Kubernetets: update Command Doc
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# Kubernetes
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## `kubectl` Command Reference
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### Get State of API Resources
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```bash
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kubectl api-resources
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```
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# Kubernetes Command Reference
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This document provides a reference for common `kubectl` commands used for managing Kubernetes clusters. Use the examples and explanations below to help manage nodes, namespaces, pods, deployments, and more.
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## Table of Contents
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- [Kubernetes Command Reference](#kubernetes-command-reference)
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- [Table of Contents](#table-of-contents)
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- [General Commands](#general-commands)
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- [Node Management](#node-management)
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- [Namespace Management](#namespace-management)
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- [Pod Management](#pod-management)
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- [Listing Pods](#listing-pods)
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- [Running a Pod](#running-a-pod)
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- [Deleting a Pod](#deleting-a-pod)
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- [API Resources and Documentation](#api-resources-and-documentation)
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- [Logs and Pod Information](#logs-and-pod-information)
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- [Applying YAML Files](#applying-yaml-files)
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- [Managing Nodes and Labels](#managing-nodes-and-labels)
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- [Viewing Cluster Resources](#viewing-cluster-resources)
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- [ReplicaSet and Deployment Management](#replicaset-and-deployment-management)
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- [Additional Information](#additional-information)
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---
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## General Commands
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- **List API Resources**
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```bash
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kubectl api-resources
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```
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---
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## Node Management
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- **Show all nodes**
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### Node Management
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- **Show all nodes:**
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```bash
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kubectl get node
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```
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### Namespace Management
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- **List all namespaces:**
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- **Set a label on a node**
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```bash
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kubectl label nodes <node-name> kubernetes.io/<label-key>=<label-value>
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```
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---
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## Namespace Management
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- **List all namespaces**
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```bash
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kubectl get namespaces
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```
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```bash
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# or the abbreviated version:
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kubectl get ns
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```
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- **Create a custom namespace:**
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- **Create a custom namespace**
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```bash
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kubectl create ns <namespace-name>
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```
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### Pod Management
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- **Get the list of pods in the default namespace:**
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---
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## Pod Management
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### Listing Pods
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- **List pods in the default namespace**
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```bash
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kubectl get pod
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```
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- **Get the list of pods in the default namespace with full information:**
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- **List pods with detailed information (wide output) in the default namespace**
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```bash
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kubectl get pod -o wide
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```
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- **Get the list of pods in a custom namespace with full information:**
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- **List pods with detailed information in a specific namespace**
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```bash
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kubectl get pod -o wide -n <name-space>
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kubectl get pod -o wide -n <namespace-name>
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```
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### Running a Pod
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- **Run a new pod:**
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- **Run a new pod**
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Use the following command structure to run a pod with various options:
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```bash
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kubectl run <pod-name> <switch> {
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--image=<image-name>, # Specifies the container image to use
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--port=<portnumber>, # Specifies the port that the container exposes
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-n <namespace-name>, # Specifies the namespace
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--env="KEY=VALUE", # Sets environment variables in the container
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--command, # Treats the rest of the arguments as the command to run in the container
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--replicas=<number>, # Specifies the number of replicas for the deployment
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--labels="key=value,key2=value2", # Adds labels to the pod(s)
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--dry-run=client, # Prints the object that would be sent, without creating it
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--restart=<Always|OnFailure|Never>, # Determines the restart policy for the pod
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--overrides='<json>', # Provides a JSON override for the generated object
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--image-pull-policy=<policy>, # Specifies the image pull policy (Always, IfNotPresent, Never)
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--limits=cpu=<cpu>,memory=<memory>, # Specifies resource limits for the container
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--requests=cpu=<cpu>,memory=<memory> # Specifies resource requests for the container
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}
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kubectl run <pod-name> <switch> {
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--image=<image-name>, # Container image to use
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--port=<port-number>, # Port that the container exposes
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-n <namespace-name>, # Namespace in which to run the pod
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--env="KEY=VALUE", # Environment variables for the container
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--command, # Treat the following arguments as the command
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--replicas=<number>, # Number of pod replicas to create
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--labels="key=value,key2=value2", # Labels to assign to the pod(s)
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--dry-run=client, # Print the object without creating it
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--restart=<Always|OnFailure|Never>, # Pod restart policy
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--overrides='<json>', # JSON override for the generated object
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--image-pull-policy=<policy>, # Image pull policy (Always, IfNotPresent, Never)
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--limits=cpu=<cpu>,memory=<memory>, # Resource limits for the container
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--requests=cpu=<cpu>,memory=<memory> # Resource requests for the container
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}
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```
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- *Example:*
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- **Example:**
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```bash
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kubectl run mypod --image=nginx --port=80 -n mynamespace \
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kubectl run mypod --image=nginx --port=80 -n mynamespace \
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--env="ENV_VAR_NAME=VALUE" --command -- nginx -g "daemon off;" \
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--replicas=3 --labels="app=myapp,env=prod" --dry-run=client \
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--restart=Always --overrides='{"spec": {"containers": [{"name": "nginx", "image": "nginx"}]}}' \
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@@ -69,34 +126,118 @@ kubectl api-resources
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--requests=cpu=50m,memory=128Mi
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```
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### Deleting a Pod
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- **Delete a pod in a custom namespace:**
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- **Delete a pod in a custom namespace**
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```bash
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kubectl delete pod -n <namespace-name> <pod-name>
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```
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### API Resource Documentation
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- **Get documentation of an API resource:**
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---
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## API Resources and Documentation
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- **Get documentation for an API resource**
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```bash
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kubectl explain <api-resource-name>
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```
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- *Example:*
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```bash
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kubectl explain pod
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```
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### Logging and Pod Information
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- **Get and follow logs of a pod (pod must be created and running):**
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---
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## Logs and Pod Information
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- **Stream logs for a running pod**
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```bash
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kubectl logs -f -n <namespace-name> <podname>
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```
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- **Get logs and state information of a pod (works at any time):**
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```bash
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kubectl describe pod -n <namespace-name> <podname>
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kubectl logs -f -n <namespace-name> <pod-name>
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```
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### Apply Yaml File
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```bash
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kubectl apply -f <yaml-file> -n <namespace-name>
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```
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- **Get detailed state and log information for a pod**
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```bash
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kubectl describe pod -n <namespace-name> <pod-name>
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```
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---
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## Applying YAML Files
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- **Apply configuration from a YAML file to a specific namespace**
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```bash
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kubectl apply -f <yaml-file> -n <namespace-name>
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```
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---
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## Managing Nodes and Labels
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- **Label a node with a custom key-value pair**
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```bash
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kubectl label nodes <node-name> kubernetes.io/<label-key>=<label-value>
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```
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---
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## Viewing Cluster Resources
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- **Display all resources loaded in a namespace**
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```bash
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kubectl get all -n <namespace-name>
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```
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- **Display replica sets, pods, and deployments in a specific namespace**
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```bash
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kubectl get rs,pod,deployment -n <namespace-name>
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```
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---
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## ReplicaSet and Deployment Management
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- **Scale a ReplicaSet**
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```bash
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kubectl scale rs <replicaset-name> -n <namespace-name> --replicas=<count>
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```
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- **View rollout history of a deployment**
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```bash
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kubectl rollout history deployment -n <namespace-name> <deployment-name>
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```
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- **View details of a specific revision in a deployment's rollout history**
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```bash
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kubectl rollout history deployment -n <namespace-name> <deployment-name> --revision <number>
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```
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- **Roll back a deployment to a specific revision**
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```bash
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kubectl rollout undo deployment -n <namespace-name> <deployment-name> --to-revision=<number>
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```
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> **Note:** The command for rolling back to a specific revision is `kubectl rollout undo` rather than using `--to-revision` with `kubectl rollout history`.
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---
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## Additional Information
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- **Static Manifest Files**
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All YAML files located under `/etc/kubernetes/manifests/` are automatically loaded after a server reboot.
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---
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