How to build raw disk images for Raspberry Pi

This guide will show how we can build a raw disk image that can be written to an SD-card and booted without any other installation media.

caution

Any data on the SD-card will be erased, please only use a SD-card without anything important on it.

The SD-card must be reasonably large (32 GB or more) and fast (!!).

SeedImage resource

apiVersion: elemental.cattle.io/v1beta1
kind: SeedImage
metadata:
  name: fire-img
  namespace: fleet-default
spec:
  type: raw
  baseImage: registry.opensuse.org/isv/rancher/elemental/dev/containers/suse/sle-micro/5.5:latest
  targetPlatform: linux/arm64
  registrationRef:
    apiVersion: elemental.cattle.io/v1beta1
    kind: MachineRegistration
    name: fire-nodes
    namespace: fleet-default

Check the logs for the build pod using:

kubectl logs -n fleet-default fire-img -f -c build

When the build is finished we can download the image file using wget:

wget --no-check-certificate $(kubectl get seedimage -n fleet-default fire-img -o jsonpath="{.status.downloadURL}") -O sle-micro.arm64.raw

Now we can write the .raw image to the SD-card. This can be done with dd on the Linux command line if you're comfortable with this command. openSUSE has nice instructions on how to write an image to a storage medium for Linux, Windows, and OS X.

Starting the machine

The raw disk image will only include the EFI partition, OEM partition and recovery partition. On first boot the system will boot into the recovery system to expand and add missing partitions. After expansion it will register with rancher and reboot.

If an error occurs during registration phase the journal can be found using journalctl -u elemental-register-reset.