This document describes how a new seed cluster can be added to an existing KKP master cluster.
For smaller scale setups it’s possible to use the existing master cluster as a seed cluster (a “shared” cluster installation). In this case both master and seed components will run on the same cluster and in the same namespace. It is however not possible to use the same cluster for multiple seeds.
Please refer to the architecture diagrams for more information about the cluster relationships.
Compared to master clusters, seed clusters are still mostly manually installed. Future versions of KKP will improve the setup experience further.
When using Helm 2, install Tiller into the seed cluster first:
kubectl create namespace kubermatic
kubectl create serviceaccount -n kubermatic tiller
kubectl create clusterrolebinding tiller-cluster-role --clusterrole=cluster-admin --serviceaccount=kubermatic:tiller
helm --service-account tiller --tiller-namespace kubermatic init
KKP performs regular backups of user cluster by snapshotting the etcd of each cluster. By default these backups
are stored locally inside the seed 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 explicitly for Minio. You can check the cluster’s storage classes via:
kubectl get storageclasses
#NAME PROVISIONER AGE
#kubermatic-fast kubernetes.io/aws-ebs 195d
#kubermatic-backup kubernetes.io/aws-ebs 195d
#standard (default) kubernetes.io/aws-ebs 2y43d
As Minio does not require any of the SSD’s advantages, we can use HDDs. It’s recommended to create a separate storage class kubermatic-backup with a different location/security level. For a cluster running on AWS, an example class could look like this:
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: kubermatic-backup
provisioner: kubernetes.io/aws-ebs
parameters:
type: sc1
To configure the storage class and size, extend your values.yaml. For more information about the Minio options, take a look at minio chart values.yaml and the min.io documentation - S3 gateway:
minio:
storeSize: '200Gi'
# SC will store the etcd backup of the seed hosted user clusters
storageClass: kubermatic-backup
# access key/secret for the exposed minio S3 gateway
credentials:
# generated access key length should be at least 3 characters
accessKey: "YOUR-ACCESS-KEY"
# generated secret key length should be at least 8 characters
secretKey: "YOUR-SECRET-KEY"
It’s also advisable to install the s3-exporter Helm chart, as it provides basic metrics about user cluster backups.
With this you can install the charts:
Helm 3
helm --namespace minio upgrade --install --wait --values /path/to/your/helm-values.yaml minio charts/minio/
helm --namespace kube-system upgrade --install --wait --values /path/to/your/helm-values.yaml s3-exporter charts/s3-exporter/
Helm 2
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 kube-system s3-exporter charts/s3-exporter/
To connect the new seed cluster with the master, you need to create a kubeconfig Secret and a Seed resource. This allows the KKP components in the master cluster to communicate with the seed cluster and reconcile user-cluster control planes.
To make sure that the kubeconfig stays valid forever, it must not contain temporary login tokens. Depending on the
cloud provider, the default kubeconfig that is provided may not contain username+password / a client certificate, but instead
try to talk to local token helper programs like aws-iam-authenticator for AWS or gcloud for the Google Cloud (GKE).
These kubeconfig files will not work for setting up Seeds.
The KKP repository provides a script that can be used to prepare a kubeconfig for usage in KKP. The script will create
a ServiceAccount in the seed cluster, bind it to the cluster-admin role and then put the ServiceAccount’s token into
the kubeconfig file. Afterwards the file can be used in KKP.
The Seed resource then needs to reference the new kubeconfig Secret like so:
apiVersion: v1
kind: Secret
metadata:
name: kubeconfig-europe-west3
namespace: kubermatic
type: Opaque
data:
# You can use `base64 -w0 my-kubeconfig-file` to encode the
# kubeconfig properly for inserting into this Secret.
kubeconfig: <base64 encoded kubeconfig>
---
apiVersion: kubermatic.k8s.io/v1
kind: Seed
metadata:
name: europe-west3
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-west3
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 KKP will pick up the new Seed and begin to
reconcile it by installing the required Kubermatic components. You can watch the progress by using
kubectl and watch:
kubectl apply -f seed-with-secret.yaml
Secret/kubeconfig-europe-west3 created.
Seed/europe-west3 created.
watch kubectl -n kubermatic get pods
#NAME READY STATUS RESTARTS AGE
#kubermatic-api-55765568f7-br9jl 1/1 Running 0 5m4s
#kubermatic-api-55765568f7-xbvz2 1/1 Running 0 5m13s
#kubermatic-dashboard-5d784d586b-f46f8 1/1 Running 0 35m
#kubermatic-dashboard-5d784d586b-rgl29 1/1 Running 0 35m
#kubermatic-master-controller-manager-f58d4df59-w7rkz 1/1 Running 0 5m13s
#kubermatic-operator-7f6957869d-89g55 1/1 Running 0 5m37s
#nodeport-proxy-envoy-6d8bb6fbff-9z57l 2/2 Running 0 5m6s
#nodeport-proxy-envoy-6d8bb6fbff-dl58l 2/2 Running 0 4m54s
#nodeport-proxy-envoy-6d8bb6fbff-k4gp8 2/2 Running 0 4m44s
#nodeport-proxy-updater-7fd55f948-cll8n 1/1 Running 0 4m44s
#seed-proxy-europe-west3-6dd5cc95cf-r6wvb 1/1 Running 0 80m
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
[cluster-id].[seed-name].[kubermatic-domain], e.g. hdu328tr.europe-west3.kubermatic.example.com
for the Seed from the previous step when kubermatic.example.com is the main domain where the
KKP 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 kubermatic namespace.
When your cloud provider supports LoadBalancers, you can find the target IP / hostname by looking at the
nodeport-proxy Service:
kubectl -n kubermatic get services
#NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
#nodeport-proxy LoadBalancer 10.47.248.232 8.7.6.5 80:32014/TCP,443:30772/TCP 449d
The 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 8.7.6.4
#worker-node-cbd686cd-59s2 Ready <none> 21m v1.15.8-gke.3 10.156.0.14 8.7.6.3
#worker-node-cbd686cd-90j3 Ready <none> 45m v1.15.8-gke.3 10.156.0.22 8.7.6.2
Create an A or CNAME record as needed pointing to the target:
*.europe-west3.kubermatic.example.com. IN A 8.7.6.5
or, for a CNAME:
*.europe-west3.kubermatic.example.com. IN CNAME myloadbalancer.example.com.