Create a kubeconfig File for Attachment

Create a separate service account when attaching existing clusters (for example Amazon EKS, or Azure AKS clusters)

If you already have a kubeconfig file to attach your cluster, go directly to Attach a Cluster with no Networking Restrictions (UI) or Attach a Cluster with Networking Restrictions.

The kubeconfig files generated from existing clusters are not usable out-of-the-box, because they call provisioner-specific CLI commands (like aws commands), and use locally-obtained authentication tokens that are not compatible with DKP. Having a separate service account also allows you to have a dedicated identity for all DKP operations.

To get started, ensure you have kubectl set up and configured with ClusterAdmin for the cluster you want to connect to Kommander.

1. Create the necessary service account:

   CODE

   kubectl -n kube-system create serviceaccount kommander-cluster-admin

2. Create a token secret for the serviceaccount:

   CODE

   kubectl -n kube-system create  -f - <<EOF
   apiVersion: v1
   kind: Secret
   metadata:
     name: kommander-cluster-admin-sa-token
     annotations:
       kubernetes.io/service-account.name: kommander-cluster-admin
   type: kubernetes.io/service-account-token
   EOF

3. Verify that the serviceaccount token is ready by running this command:

   CODE

   kubectl -n kube-system get secret kommander-cluster-admin-sa-token -oyaml

   Verify that the data.token field is populated. The output should be similar to this:

   NONE

   apiVersion: v1
   data:
     ca.crt: LS0tLS1CRUdJTiBDR...
     namespace: ZGVmYXVsdA==
     token: ZXlKaGJHY2lPaUpTVX...
   kind: Secret
   metadata:
     annotations:
       kubernetes.io/service-account.name: kommander-cluster-admin
       kubernetes.io/service-account.uid: b62bc32e-b502-4654-921d-94a742e273a8
     creationTimestamp: "2022-08-19T13:36:42Z"
     name: kommander-cluster-admin-sa-token
     namespace: default
     resourceVersion: "8554"
     uid: 72c2a4f0-636d-4a70-9f1c-55a75f15e520
   type: kubernetes.io/service-account-token

4. Configure the new service account for cluster-admin permissions:

   NONE

   cat << EOF | kubectl apply -f -
   apiVersion: rbac.authorization.k8s.io/v1
   kind: ClusterRoleBinding
   metadata:
     name: kommander-cluster-admin
   roleRef:
     apiGroup: rbac.authorization.k8s.io
     kind: ClusterRole
     name: cluster-admin
   subjects:
   - kind: ServiceAccount
     name: kommander-cluster-admin
     namespace: kube-system
   EOF

5. Set up the following environment variables with the access data that is needed for producing a new kubeconfig file:

   NONE

   export USER_TOKEN_VALUE=$(kubectl -n kube-system get secret/kommander-cluster-admin-sa-token -o=go-template='{{.data.token}}' | base64 --decode)
   export CURRENT_CONTEXT=$(kubectl config current-context)
   export CURRENT_CLUSTER=$(kubectl config view --raw -o=go-template='{{range .contexts}}{{if eq .name "'''${CURRENT_CONTEXT}'''"}}{{ index .context "cluster" }}{{end}}{{end}}')
   export CLUSTER_CA=$(kubectl config view --raw -o=go-template='{{range .clusters}}{{if eq .name "'''${CURRENT_CLUSTER}'''"}}"{{with index .cluster "certificate-authority-data" }}{{.}}{{end}}"{{ end }}{{ end }}')
   export CLUSTER_SERVER=$(kubectl config view --raw -o=go-template='{{range .clusters}}{{if eq .name "'''${CURRENT_CLUSTER}'''"}}{{ .cluster.server }}{{end}}{{ end }}')

6. Confirm these variables have been set correctly:

   NONE

   export -p USER_TOKEN_VALUE CURRENT_CONTEXT CURRENT_CLUSTER CLUSTER_CA CLUSTER_SERVER

7. Generate a kubeconfig file that uses the environment variable values from the previous step:

   NONE

   cat << EOF > kommander-cluster-admin-config
   apiVersion: v1
   kind: Config
   current-context: ${CURRENT_CONTEXT}
   contexts:
   - name: ${CURRENT_CONTEXT}
     context:
       cluster: ${CURRENT_CONTEXT}
       user: kommander-cluster-admin
       namespace: kube-system
   clusters:
   - name: ${CURRENT_CONTEXT}
     cluster:
       certificate-authority-data: ${CLUSTER_CA}
       server: ${CLUSTER_SERVER}
   users:
   - name: kommander-cluster-admin
     user:
       token: ${USER_TOKEN_VALUE}
   EOF

8. This process produces a file in your current working directory called kommander-cluster-admin-config. The contents of this file are used in Kommander to attach the cluster.
   Before importing this configuration, verify the kubeconfig file can access the cluster:

   NONE

   kubectl --kubeconfig $(pwd)/kommander-cluster-admin-config get all --all-namespaces

Next Step:

Use this kubeconfig to:

• Attach a cluster with no additional networking restrictions

• Attach a cluster that has networking restrictions

If a cluster has limited resources to deploy all the federated platform services, it will fail to stay attached in the DKP UI. If this happens, check if there are any pods that are not getting the resources required.