Kubernetes Create Command

Introduction

The kubectl create command is used to create Kubernetes resources. It takes a resource definition file as input and creates the resource in the Kubernetes cluster. The resource definition file can be in YAML or JSON format. In this lab, we will be using YAML format.

Skills Graph

Create a Namespace

The first step is to create a namespace. A namespace is a way to divide cluster resources between multiple users. To create a namespace, create a file called namespace.yaml with the following contents:

apiVersion: v1
kind: Namespace
metadata:
  name: mynamespace

Then, run the following command to create the namespace:

kubectl create -f namespace.yaml

This will create a namespace called mynamespace. You can verify that the namespace was created by running the following command:

kubectl get namespaces

This will display a list of namespaces, including the mynamespace namespace.

Create a Deployment

The next step is to create a deployment. A deployment manages a set of replicas of a pod template. To create a deployment, create a file called deployment.yaml with the following contents:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mydeployment
  namespace: mynamespace
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
        - name: mycontainer
          image: nginx

Then, run the following command to create the deployment:

kubectl create -f deployment.yaml

This will create a deployment called mydeployment in the mynamespace namespace. The deployment will manage 3 replicas of a pod template that runs an Nginx container.

You can verify that the deployment was created by running the following command:

kubectl get deployments -n mynamespace

This will display a list of deployments, including the mydeployment deployment.

Create a Service

The next step is to create a service. A service is an abstract way to expose an application running on a set of pods as a network service. To create a service, create a file called service.yaml with the following contents:

apiVersion: v1
kind: Service
metadata:
  name: myservice
  namespace: mynamespace
spec:
  selector:
    app: myapp
  ports:
    - name: http
      port: 80
      targetPort: 80

Then, run the following command to create the service:

kubectl create -f service.yaml

This will create a service called myservice in the mynamespace namespace. The service will select pods with the label app=myapp and expose port 80.

You can verify that the service was created by running the following command:

kubectl get services -n mynamespace

This will display a list of services, including the myservice service.

Create a Secret

The next step is to create a secret. A secret is an object that contains sensitive data, such as passwords or API keys. To create a secret, create a file called secret.yaml with the following contents:

apiVersion: v1
kind: Secret
metadata:
  name: mysecret
  namespace: mynamespace
type: Opaque
data:
  username: dXNlcm5hbWU=
  password: cGFzc3dvcmQ=

In this example, we are creating a secret called mysecret in the mynamespace namespace. The secret contains a username and password encoded in Base64 format.

To create the secret, run the following command:

kubectl create -f secret.yaml

You can verify that the secret was created by running the following command:

kubectl get secrets -n mynamespace

This will display a list of secrets, including the mysecret secret.

Create a Configmap

The final step is to create a configMap. A configMap is an object that contains configuration data that can be consumed by pods. To create a configMap, create a file called configmap.yaml with the following contents:

apiVersion: v1
kind: ConfigMap
metadata:
  name: myconfigmap
  namespace: mynamespace
data:
  config: |
    database.host=example.com
    database.port=5432
    database.user=myuser
    database.password=mypassword

In this example, we are creating a configMap called myconfigmap in the mynamespace namespace. The configMap contains a configuration file that can be consumed by pods.

To create the configMap, run the following command:

kubectl create -f configmap.yaml

You can verify that the configMap was created by running the following command:

kubectl get configmaps -n mynamespace

This will display a list of configMaps, including the myconfigmap configMap.

Summary

Congratulations! In this lab, you learned how to use the kubectl create command to create various Kubernetes resources. You started with simple examples and gradually moved on to more complex examples, including creating a namespace, deployment, service, secret, and configMap. Now you have a good understanding of how to use the kubectl create command to create Kubernetes resources.