and Containerd to reduce size and improve performance. Through iterative changes like removing unused files, generating container specs, and customizing services, the initrd size was reduced from 245MB to 190MB and boot time from 30 seconds to 12 seconds. The final version can boot and serve HTTP requests within 7 seconds while maintaining compatibility with RancherOS.