kubeconfig

kubeconfig

As suggested in the directions at the end of the previous output we will allow a non-root user admin level access to the cluster. Take a quick look at the configuration file once it has been copied and the permissions fixed.

As a regular user, try to list k8s nodes

kubectl get nodes

The connection to the server localhost:8080 was refused - did you specify the right host or port?

As you can see, you cannot connect to the server because you do not have kubeconfig set. We copy the kubeconfig file from /etc/kubernetes/admin.conf to /home/student/.kube/config

as a regular user

mkdir -p $HOME/.kube

sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config

sudo chown $(id -u):$(id -g) $HOME/.kube/config

kubectl config view

apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: DATA+OMITTED
    server: https://master:6443
  name: desotech
contexts:
- context:
    cluster: desotech
    user: kubernetes-admin
  name: kubernetes-admin@desotech
current-context: kubernetes-admin@desotech
kind: Config
preferences: {}
users:
- name: kubernetes-admin
  user:
    client-certificate-data: REDACTED
    client-key-data: REDACTED

You can find the same output, without the certificate being redacted in the ~/.kube/config file.

less .kube/config

apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: <CERTIFICATE>
    server: https://master:6443
  name: desotech
contexts:
- context:
    cluster: desotech
    user: kubernetes-admin
  name: kubernetes-admin@desotech
current-context: kubernetes-admin@desotech
kind: Config
preferences: {}
users:
- name: kubernetes-admin
  user:
    client-certificate-data: <CERTIFICATE>
    client-key-data: <CERTIFICATE>

Running the same kubectl command now should allow you to view the nodes.

kubectl get nodes

NAME       STATUS     ROLES    AGE     VERSION
master01   NotReady   master   6m25s   v1.19.6

Now go to the student machine:

ssh student@student

mkdir -p $HOME/.kube

scp student@master01:.kube/config .kube/config

config      100% 5550   416.2KB/s   00:00

View the current context for kubectl

kubectl config current-context

kubernetes-admin@desotech

For display clusters defined in the kubeconfig

kubectl config get-contexts

CURRENT   NAME                        CLUSTER    AUTHINFO           NAMESPACE
*         kubernetes-admin@desotech   desotech   kubernetes-admin

To view the current cluster, run:

kubectl config get-clusters

NAME
desotech

Kubectl TAB completion bash

While many objects have short names, a kubectl command can be a lot to type. We will enable bash auto-completion. Start by adding the settings to the current shell. Then update the ~/.bashrc file to make it persistent.

source <(kubectl completion bash)

echo "source <(kubectl completion bash)" >> ~/.bashrc

Test by describing the node again. Type the first three letters of the sub-command then type the TAB key. Auto-completion assumes the default namespace. Pass the namespace first to use auto-completion with a different namespace. By pressing TAB multiple times you will see a list of possible values. Continue typing until a unique name is used. First look at the current node, then look at the pods in the kube-system namespace.

kubectl des<Tab> na<Tab> de<Tab>

kubectl describe namespaces default

kubectl -n kube-s<Tab> g<Tab> p<Tab>

kubectl -n kube-system get pod