LAB02: Get Cluster Basic & Detailed Information

LAB02 Get Cluster Basic & Detailed Information

Lab Goals

By the end of this lab, students will be able to:

• Explore kubeconfig file & contexts

• View Kubernetes certificates

• Inspect static pod manifests (control plane components)

• Find cluster name, API server endpoint

• Connect a Kubernetes cluster to Lens

• Retrieve essential cluster metadata using kubectl commands

** Prerequisites**

• A running Kubernetes cluster (K8s ≥ 1.30).

• CLI tools: kubectl, sudo access.

• Lens installed (optional but recommended).

** PART 1: Kubeconfig & Cluster Access**

1.1 View kubeconfig file

By default kubeconfig is located at:

~/.kube/config

Check the file:

cat ~/.kube/config

Key information inside kubeconfig:

• clusters: name, API server URL

• contexts: combination of cluster + user

• users: client certs or tokens

• current-context: default cluster your kubectl is talking to

View current context:

kubectl config current-context

List contexts:

kubectl config get-contexts

Switch context:

kubectl config use-context <context-name>

** PART 2: Kubernetes Certificates**

Control plane certificates are stored in:

/etc/kubernetes/pki/

List certificates:

sudo ls -l /etc/kubernetes/pki/

Important files:

• ca.crt → K8s root CA

• apiserver.crt → API server certificate

• apiserver-kubelet-client.crt

• front-proxy-ca.crt

• etcd/ → etcd certificates

Check certificate validity:

openssl x509 -in /etc/kubernetes/pki/apiserver.crt -text -noout

Check expiry:

sudo kubeadm certs check-expiration

---

** PART 3: Static Pods Manifest**

Static pods for control plane live in:

/etc/kubernetes/manifests/

List static pod definitions:

sudo ls -l /etc/kubernetes/manifests/

You should see:

• kube-apiserver.yaml

• kube-controller-manager.yaml

• kube-scheduler.yaml

• etcd.yaml

These YAML files define how each control plane pod runs.

Example: View API Server manifest:

sudo cat /etc/kubernetes/manifests/kube-apiserver.yaml

Look for:

• image version

• cert/key paths

• service port (6443)

** PART 4: Cluster Name & API Server Endpoint**

Get cluster name:

kubectl config view -o jsonpath='{.contexts[?(@.name=="'$(kubectl config current-context)'")].context.cluster}'

Get API Server endpoint:

kubectl cluster-info

This returns:

Kubernetes control plane is running at https://<api-server-ip>:6443

Or from kubeconfig:

kubectl config view --minify -o jsonpath='{.clusters[0].cluster.server}'

** PART 5: Configure Lens to Join the Cluster**

Steps:

1. Open Lens

2. Click Add Cluster

3. Choose “Add from kubeconfig”

4. Lens auto-detects ~/.kube/config

5. Select cluster and press Add

6. Cluster appears on the left panel

7. Click to open and it will prompt for access

8. Cluster Dashboard opens with:

   • Nodes pane

   • Workloads

   • Storage

   • Events

   • Metrics

If your kubeconfig is not in default location:

• Click Browse and upload/custom select the file.

** PART 6: Useful Cluster Metadata Commands**

Get nodes:

kubectl get nodes -o wide

Get API server version:

kubectl version --short

Get cluster info:

kubectl cluster-info

View component statuses (if enabled):

kubectl get componentstatuses

Get namespaces:

kubectl get ns

Get all pods in all namespaces:

kubectl get pods -A

** PART 7: Inspecting Control Plane Pods**

Run these on the master node inside kubelet:

Check control plane pods:

kubectl get pods -n kube-system -o wide

Expected:

• kube-apiserver

• kube-controller-manager

• kube-scheduler

• etcd

• coredns

• network plugin (calico/flannel etc.)

** PART 8: Bonus — Explore API Server Logs**

Get logs:

kubectl -n kube-system logs kube-apiserver-<node-name>

For example:

kubectl -n kube-system logs kube-apiserver-master-node