This document describes how a new seed cluster can be added to an existing Kubermatic master cluster.
Plese refer to the architecture diagrams for more information about the cluster relationships.
Kubermatic performs regular backups of user cluster by snapshotting the etcd of each cluster. By default these backups
are stored locally inside the cluster, but they can be reconfigured to work with any S3-compatible storage.
The in-cluster storage is provided by Minio and the accompanying
minio Helm chart.
If your cluster has no default storage class, it’s required to configure a class explicitely for Minio. You can check the cluster’s storage classes via:
kubectl get storageclasses #NAME PROVISIONER AGE #kubermatic-fast kubernetes.io/gce-pd 195d #standard (default) kubernetes.io/gce-pd 2y43d
As Minio does not require any of the SSD’s advantages, we can use HDDs. For a cluster running on AWS, an example class could look like this:
apiVersion: storage.k8s.io/v1 kind: StorageClass metadata: name: minio-hdd provisioner: kubernetes.io/aws-ebs parameters: type: sc1
To configure the storage class and size, extend your
values.yaml like so:
minio: storeSize: '500Gi' storageClass: minio-hdd
With this you can install the chart:
helm --tiller-namespace kubermatic upgrade --install --values /path/to/your/helm-values.yaml --namespace minio minio charts/minio/ helm --tiller-namespace kubermatic upgrade --install --values /path/to/your/helm-values.yaml --namespace s3-exporter s3-exporter charts/s3-exporter/
It’s also advisable to install the
s3-exporter Helm chart, as it provides basic metrics about user cluster backups.
This will need the creation of a secret named
s3-credentials in the
You can use the following command:
kubectl create secret -n s3-exporter generic s3-credentials --from-literal=ACCESS_KEY_ID=<aws_access_key_id> --from-literal=SECRET_ACCESS_KEY=<aws_secret_access_key>
To connect the new seed cluster with the master, you need to create a Secret containing the kubeconfig and a Seed resource.
You will add the master cluster as the seed cluster
Make sure the kubeconfig contains static, long-lived credentials. Some cloud providers use custom authentication providers
(like GKE using
gcloud and EKS using
aws-iam-authenticator). Those will not work in Kubermatic’s usecase because the
required tools are not installed inside the cluster environment.
You can follow the template below or use the yaml file inside the examples folder of the tarball.
apiVersion: v1 kind: Secret metadata: name: kubeconfig-europe-west1 namespace: kubermatic type: Opaque data: kubeconfig: <base64 encoded kubeconfig> --- apiVersion: kubermatic.k8s.io/v1 kind: Seed metadata: name: kubermatic namespace: kubermatic spec: # these two fields are only informational country: DE location: Hamburg # list of datacenters where this seed cluster is allowed to create clusters in datacenters:  # reference to the kubeconfig to use when connecting to this seed cluster kubeconfig: name: kubeconfig-europe-west1 namespace: kubermatic
Refer to the Seed CRD documentation for a complete example of the Seed CustomResource and all possible datacenters.
Apply the manifest above in the master cluster and Kubermatic will pick up the new Seed and begin to reconcile it by installing the required Kubermatic components.
The apiservers of all user cluster control planes running in the seed cluster are exposed by the
NodePort Proxy. By default each user cluster gets a virtual domain name like
for the Seed from the previous step when
kubermatic.example.com is the main domain where the
Kubermatic dashboard/API are available.
To facilitate this, a wildcard DNS record
*.[seed-name].[kubermatic-domain] must be created. The target of the
DNS wildcard record should be the
EXTERNAL-IP of the
nodeport-proxy service in the
When your cloud provider supports Load Balancers, you can find the target IP / hostname by looking at the
kubectl -n kubermatic get services #NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE #nodeport-proxy LoadBalancer 10.47.248.232 18.104.22.168 80:32014/TCP,443:30772/TCP 449d
EXTERNAL-IP is what we need to put into the DNS record.
Without a LoadBalancer, you will need to point to one or many of the seed cluster’s nodes. You can get a list of external IPs like so:
kubectl get nodes -o wide #NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP #worker-node-cbd686cd-50nx Ready <none> 3h36m v1.15.8-gke.3 10.156.0.36 22.214.171.124 #worker-node-cbd686cd-59s2 Ready <none> 21m v1.15.8-gke.3 10.156.0.14 126.96.36.199 #worker-node-cbd686cd-90j3 Ready <none> 45m v1.15.8-gke.3 10.156.0.22 188.8.131.52
Create an A or CNAME record as needed pointing to the target:
*.europe-west1.kubermatic.example.com. IN A 184.108.40.206
or, for a CNAME:
*.europe-west1.kubermatic.example.com. IN CNAME myloadbalancer.example.com.