Understanding the Kubernetes API with examples

Category : Kubernetes | Sub Category : Learn Kubernetes | By Prasad Bonam Last updated: 2023-11-22 07:28:20 Viewed : 216

Lets go through some practical examples of using the Kubernetes API with the kubectl command-line tool. Note that these examples assume you have kubectl configured to connect to a Kubernetes cluster.

1. List Pods:

   • Use the following command to list all the pods in the default namespace:

     bashCopy code
     kubectl get pods
     

2. Describe a Pod:

   • Get detailed information about a specific pod, including its configuration and events:

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     kubectl describe pod <pod-name>
     

3. Create a Pod:

   • Create a simple pod using a YAML definition. Save the following content in a file named my-pod.yaml and then apply it:

     yamlCopy code
     apiVersion: v1
     kind: Pod
     metadata:
       name: my-pod
     spec:
       containers:
       - name: my-container
         image: nginx
     

     Apply the configuration:

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     kubectl apply -f my-pod.yaml
     

4. Update a Pod:

   • Modify the pod definition and apply the changes:

     yamlCopy code
     apiVersion: v1
     kind: Pod
     metadata:
       name: my-pod
     spec:
       containers:
       - name: my-container
         image: nginx:latest
     

     Apply the changes:

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     kubectl apply -f my-pod.yaml
     

5. Delete a Pod:

   • Delete a pod using its name:

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     kubectl delete pod <pod-name>
     

6. List Services:

   • List all the services in the default namespace:

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     kubectl get services
     

7. Expose a Deployment:

   • Create a simple deployment and expose it as a service:

     yamlCopy code
     apiVersion: apps/v1
     kind: Deployment
     metadata:
       name: my-deployment
     spec:
       replicas: 3
       selector:
         matchLabels:
           app: nginx
       template:
         metadata:
           labels:
             app: nginx
         spec:
           containers:
           - name: nginx
             image: nginx:latest
     ---
     apiVersion: v1
     kind: Service
     metadata:
       name: my-service
     spec:
       selector:
         app: nginx
       ports:
       - protocol: TCP
         port: 80
         targetPort: 80
     

     Apply the configuration:

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     kubectl apply -f my-deployment.yaml
     

8. Scale a Deployment:

   • Scale the deployment to 5 replicas:

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     kubectl scale deployment my-deployment --replicas=5
     

9. Rolling Update:

   • Perform a rolling update of a deployment with a new image:

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     kubectl set image deployment/my-deployment nginx=nginx:1.17 --record
     

10. Namespace Operations:

    • Create a new namespace:

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      kubectl create namespace my-namespace
      

    • List pods in a specific namespace:

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      kubectl get pods --namespace=my-namespace
      

These examples demonstrate basic operations using the Kubernetes API with kubectl. You can adapt and extend these commands for more complex scenarios and configurations as needed. Understanding these operations is crucial for managing and deploying applications on a Kubernetes cluster.