gardenlet/

README

Gardenlet Landscaper Component

This is a component of the Gardener Landscaper. Its purpose is to deploy a Gardenlet to a Kubernetes cluster and automatically register this cluster as a Seed resource in the Gardener installation.

It uses TLS bootstrapping with a bootstrap token to obtain a valid Gardenlet certificate for the Garden cluster. Essentially, it follows this documentation.

Prerequisites

The gardenlet landscaper deploys a VerticalPodAutoscaler resource if VPA for the Gardenlet is enabled (via field .deploymentConfiguration.vpa in the import configuration). Hence, in this case the Kubernetes cluster to be registered as a Seed must have Vertical Pod Autoscaling enabled (requires at least the CRD VerticalPodAutoscaler to be registered).

Run

The Gardenlet landscaper component is supposed to run as part of the Gardener Landscaper but can also be executed stand-alone.

The Gardenlet landscaper supports the following command line arguments:

• --integration-test --integration-test[=true|false] (defaults to false).

  In integration tests, we do not assume that the Gardenlet can be rolled out successfully, nor that the Seed can be registered. This is to provide an easy means of testing the landscaper component without requiring a fully functional Gardener control plane.

• --version version[=true|false|raw] Print version information and quit.

Make sure to set the following environment variables:

• IMPORTS_PATH contains the path to a file containing required import configuration.
• OPERATION is set to either RECONCILE (deploys the Gardenlet) or DELETE to remove the deployed resources.
• COMPONENT_DESCRIPTOR_PATH contains the path to a file containing a component descriptor for the Gardenlet. This file contains the OCI image reference to use for the Gardenlet deployment. You can find a sample descriptor here.

Run locally

1. Run make dev-setup to create a default component descriptor and import file for local execution in the directory dev/landscaper.

2. Adjust the import file landscaper/gardenlet-landscaper-imports.yaml to your setup. Please check what can be configured below.

3. Finally, run the below make statement to run the Gardenlet landscaper. This already sets the required environment variables and the path to the local imports and component descriptor file.

Run the landscaper gardenlet RECONCILE operation:

make start-landscaper-gardenlet OPERATION=RECONCILE

Run the landscaper gardenlet DELETE operation:

make start-landscaper-gardenlet OPERATION=DELETE

Import Configuration

Required configuration

• seedCluster contains the kubeconfig for the cluster

  • into which the Gardenlet is deployed by the landscaper
  • that is targeted as the Seed cluster by the Gardenlet via the default in-cluster mounted service account token

  Requires cluster-admin permissions.

• gardenCluster contains the kubeconfig for the Garden cluster. Requires admin permissions to create necessary RBAC roles and secrets.

• deploymentConfiguration configures the Kubernetes deployment of the Gardenlet. Specifies parameters, such as the number of replicas, the required resources, etc.

• componentConfiguration has to contain a valid component configuration for the Gardenlet.

• componentConfiguration.seedConfig must contain the Seed resource that will be automatically registered by the Gardenlet.

Forbidden configuration

Because the Gardenlet landscaper only supports TLS bootstrapping with a bootstrap token, setting the field .componentConfiguration.gardenClientConnection.kubeconfig in the import configuration is forbidden.

Deploying the Gardenlet outside the Seed cluster is not supported (e.g., landscaper deploys Gardenlet into cluster A and the Gardenlet is configured to target cluster B as Seed). Therefore, setting the field .componentConfiguration.seedClientConnection.kubeconfig in the import configuration is forbidden.

Default values

The field .componentConfiguration.gardenClientConnection.kubeconfigSecret defaults to:

kubeconfigSecret:
  name: gardenlet-kubeconfig
  namespace: garden

The field .componentConfiguration.gardenClientConnection.bootstrapKubeconfig defaults to:

bootstrapKubeconfig:
  name: gardenlet-kubeconfig-bootstrap
  namespace: garden

All other default values can be found in the Gardenlet Helm chart.

Seed Backup

The setup of etcd backup for the Seed cluster is optional. You can either a) refer to an existing secret in the Garden cluster containing backup credentials using the import configuration field componentConfiguration.seedConfig.backup b) or use the landscaper component to deploy a secret containing the backup credentials.

For option b), you need to provide the backup provider credentials in the import configuration field seedBackupCredentials. The Gardenlet landscaper takes care of creating a Kubernetes secret with the name and namespace given in componentConfiguration.seedConfig.backup.secretRef in the Garden cluster containing the credentials given in seedBackupCredentials.

Additional Considerations

If configured in componentConfiguration.seedConfig.secretRef, the landscaper will create a secret in the Garden cluster containing the kubeconfig of the Seed cluster. By default, the kubeconfig is taken from seedCluster.config.kubeconfig, or if specified, from .componentConfiguration.seedClientConnection.kubeconfig.