kubernates(K8s) resources Overview with examples with explanation

Category : Kubernetes | Sub Category : Kubernetes With Java | By Prasad Bonam Last updated: 2023-11-17 08:23:58 Viewed : 143


1. Pod:

A Pod is the smallest deployable unit in Kubernetes, representing a single instance of a running process. It can contain one or more containers.

yaml
apiVersion: v1 kind: Pod metadata: name: example-pod spec: containers: - name: nginx-container image: nginx

Explanation:

  • This YAML file defines a basic Pod named "example-pod."
  • It contains a single container named "nginx-container," which runs the Nginx image.

2. Service:

A Service exposes a set of Pods as a network service. It allows other applications to discover and communicate with the Pods.

yaml
apiVersion: v1 kind: Service metadata: name: example-service spec: selector: app: example-app ports: - protocol: TCP port: 80 targetPort: 8080

Explanation:

  • This YAML file creates a Service named "example-service."
  • It selects Pods with the label "app: example-app" and exposes them on port 80, forwarding traffic to port 8080 in the selected Pods.

3. Namespace:

A Namespace provides a way to divide cluster resources between multiple users or teams.

yaml
apiVersion: v1 kind: Namespace metadata: name: example-namespace

Explanation:

  • This YAML file creates a Namespace named "example-namespace."

4. Deployment:

A Deployment manages the deployment and scaling of Pods, allowing declarative updates to applications.

yaml
apiVersion: apps/v1 kind: Deployment metadata: name: example-deployment spec: replicas: 3 selector: matchLabels: app: example-app template: metadata: labels: app: example-app spec: containers: - name: nginx-container image: nginx

Explanation:

  • This YAML file creates a Deployment named "example-deployment."
  • It ensures there are three replicas of Pods with the label "app: example-app," each running the Nginx container.

5. ReplicaSet:

A ReplicaSet ensures a specified number of replicas of a Pod are running.

yaml
apiVersion: apps/v1 kind: ReplicaSet metadata: name: example-replicaset spec: replicas: 2 selector: matchLabels: app: example-app template: metadata: labels: app: example-app spec: containers: - name: nginx-container image: nginx

Explanation:

  • This YAML file creates a ReplicaSet named "example-replicaset."
  • It ensures there are two replicas of Pods with the label "app: example-app," each running the Nginx container.

6. ConfigMap:

A ConfigMap allows you to decouple configuration artifacts from the container image.

yaml
apiVersion: v1 kind: ConfigMap metadata: name: example-configmap data: key1: value1 key2: value2

Explanation:

  • This YAML file creates a ConfigMap named "example-configmap."
  • It defines key-value pairs (key1: value1, key2: value2) that can be used as configuration data in Pods.

7. Secret:

A Secret stores sensitive information, such as passwords or API keys, in a Base64-encoded format.

yaml
apiVersion: v1 kind: Secret metadata: name: example-secret type: Opaque data: username: <base64-encoded-username> password: <base64-encoded-password>

Explanation:

  • This YAML file creates a Secret named "example-secret" with a username and password encoded in Base64 format.

8. Volume:

A Volume is a directory that is accessible to containers in a Pod, providing a way to persist data.

yaml
apiVersion: v1 kind: Pod metadata: name: example-pod spec: containers: - name: nginx-container image: nginx volumeMounts: - name: example-volume mountPath: /usr/share/nginx/html volumes: - name: example-volume emptyDir: {}

Explanation:

  • This YAML file defines a Pod with an Nginx container and an emptyDir Volume mounted at "/usr/share/nginx/html."

9. Ingress:

An Ingress provides HTTP and HTTPS routing to services based on rules, enabling external access to services in a cluster.

yaml
apiVersion: networking.k8s.io/v1 kind: Ingress metadata: name: example-ingress spec: rules: - host: example.com http: paths: - path: / pathType: Prefix backend: service: name: example-service port: number: 80

Explanation:

  • This YAML file creates an Ingress named "example-ingress."
  • It defines a rule for routing HTTP traffic from "example.com" to the Service named "example-service" on port 80.

These examples cover some of the fundamental Kubernetes resources and how they are configured. You can customize these examples based on your specific application requirements.


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