====== Kubernetes kubectl Commands Guide ======

This guide covers the most commonly used Kubernetes commands, explanations, and examples.

===== Cheat Sheet =====

^ Category ^ Command ^ Purpose ^
| Cluster | `kubectl cluster-info` | Show cluster information |
| Cluster | `kubectl version` | Show client/server versions |
| Namespace | `kubectl get ns` | List namespaces |
| Namespace | `kubectl create ns <name>` | Create namespace |
| Namespace | `kubectl delete ns <name>` | Delete namespace |
| Resources | `kubectl get pods` | List pods |
| Resources | `kubectl get deployments` | List deployments |
| Resources | `kubectl get svc` | List services |
| Resources | `kubectl get nodes` | List nodes |
| Resources | `kubectl get all` | List common resources |
| Details | `kubectl describe pod <pod>` | Detailed pod information |
| Details | `kubectl describe deployment <name>` | Deployment details |
| Details | `kubectl describe node <node>` | Node details |
| Create | `kubectl apply -f file.yaml` | Create/update resources |
| Create | `kubectl create deployment ...` | Create deployment quickly |
| Update | `kubectl edit deployment <name>` | Edit deployment |
| Update | `kubectl scale deployment <name> --replicas=N` | Scale deployment |
| Update | `kubectl set image ...` | Update container image |
| Delete | `kubectl delete pod <pod>` | Delete pod |
| Delete | `kubectl delete deployment <name>` | Delete deployment |
| Delete | `kubectl delete service <name>` | Delete service |
| Logs | `kubectl logs <pod>` | Show logs |
| Logs | `kubectl logs -f <pod>` | Stream logs |
| Logs | `kubectl logs --previous <pod>` | Show previous container logs |
| Exec | `kubectl exec -it <pod> -- bash` | Open shell inside container |
| Network | `kubectl port-forward pod/<pod> 8080:80` | Forward local port |
| Files | `kubectl cp file.txt pod:/tmp/` | Copy file to pod |
| Files | `kubectl cp pod:/tmp/file.txt .` | Copy file from pod |
| Rollout | `kubectl rollout status deployment/<name>` | Check rollout status |
| Rollout | `kubectl rollout history deployment/<name>` | Show rollout history |
| Rollout | `kubectl rollout undo deployment/<name>` | Rollback deployment |
| Config | `kubectl config get-contexts` | List contexts |
| Config | `kubectl config use-context <ctx>` | Switch context |
| Debug | `kubectl top pod` | Show pod CPU/memory |
| Debug | `kubectl top node` | Show node CPU/memory |

===== Cluster Commands =====

==== Show Cluster Information ====

<code bash>
kubectl cluster-info
</code>

Displays API server and cluster services.

Example:

<code bash>
kubectl cluster-info
</code>

----

==== Show Kubernetes Version ====

<code bash>
kubectl version
</code>

Example:

<code bash>
kubectl version --short
</code>

Output:

<code>
Client Version: v1.34.0
Server Version: v1.34.0
</code>

===== Namespace Commands =====

==== List Namespaces ====

<code bash>
kubectl get namespaces
</code>

Short form:

<code bash>
kubectl get ns
</code>

----

==== Create Namespace ====

<code bash>
kubectl create namespace dev
</code>

----

==== Delete Namespace ====

<code bash>
kubectl delete namespace dev
</code>

===== Viewing Resources =====

==== List Pods ====

<code bash>
kubectl get pods
</code>

----

==== List Pods in All Namespaces ====

<code bash>
kubectl get pods -A
</code>

----

==== List Deployments ====

<code bash>
kubectl get deployments
</code>

----

==== List Services ====

<code bash>
kubectl get svc
</code>

----

==== List Nodes ====

<code bash>
kubectl get nodes
</code>

----

==== Show All Common Resources ====

<code bash>
kubectl get all
</code>

Displays:

  * Pods
  * Deployments
  * ReplicaSets
  * Services

===== Describe Resources =====

==== Describe Pod ====

<code bash>
kubectl describe pod nginx
</code>

Useful for:

  * Events
  * Container status
  * Volumes
  * Environment variables
  * Scheduling issues

----

==== Describe Deployment ====

<code bash>
kubectl describe deployment nginx
</code>

----

==== Describe Node ====

<code bash>
kubectl describe node worker-1
</code>

Shows:

  * CPU
  * Memory
  * Conditions
  * Allocated resources

===== Creating Resources =====

==== Apply YAML File ====

<code bash>
kubectl apply -f deployment.yaml
</code>

Most common Kubernetes command.

Example:

<code bash>
kubectl apply -f nginx-deployment.yaml
</code>

----

==== Apply Entire Directory ====

<code bash>
kubectl apply -f manifests/
</code>

----

==== Create Deployment Quickly ====

<code bash>
kubectl create deployment nginx --image=nginx
</code>

===== Updating Resources =====

==== Edit Resource ====

<code bash>
kubectl edit deployment nginx
</code>

----

==== Scale Deployment ====

<code bash>
kubectl scale deployment nginx --replicas=5
</code>

----

==== Update Container Image ====

<code bash>
kubectl set image deployment/nginx nginx=nginx:1.27
</code>

===== Deleting Resources =====

==== Delete Pod ====

<code bash>
kubectl delete pod nginx
</code>

----

==== Delete Deployment ====

<code bash>
kubectl delete deployment nginx
</code>

----

==== Delete Service ====

<code bash>
kubectl delete service nginx
</code>

----

==== Delete Resources from YAML ====

<code bash>
kubectl delete -f deployment.yaml
</code>

===== Logs =====

==== Show Logs ====

<code bash>
kubectl logs nginx
</code>

----

==== Stream Logs ====

<code bash>
kubectl logs -f nginx
</code>

Equivalent to:

<code bash>
tail -f
</code>

----

==== Logs from Specific Container ====

<code bash>
kubectl logs nginx -c app
</code>

----

==== Previous Container Logs ====

<code bash>
kubectl logs nginx --previous
</code>

Useful when troubleshooting:

  * CrashLoopBackOff
  * Container restart failures

===== Execute Commands Inside Container =====

==== Run One Command ====

<code bash>
kubectl exec nginx -- ls
</code>

----

==== Open Interactive Shell ====

<code bash>
kubectl exec -it nginx -- bash
</code>

or

<code bash>
kubectl exec -it nginx -- sh
</code>

===== Port Forwarding =====

==== Forward Pod Port ====

<code bash>
kubectl port-forward pod/nginx 8080:80
</code>

Access application:

<code>
http://localhost:8080
</code>

----

==== Forward Deployment Port ====

<code bash>
kubectl port-forward deployment/nginx 8080:80
</code>

===== Copy Files =====

==== Copy File To Pod ====

<code bash>
kubectl cp test.txt nginx:/tmp/test.txt
</code>

----

==== Copy File From Pod ====

<code bash>
kubectl cp nginx:/tmp/log.txt .
</code>

===== Rollout Management =====

==== Check Rollout Status ====

<code bash>
kubectl rollout status deployment/nginx
</code>

----

==== View Rollout History ====

<code bash>
kubectl rollout history deployment/nginx
</code>

----

==== Rollback Deployment ====

<code bash>
kubectl rollout undo deployment/nginx
</code>

===== Context Management =====

==== Show Contexts ====

<code bash>
kubectl config get-contexts
</code>

----

==== Show Current Context ====

<code bash>
kubectl config current-context
</code>

----

==== Switch Context ====

<code bash>
kubectl config use-context production
</code>

===== Resource Usage =====

==== Show Pod CPU and Memory ====

<code bash>
kubectl top pod
</code>

----

==== Show Node CPU and Memory ====

<code bash>
kubectl top node
</code>

===== Troubleshooting Workflow =====

When an application is not working:

<code bash>
kubectl get pods
kubectl describe pod <pod-name>
kubectl logs <pod-name>
kubectl exec -it <pod-name> -- sh
kubectl get events --sort-by=.metadata.creationTimestamp
</code>

Typical troubleshooting order:

  - Check pod status
  - Check events
  - Check logs
  - Enter container
  - Verify network/service configuration