SeedImage reference

A SeedImage resource allows to build an installation media that can be used to install Elemental onto a node. It requires a baseImage, i.e., a URL to an Elemental installation ISO or node container image, and a registrationRef reference to a MachineRegistration resource, from which the registration part of the Elemental configuration is extracted and injected in the media to produce the final seed image. It is also possible to inject customizations in the cloud-config field. Both yip and cloud-init syntax are supported. See the Cloud Config Reference for full information.

Once the seed image is ready, the download URL is shared in the .status.downloadURL field. It stays available for download for cleanupAfterMinutes minutes (default is 60, 1 hour), after which it is deleted. Setting retriggerBuild to true retriggers the seed image build process while setting cleanupAfterMinutes to 0 keeps the seed image around till the SeedImage resource is deleted.

The SeedImage resource also has a type field which can be set to either iso, to build an ISO, or raw to build a raw disk image. Raw disk images can be copied directly to the target drive and on first boot will automatically boot into a recovery partition to expand the drive to use the available disk space and register the node, after which it will reboot the same way as for the ISO installation.

If no BuildContainer is specified for the seed-image it will be automatically filled in based on default values and type.

Building a SeedImage for a different platform is accomplished using the targetPlatform field. The platform is specified using os/arch, for example (linux/x86_64 or linux/aarch64). By default the image will be built for the same platform that the operator is hosted on.

seed images may fill up local storage

The seed images are kept on the node's local storage: pay attention to the number of SeedImage resources you start concurrently and to the ones you may leave around with the auto-cleanup feature disabled (cleanupAfterMinutes = 0) as you may exhaust the storage on your cluster nodes.

SeedImageSpec reference

Key	Type	Default value	Description
baseImage	string	empty	The base Elemental image used to build the seed image.
registrationRef	object ref.	null	A reference to a MachineRegistration that will be used for all installed machines to register.
buildContainer	object	null	Settings for a custom container used to generate the downloadable image. (See documentation).
cleanupAfterMinutes	int	60	The time after which the built seed image will be cleaned up. Active downloads will finish before the image is removed.
retriggerBuild	bool	false	Trigger to build again a cleaned up seed image.
size	string	6Gi	Specifies the size of the volume used to store the image.
type	string	iso	Specifies the type of seed image to built. iso or raw. (See documentation)
targetPlatform	string	empty	Specifies the target platform for the built image. Example: linux/x86_64 or linux/aarch64. (See documentation).
cloud-config	object	null	Contains cloud-config data to be included in the generated image. (See documentation).

BuildContainer

The buildContainer settings can be used to customize the build init container within the SeedImage's pod.
This could be the case for example when building custom Elemental images.

buildContainer:
  name: "custom-build"
  image: my.registry.com/elemental-custom-builder:1.2.3
  command:
    - build-image
  args:
    - foo
    - bar
  imagePullPolicy: Always

Note that the container will additionally have two volumes mounted at /iso and /overlay.
The SeedImage build process expects the build container to place the build artifact in /iso/$(ELEMENTAL_OUTPUT_NAME).

Configuration files are available in:

• /overlay/reg/livecd-cloud-config.yaml: A configuration file that can be used by elemental-register to register the machine.

• /overlay/iso-config/cloud-config.yaml: The cloud-config defined in SeedImage.spec.cloud-config

The following list of environment variables can also be used within the custom build container:

• ELEMENTAL_DEVICE: The MachineRegistration.spec.config.elemental.install.device value.
• ELEMENTAL_REGISTRATION_URL: The unique URL of the MachineRegistration.
• ELEMENTAL_BASE_IMAGE: The base image defined in the SeedImage.
• ELEMENTAL_OUTPUT_NAME: The expected file name of the build artifact.

ISO and Raw images

The SeedImage is able to build iso or raw image types.
Note that Elemental ships two different flavors of images, iso or container types. See ManagedOSversion's type.

When building a iso SeedImage, you can use an iso Elemental image.
iso images contain a pre-built .iso artifact. This is the default Elemental way of shipping official ISOs, so that they don't need to be rebuilt every time you define a SeedImage.

ISO SeedImage example

apiVersion: elemental.cattle.io/v1beta1
kind: SeedImage
metadata:
  name: fire-iso
  namespace: fleet-default
spec:
  type: iso
  baseImage: registry.suse.com/suse/sl-micro/6.0/baremetal-iso-image:2.1.1-3.36
  registrationRef:
    apiVersion: elemental.cattle.io/v1beta1
    kind: MachineRegistration
    name: fire-nodes
    namespace: fleet-default

Alternatively, when building a raw SeedImage, you should use container Elemental images. These images are also used during the upgrade process (See: ManagedOSImage), but can be used to build raw SeedImages as well.

Raw SeedImage example

apiVersion: elemental.cattle.io/v1beta1
kind: SeedImage
metadata:
  name: fire-raw
  namespace: fleet-default
spec:
  type: raw
  baseImage: registry.suse.com/suse/sl-micro/6.0/baremetal-os-container:2.1.1-3.29
  registrationRef:
    apiVersion: elemental.cattle.io/v1beta1
    kind: MachineRegistration
    name: fire-nodes
    namespace: fleet-default

Multi-Platform support

Elemental ships linux/x86_64 and linux/aarch64 images for most flavors.
In order to determine whether a ManagedOSVersion image supports both platforms, you can verify the ManagedOSVersion.spec.metadata.platform values. (See documentation).

When defining a SeedImage, you can then use this value for the image's targetPlatform.
Leaving the targetPlatform empty, will default to the platform where the elemental-operator is running.

Raw aarch64 SeedImage example

apiVersion: elemental.cattle.io/v1beta1
kind: SeedImage
metadata:
  name: fire-raw-aarch64
  namespace: fleet-default
spec:
  targetPlatform: linux/aarch64
  type: raw
  baseImage: registry.suse.com/suse/sl-micro/6.0/baremetal-os-container:2.1.1-3.29
  registrationRef:
    apiVersion: elemental.cattle.io/v1beta1
    kind: MachineRegistration
    name: fire-nodes
    namespace: fleet-default

Downloadable URLs

The SeedImage resource tracks the seed image build process through two status conditions:

• Ready: tracks the creation of all the required child resources that perform the actual build process.
• SeedImageReady: tracks the status of the build process in the child resources.

Alternatively it is also possible to wait for the SeedImage pod to be ready:

kubectl wait --for=condition=ready pod -n fleet-default fire-img

Waiting on Ready conditions is a best practice before downloading any artifact.

Once a SeedImage is ready, the .status.downloadURL will contain the downloadable URL.
Note that the URL will use the same endpoint as Rancher, so beware of HTTPS validation when using self signed certificates.

kubectl get seedimage -n fleet-default fire-img -o jsonpath="{.status.downloadURL}"

The checksum of the image is also available to verify the download was correct:

kubectl get seedimage -n fleet-default fire-img -o jsonpath="{.status.checksumURL}"