managed_seed.md

Register Shoot as Seed

An existing shoot can be registered as a seed by creating a ManagedSeed resource. This resource replaces the use-as-seed annotation that was previously used to create shooted seeds. It contains:

• The name of the shoot that should be registered as seed.
• An optional seedTemplate section that contains the Seed spec and parts of its metadata, such as labels and annotations.
• An optional gardenlet section that contains:
  • gardenlet deployment parameters, such as the number of replicas, the image, etc.
  • The GardenletConfiguration resource that contains controllers configuration, feature gates, and a seedConfig section that contains the Seed spec and parts of its metadata.
  • Additional configuration parameters, such as the garden connection bootstrap mechanism (see TLS Bootstrapping), and whether to merge the provided configuration with the configuration of the parent gardenlet.

Either the seedTemplate or the gardenlet section must be specified, but not both:

• If the seedTemplate section is specified, gardenlet is not deployed to the shoot, and a new Seed resource is created based on the template.
• If the gardenlet section is specified, gardenlet is deployed to the shoot, and it registers a new seed upon startup based on the seedConfig section of the GardenletConfiguration resource.

Note the following important aspects:

• Unlike the Seed resource, the ManagedSeed resource is namespaced. Currently, managed seeds are restricted to the garden namespace.
• The newly created Seed resource always has the same name as the ManagedSeed resource. Attempting to specify a different name in seedTemplate or seedConfig will fail.
• The ManagedSeed resource must always refer to an existing shoot. Attempting to create a ManagedSeed referring to a non-existing shoot will fail.
• A shoot that is being referred to by a ManagedSeed cannot be deleted. Attempting to delete such a shoot will fail.
• You can omit practically everything from the seedTemplate or gardenlet section, including all or most of the Seed spec fields. Proper defaults will be supplied in all cases, based either on the most common use cases or the information already available in the Shoot resource.
• Some Seed spec fields, for example the provider type and region, networking CIDRs for pods, services, and nodes, etc., must be the same as the corresponding Shoot spec fields of the shoot that is being registered as seed. Attempting to use different values (except empty ones, so that they are supplied by the defaulting mechanims) will fail.

Deploying Gardenlet to the Shoot

To register a shoot as a seed and deploy gardenlet to the shoot using a default configuration, create a ManagedSeed resource similar to the following:

apiVersion: seedmanagement.gardener.cloud/v1alpha1
kind: ManagedSeed
metadata:
  name: my-managed-seed
  namespace: garden
spec:
  shoot:
    name: crazy-botany
  gardenlet: {}

For an example that uses non-default configuration, see 55-managed-seed-gardenlet.yaml

Creating a Seed from a Template

To register a shoot as a seed from a template without deploying gardenlet to the shoot using a default configuration, create a ManagedSeed resource similar to the following:

apiVersion: seedmanagement.gardener.cloud/v1alpha1
kind: ManagedSeed
metadata:
  name: my-managed-seed
  namespace: garden
spec:
  shoot:
    name: crazy-botany
  seedTemplate:
    metadata:
      labels:
        seed.gardener.cloud/gardenlet: local
    spec:
      dns:
        ingressDomain: ""
      networks:
        pods: ""
        services: ""
      provider:
        type: ""
        region: ""

Note the seed.gardener.cloud/gardenlet: local label above. It stands for the label that is used in a seedSelector field of a gardenlet that takes care of multiple seeds. This label can be omitted if the seedSelector field selects all seeds. If there is no gardenlet running outside the cluster and selecting the seed, it won't be reconciled and no shoots will be scheduled on it.

For an example that uses non-default configuration, see 55-managed-seed-seedtemplate.yaml