Federated DaemonSet
Note: Federation V1, the current Kubernetes federation API which reuses the Kubernetes API resources ‘as is’, is currently considered alpha for many of its features, and there is no clear path to evolve the API to GA. However, there is a Federation V2 effort in progress to implement a dedicated federation API apart from the Kubernetes API. The details can be found at sig-multicluster community page.
This guide explains how to use DaemonSets in a federation control plane.
DaemonSets in the federation control plane (“Federated Daemonsets” in this guide) are very similar to the traditional Kubernetes DaemonSets and provide the same functionality. Creating them in the federation control plane ensures that they are synchronized across all the clusters in federation.
- Before you begin
- Creating a Federated Daemonset
- Updating a Federated Daemonset
- Deleting a Federated Daemonset
Before you begin
This guide assumes that you have a running Kubernetes Cluster Federation installation. If not, then head over to the federation admin guide to learn how to bring up a cluster federation (or have your cluster administrator do this for you). Other tutorials, such as Kelsey Hightower’s Federated Kubernetes Tutorial, might also help you create a Federated Kubernetes cluster.
You are also expected to have a basic working knowledge of Kubernetes in general and DaemonSets in particular.
Creating a Federated Daemonset
The API for Federated Daemonset is 100% compatible with the API for traditional Kubernetes DaemonSet. You can create a DaemonSet by sending a request to the federation apiserver.
You can do that using kubectl by running:
kubectl --context=federation-cluster create -f mydaemonset.yamlThe --context=federation-cluster flag tells kubectl to submit the
request to the Federation apiserver instead of sending it to a Kubernetes
cluster.
Once a Federated Daemonset is created, the federation control plane will create a matching DaemonSet in all underlying Kubernetes clusters. You can verify this by checking each of the underlying clusters, for example:
kubectl --context=gce-asia-east1a get daemonset mydaemonsetThe above assumes that you have a context named ‘gce-asia-east1a’ configured in your client for your cluster in that zone.
Updating a Federated Daemonset
You can update a Federated Daemonset as you would update a Kubernetes DaemonSet; however, for a Federated Daemonset, you must send the request to the federation apiserver instead of sending it to a specific Kubernetes cluster. The federation control plane ensures that whenever the Federated Daemonset is updated, it updates the corresponding DaemonSets in all underlying clusters to match it.
Deleting a Federated Daemonset
You can delete a Federated Daemonset as you would delete a Kubernetes DaemonSet; however, for a Federated Daemonset, you must send the request to the federation apiserver instead of sending it to a specific Kubernetes cluster.
For example, you can do that using kubectl by running:
kubectl --context=federation-cluster delete daemonset mydaemonset