Create an admin kubeconfig

create.sh

#!/usr/bin/env bash
set -ex

NAMESPACE="default"
NAME="admin"
SECRET_NAME="admin-secret"

kubectl create serviceaccount -n $NAMESPACE $NAME
kubectl create clusterrolebinding $NAMESPACE-$NAME --clusterrole=cluster-admin --serviceaccount=$NAMESPACE:$NAME

kubectl apply -f - <<EOF
apiVersion: v1
kind: Secret
metadata:
  name: $SECRET_NAME
  namespace: $NAMESPACE
  annotations:
    kubernetes.io/service-account.name: $NAME
type: kubernetes.io/service-account-token
EOF

TOKEN=$(kubectl get secret "${SECRET_NAME}" -ojsonpath='{.data.token}' | base64 -d)
CA=$(kubectl get secret "${SECRET_NAME}" -ojsonpath='{.data.ca\.crt}')
CURRENT_CONTEXT=$(kubectl config current-context)
CURRENT_CLUSTER=$(kubectl config view --raw -o=go-template='{{range .contexts}}{{if eq .name "'''"${CURRENT_CONTEXT}"'''"}}{{ index .context "cluster" }}{{end}}{{end}}')
CLUSTER_SERVER=$(kubectl config view --raw -o=go-template='{{range .clusters}}{{if eq .name "'''"${CURRENT_CLUSTER}"'''"}}{{ .cluster.server }}{{end}}{{ end }}')

FILENAME=$NAME-$(openssl rand -base64 3 | tr -dc '[:alnum:]' | head -c4).yaml

cat << EOF > "$FILENAME"
apiVersion: v1
kind: Config
current-context: ${CURRENT_CONTEXT}
contexts:
- name: ${CURRENT_CONTEXT}
  context:
    cluster: ${CURRENT_CONTEXT}
    user: $NAME
    namespace: $NAMESPACE
clusters:
- name: ${CURRENT_CONTEXT}
  cluster:
    certificate-authority-data: ${CA}
    server: ${CLUSTER_SERVER}
users:
- name: $NAME
  user:
    token: ${TOKEN}
EOF

echo "Created $FILENAME"