In this guide, we will find out how to create a new user using Service Account mechanism of Kubernetes, grant this user admin permissions and log in to Dashboard using bearer token tied to this user.
We are creating Service Account with name my-admin-user in namespace kube-system first.
kubectl create serviceaccount my-admin-user -n kube-system
kubectl get sa
In most cases after provisioning our cluster using kops or kubeadm or any other popular tool, the ClusterRole admin-Role already exists in the cluster. We can use it and create only ClusterRoleBinding for our ServiceAccount.
kubectl create clusterrolebinding my-admin-user -n kube-system --clusterrole=cluster-admin --serviceaccount=kube-system:my-admin-user
Now we need to find token we can use to log in. Execute following command:
kubectl get secret $(kubectl get serviceaccount my-admin-user -n kube-system -o jsonpath="{.secrets[0].name}") -o jsonpath="{.data.token}" -n kube-system | base64 --decode
It should print something like:
eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJrdWJlcm5ldGVzL3NlcnZpY2VhY2NvdW50Iiwia3ViZXJuZXRlcy5pby9zZXJ2aWNlYWNjb3VudC9uYW1lc3BhY2UiOiJrdWJlLXN5c3RlbSIsImt1YmVybmV0ZXMuaW8vc2VydmljZWFjY291bnQvc2VjcmV0Lm5hbWUiOiJhZG1pbi11c2VyLXRva2VuLTZnbDZsIiwia3ViZXJuZXRlcy5pby9zZXJ2aWNlYWNjb3VudC9zZXJ2aWNlLWFjY291bnQubmFtZSI6ImFkbWluLXVzZXIiLCJrdWJlcm5ldGVzLmlvL3NlcnZpY2VhY2NvdW50L3NlcnZpY2UtYWNjb3VudC51aWQiOiJiMTZhZmJhOS1kZmVjLTExZTctYmJiOS05MDFiMGU1MzI1MTYiLCJzdWIiOiJzeXN0ZW06c2VydmljZWFjY291bnQ6a3ViZS1zeXN0ZW06YWRtaW4tdXNlciJ9.M70CU3lbu3PP4OjhFms8PVL5pQKj-jj4RNSLA4YmQfTXpPUuxqXjiTf094_Rzr0fgN_IVX6gC4fiNUL5ynx9KU-lkPfk0HnX8scxfJNzypL039mpGt0bbe1IXKSIRaq_9VW59XNow copy the token and paste it into Enter token field on log in screen.
Click Sign in button and that's it. You are now logged in as an admin.
In order to find out more about how to grant/deny permissions in Kubernetes read official authentication & authorization documentation.