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Kubernetes Cheat Sheet: Essential Commands for Beginners

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Kubernetes Cheat Sheet: Essential Commands for Beginners

Kubernetes, often referred to as K8s, is an open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications. It's a powerful tool for building and deploying microservices-based applications, ensuring high availability, and simplifying the management of complex infrastructure.

This cheat sheet provides a collection of essential Kubernetes commands for beginners to get started with K8s. We'll cover the basics, including creating deployments, services, pods, and namespaces, along with some useful utilities for troubleshooting and managing your applications.

Getting Started

Install Kubernetes

You can install Kubernetes on your local machine, in a cloud environment, or using a managed Kubernetes service. Here are some popular options:

Minikube: A single-node Kubernetes cluster for local development (recommended for beginners). https://kubernetes.io/docs/setup/learning-environment/minikube/
Docker Desktop: Includes a built-in Kubernetes cluster for Windows and macOS. https://www.docker.com/products/docker-desktop/
Cloud Providers: AWS EKS, Azure AKS, Google Kubernetes Engine (GKE). Each provider offers a managed Kubernetes service with varying levels of support and features.

Access Your Kubernetes Cluster

After installing, you need to configure your local machine to access the Kubernetes cluster. This involves setting up kubectl, the command-line tool for interacting with your cluster.

Using kubectl:

kubectl version

This command will display the version of kubectl and the server version of your Kubernetes cluster.

Core Kubernetes Concepts

Understanding these core concepts is crucial for effective Kubernetes management:

Pods

The smallest deployable unit in Kubernetes. A Pod is a group of one or more containers, sharing the same resources and network namespace.

Deployments

A Kubernetes Deployment is used to manage and update your applications. It defines the desired state of your application, including the number of replicas, the image to use, and the container resources.

Services

Services provide a consistent way to access your Pods. They abstract away the specific Pods running your application, providing a stable network endpoint. Services can be accessed using DNS names or IP addresses.

Namespaces

Namespaces provide a way to logically organize your Kubernetes resources. They are useful for separating resources for different teams, applications, or environments.

Controllers

Controllers are responsible for managing the desired state of your application. They ensure that the desired number of Pods are running and that they are healthy. Common controllers include Deployments, StatefulSets, and DaemonSets.

Ingress

Ingress provides a way to route external traffic to your services. It acts as a reverse proxy, handling incoming HTTP requests and directing them to the appropriate service.

Essential Kubernetes Commands

Creating and Managing Deployments

Deployments are used to define the desired state of your application and manage updates.

# Create a Deployment named 'nginx-deployment' with 3 replicas running the 'nginx' image
kubectl create deployment nginx-deployment --image=nginx --replicas=3

Check the status of the Deployment

kubectl get deployment nginx-deployment

Scale the Deployment to 5 replicas

kubectl scale deployment nginx-deployment --replicas=5

Update the Deployment with a new image

kubectl set image deployment nginx-deployment nginx=nginx:latest

Creating and Managing Services

Services provide a way to access your Pods and abstract away the specific Pods running your application.

Create a Service named 'nginx-service' of type 'LoadBalancer' that exposes port 80 on the Pod to port 80 on the service

kubectl create service LoadBalancer nginx-service --port=80 --target-port=80 --selector=app=nginx

Get the external IP address of the service

kubectl get service nginx-service -o wide

Delete the service

kubectl delete service nginx-service

Listing Resources

Use these commands to get an overview of your Kubernetes resources.

List all Pods

kubectl get pods

List all Deployments

kubectl get deployments

List all Services

kubectl get services

List all Namespaces

kubectl get namespaces

List all nodes

kubectl get nodes

Get the status of a specific pod (replace 'nginx-pod' with the actual pod name)

kubectl get pod nginx-pod -o wide

Managing Pods

These commands allow you to work directly with Pods.

Get logs from a specific pod

kubectl logs nginx-pod

Describe the details of a specific pod

kubectl describe pod nginx-pod

Delete a specific pod

kubectl delete pod nginx-pod

Execute a command within a pod

kubectl exec -it nginx-pod -- bash

Copy files into a pod

kubectl cp /path/to/local/file nginx-pod:/path/in/pod

Working with Namespaces

Use namespaces to logically organize your Kubernetes resources.


  
  
  Create a new namespace


kubectl create namespace my-namespace


  
  
  List namespaces


kubectl get namespaces


  
  
  Set the current namespace


kubectl config set-context --current --namespace=my-namespace


  
  
  Delete a namespace (this will delete all resources within the namespace)


kubectl delete namespace my-namespace

Advanced Operations

# Apply a configuration file (yaml or json) to your cluster kubectl apply -f deployment.yaml

Rollback a Deployment to a previous revision

kubectl rollout undo deployment nginx-deployment

View events for a specific resource

kubectl get events --field-selector involvedObject.kind=Deployment,involvedObject.name=nginx-deployment

Get resource usage for a specific pod

kubectl top pod nginx-pod

Troubleshooting

When things go wrong, you'll need to diagnose and resolve issues. Here are some helpful commands:

Get logs from a specific pod

kubectl logs nginx-pod

Describe the details of a specific pod

kubectl describe pod nginx-pod

Check for events related to a resource

kubectl get events --field-selector involvedObject.kind=Deployment,involvedObject.name=nginx-deployment

View the status of the kubelet process on a node

kubectl get nodes --field-selector spec.nodeName=your-node-name

Get the status of the Kubernetes control plane

kubectl get componentstatuses

Best Practices

Here are some best practices for working with Kubernetes:

Use Namespaces:

Organize your resources for better management and security.
Define Resource Limits:

Limit resource usage for each container to prevent resource starvation.
Use Health Checks:

Ensure your application is healthy and restarts automatically if it fails.
Use Persistent Volumes:

Store data persistently for your applications.
Automate Deployments:

Use tools like Helm or Kustomize to manage and automate deployments.
Monitor and Log:

Implement monitoring and logging solutions to gain insights into your applications and infrastructure.

Conclusion

This cheat sheet provided a foundation of essential Kubernetes commands and concepts for beginners. By familiarizing yourself with these commands and understanding the underlying concepts, you can start deploying and managing containerized applications in Kubernetes. Remember to practice, explore documentation, and utilize community resources to further your Kubernetes journey.