Master Kubernetes Cluster Management: Essential kubectl Commands Explained

1. Viewing

1.1 View cluster status

# View client and server version

<code>kubectl version --short=true</code>

# View cluster information

<code>kubectl cluster-info</code>

1.2 View resource objects

# List namespaces

<code>kubectl get namespace</code>

# List all pods (add

-n <namespace>

for a specific namespace,

-o wide

for details)

<code>kubectl get pod
kubectl get pod -n kube
kubectl get pod -o wide</code>

# Label selector

<code>kubectl get pods -l app=example</code>

# Watch resource changes

<code>kubectl get pod -w</code>

# Output in YAML or JSON

<code>kubectl get pod &lt;pod-name&gt; -o yaml
kubectl get pod &lt;pod-name&gt; -o json</code>

# Common resource types

node (节点)

po (pod)

ns (namespace)

instance (实例)

svc (service)：定义了 Pod 的逻辑分组和访问策略

cm (configMap)：存储全局配置变量

ds (daemonSet)：在每个节点上运行守护进程

deploy (deployment)：管理 Pod 或 ReplicaSet 的部署

ingress：通过 HTTP/HTTPS 暴露 Service，提供外部 URL、负载均衡、SSL/TLS 等

endpoint、pv、pvc 等存储相关资源

1.3 View details

The

describe

command provides detailed information about a resource, especially its current state and events.

<code>kubectl describe pod &lt;Pod Name&gt;
kubectl describe deployment &lt;Deployment Name&gt;
kubectl describe service &lt;Service Name&gt;
kubectl describe node [node ip]
kubectl describe pods &lt;Deployment Name&gt;
kubectl describe pod/{pod_name} -n {namespace}</code>

1.4 View logs

# Real‑time logs

<code>kubectl logs -f &lt;pod_name&gt;</code>

# Specify container if pod has multiple containers

<code>kubectl logs -f &lt;pod_name&gt; -c &lt;container_name&gt;</code>

# Attach to a container (similar to

docker attach

)

<code>kubectl attach &lt;pod_name&gt; -c &lt;container_name&gt;</code>

1.5 View Kubernetes configuration

1.6 Explain resource fields

<code>kubectl explain pod
kubectl explain pod.apiVersion</code>

1.7 View node labels

<code>kubectl get node --show-labels</code>

1.8 File transfer

# Copy files between pod and local machine

<code># Create a file inside the pod
kubectl exec -it mysql-478535978-1dnm2 sh -c "echo 'this is a message from $(hostname)' > /tmp/message.log"
# Copy the file out
kubectl cp mysql-478535978-1dnm2:/tmp/message.log ./message.log
# Modify locally and copy back
echo "information added" >> message.log
kubectl cp ./message.log mysql-478535978-1dnm2:/tmp/message.log</code>

2. Create/Modify Resources

2.1 kubectl create / apply

<code># Create a deployment from command line
kubectl create deployment nginx --image=nginx:1.14
# Create from a manifest file (once)
kubectl create -f my-nginx.yaml
# Apply a manifest (idempotent)
kubectl apply -f my-nginx.yaml</code>

2.2 kubectl replace / patch

Use

replace

to delete and recreate a resource, or

patch

to modify fields in place.

<code># Replace entire resource
kubectl replace -f &lt;yaml_file&gt;
# Patch a pod's label
kubectl patch pod rc-nginx-2-kpiqt -p '{"metadata":{"labels":{"app":"nginx-3"}}}'</code>

2.3 kubectl edit

Opens the resource in an editor for interactive changes.

<code># Edit a pod
kubectl edit po rc-nginx-btv4j</code>

2.4 kubectl set

Set resource limits, requests, or update images.

<code># Set CPU and memory limits for a deployment
kubectl set resources deployment nginx -c=nginx --limits=cpu=200m,memory=512Mi
# Update container image
kubectl set image deployment/nginx nginx=nginx:1.9.1</code>

2.5 kubectl label and annotate

Manage labels and annotations on resources.

<code># Add a label
kubectl label pods foo unhealthy=true
# Overwrite a label
kubectl label --overwrite pods foo status=unhealthy
# Delete a label
kubectl label pods foo bar-
# Add an annotation
kubectl annotate pods foo description='my frontend'</code>

3. Launch Pods

# Create and run a pod from an image

<code>kubectl run nginx --image=nginx:1.16 --port=80 --replicas=1</code>

The command creates a deployment named "nginx" and you can list the resulting pod with:

<code>kubectl get pods</code>