The Kubernetes Command Line Interface (CLI), known as kubectl, is a powerful tool that allows you to interact with your Kubernetes cluster. It provides commands for deploying applications, inspecting and managing cluster resources, and viewing logs.

• kubectl: The command-line tool for interacting with Kubernetes clusters.
• Commands: Specific instructions you give to kubectl to perform actions on the cluster.
• Resources: Objects in the Kubernetes API that represent the state of your cluster, such as pods, services, and deployments.

To use kubectl, you need to install it on your local machine. Follow these steps to install kubectl:

1. Download the latest release from the Kubernetes release page.
2. Add the binary to your PATH.

1. Use Homebrew to install kubectl:

   brew install kubectl
   

1. Download the latest release with the command:

   curl -LO "https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/linux/amd64/kubectl"
   

2. Make the binary executable:

   chmod +x ./kubectl
   

3. Move the binary to your PATH:

   sudo mv ./kubectl /usr/local/bin/kubectl
   

Here are some basic kubectl commands to get you started:

This command displays information about the Kubernetes cluster.

This command lists all the nodes in the cluster.

This command lists all the pods in the default namespace.

This command provides detailed information about a specific pod.

This command creates a resource from a YAML configuration file.

This command deletes a resource defined in a YAML configuration file.

Let's create a simple deployment using kubectl.

Create a file named nginx-deployment.yaml with the following content:

Use kubectl to create the deployment:

Check the status of the deployment:

You should see the nginx-deployment listed with 3 replicas.

List the pods created by the deployment:

You should see 3 pods running.

1. Create a YAML file named nginx-service.yaml with the following content:

   apiVersion: v1
   kind: Service
   metadata:
     name: nginx-service
   spec:
     selector:
       app: nginx
     ports:
       - protocol: TCP
         port: 80
         targetPort: 80
   

2. Apply the YAML file using kubectl:

   kubectl apply -f nginx-service.yaml
   

3. Verify the service:

   kubectl get services
   

1. Create the nginx-service.yaml file as shown above.
2. Apply the file:

   kubectl apply -f nginx-service.yaml
   

3. Verify the service:

   kubectl get services
   

• Incorrect YAML Syntax: Ensure your YAML files are correctly formatted. Use a YAML validator if necessary.
• Resource Names: Be consistent with naming conventions to avoid confusion.
• Namespace Issues: If you don't specify a namespace, kubectl uses the default namespace. Use the -n flag to specify a different namespace.

In this section, you learned how to install and use kubectl to interact with your Kubernetes cluster. You practiced basic commands and created a deployment and a service using YAML configuration files. Understanding kubectl is essential for managing Kubernetes clusters effectively. In the next module, we will dive deeper into the core components of Kubernetes.