2019-06-09 afbjorklund
Three Sizes of Image
The bootable ISO file consists of two major components, the kernel and the filesystem.
The upstream image loads all modules and packages from the network, making it tiny:
Size: 15M
Contents
Besides the Linux kernel (vmlinuz64), there are three images (initrd) in /boot:
- corepure64.gz
- boot2podman.gz
- kubernetes.gz
These are stacked into the actual memory filesystem, using the boot configuration.
They are all stand-alone, in that they don’t require any further network download.
corepure64
The “corepure64” image is same as in Tiny Core Linux, with some minor modifications. 1
The kernel itself is not so big, but includes a lot of kernel modules that take up space:
Size: 35M = 5M + 30M
boot2podman
The “boot2podman” image adds all the packages needed to run Podman and Buildah. 2
Since most of them are statically linked, they take up twice as much as the base OS:
Size: 105M = 5M + 30M + 70M
kubernetes
The “kubernetes” image adds packages/images required to run Kubernetes with CRI-O.
By k3s combining functions into one binary and switching database, it still kept small:
Size: 175M = 5M + 30M + 70M + 70M
See: https://github.com/boot2podman/boot2podman/blob/master/remastering_tc.md