k3os | built OS for Kubernetes

Download the ISO from the latest release and run it in VMware, VirtualBox, KVM, or bhyve. The server will automatically start a single node Kubernetes cluster. Log in with the user rancher and run kubectl. This is a "live install" running from the ISO media and changes will not persist after reboot. To copy k3OS to local disk, after logging in as rancher run sudo k3os install. Then remove the ISO from the virtual machine and reboot. Live install (boot from ISO) requires at least 2GB of RAM. Local install requires 1GB RAM.
Interactive installation is done from booting from the ISO. The installation is done by running k3os install. The k3os install sub-command is only available on systems booted live. An installation to disk will not have k3os install. Follow the prompts to install k3OS to disk.
Installation can be automated by using kernel cmdline parameters. There are a lot of creative solutions to booting a machine with cmdline args. You can remaster the k3OS ISO, PXE boot, use qemu/kvm, or automate input with packer. The kernel and initrd are available in the k3OS release artifacts, along with the ISO. The cmdline value k3os.mode=install or k3os.fallback_mode=install is required to enable automated installations. Below is a reference of all cmdline args used to automate installation. By default k3OS expects one partition to exist labeled K3OS_STATE. K3OS_STATE is expected to be an ext4 formatted filesystem with at least 2GB of disk space. The installer will create this partitions and file system automatically, or you can create them manually if you have a need for an advanced file system layout.
You can install k3OS to a block device from any modern Linux distribution. Just download and run install.sh. This script will run the same installation as the ISO but is a bit more raw and will not prompt for configuration.
A special mode of installation is designed to install to a current running Linux system. This only works on ARM64 and x86_64. Download install.sh and run with the --takeover flag. This will install k3OS to the current root and override the grub.cfg. After you reboot the system k3OS will then delete all files on the root partition that are not k3OS and then shutdown. This mode is particularly handy when creating cloud images. This way you can use an existing base image like Ubuntu and install k3OS over the top, snapshot, and create a new image. In order for this to work a couple of assumptions are made. First the root (/) is assumed to be an ext4 partition. Also it is assumed that grub2 is installed and looking for the configuration at /boot/grub/grub.cfg. When running --takeover ensure that you also set --no-format and DEVICE must be set to the partition of /. Refer to the AWS packer template to see this mode in action. Below is any example of how to run a takeover installation.
If you have a custom ARMv7 or ARM64 device you can easily use an existing bootable ARM image to create a k3OS setup. All you must do is boot the ARM system and then extract k3os-rootfs-arm.tar.gz to the root (stripping one path, look at the example below) and then place your cloud-config at /k3os/system/config.yaml. For example:. This method places k3OS on disk and also overwrites /sbin/init. On next reboot your ARM bootloader and kernel should be loaded, but then when user space is to be initialized k3OS should take over. One important consideration at the moment is that k3OS assumes the root device is not read only. This typically means you need to remove ro from the kernel cmdline. This should be fixed in a future release.
Upgrading and reconfiguring k3OS is all handled through the Kubernetes operator. The operator is still in development. More details to follow. The basic design is that one can set the desired k3s and k3OS versions, plus their configuration and the operator will roll that out to the cluster.