Setup basic authentication on kubernetes

Note: This is not recommended in a production environment. This is only for learning purposes.

Follow the below instructions to configure basic authentication in a kubeadm setup.

Create a file with user details locally at /tmp/users/user-details.csv

# User File Contents
password123,user1,u0001
password123,user2,u0002
password123,user3,u0003
password123,user4,u0004
password123,user5,u0005

Edit the kube-apiserver static pod configured by kubeadm to pass in the user details. The file is located at /etc/kubernetes/manifests/kube-apiserver.yaml

apiVersion: v1
kind: Pod
metadata:
  name: kube-apiserver
  namespace: kube-system
spec:
  containers:
  - command:
    - kube-apiserver
      <content-hidden>
    image: k8s.gcr.io/kube-apiserver-amd64:v1.11.3
    name: kube-apiserver
    volumeMounts:
    - mountPath: /tmp/users
      name: usr-details
      readOnly: true
  volumes:
  - hostPath:
      path: /tmp/users
      type: DirectoryOrCreate
    name: usr-details

Modify the kube-apiserver startup options to include the basic-auth file

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  name: kube-apiserver
  namespace: kube-system
spec:
  containers:
  - command:
    - kube-apiserver
    - --authorization-mode=Node,RBAC
      <content-hidden>
    - --basic-auth-file=/tmp/users/user-details.csv

Create the necessary roles and role bindings for these users:

---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  namespace: default
  name: pod-reader
rules:
- apiGroups: [""] # "" indicates the core API group
  resources: ["pods"]
  verbs: ["get", "watch", "list"]

---
# This role binding allows "jane" to read pods in the "default" namespace.
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: read-pods
  namespace: default
subjects:
- kind: User
  name: user1 # Name is case sensitive
  apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: Role #this must be Role or ClusterRole
  name: pod-reader # this must match the name of the Role or ClusterRole you wish to bind to
  apiGroup: rbac.authorization.k8s.io

Once created, you may authenticate into the kube-api server using the users credentials

curl -v -k https://localhost:6443/api/v1/pods -u "user1:password123"