my-docs/Containerization & Orchestration/Kubernetes/workloads/10-Deployment-With-Services.md

1st Document: Namespace

apiVersion: v1

• Specifies the API version used. Here, it's version 1 of the core Kubernetes API.

kind: Namespace

• Declares the resource type. This is a Namespace, which logically isolates groups of resources.

metadata:
  name: ns

• Metadata block.

  • name: ns sets the name of the namespace to ns.

---

2nd Document: Service

---

• Separates multiple documents in the YAML file.

apiVersion: v1

• Uses the core v1 API again.

kind: Service

• Declares a Service resource, which provides stable networking to access pods.

metadata:
  name: nginx-service
  namespace: ns
  labels:
    app: nginx

• Metadata block:

  • name: nginx-service: name of the Service.
  • namespace: ns: places this service in the previously created ns namespace.
  • labels: key-value pairs used for organizing and selecting resources. Here, app: nginx.

spec:
  type: ClusterIP

• spec describes the behavior.

  • type: ClusterIP: exposes the service internally within the cluster using a virtual IP.

  selector:
    app: nginx

• This selects pods with the label app: nginx to receive traffic from this service.

  ports:
    - name: http
      port: 80
      targetPort: 8080

• Defines port configuration:

  • name: http: a name for the port (optional but useful for readability).
  • port: 80: the port that the service exposes internally.
  • targetPort: 8080: the port on the pod that receives the traffic.

---

3rd Document: Deployment

---

• Separates from the previous document.

apiVersion: apps/v1

• Uses the apps/v1 API group, suitable for deployments and other controllers.

kind: Deployment

• Declares a Deployment, which ensures a specified number of pod replicas are running.

metadata:
  name: nginx-deployment
  namespace: ns
  labels:
    app: nginx

• Metadata block:

  • name: nginx-deployment: name of the deployment.
  • namespace: ns: places this in the ns namespace.
  • labels: app: nginx: used for matching with selectors.

spec:
  replicas: 2

• Desired number of pod replicas to run: 2.

  selector:
    matchLabels:
      app: nginx

• Tells the deployment which pods to manage, by matching labels (app: nginx).

  template:
    metadata:
      labels:
        app: nginx

• Template for creating new pods:

  • Each pod created will have app: nginx label.

    spec:
      containers:
        - name: nginx
          image: nginx:latest

• Pod spec:

  • One container named nginx, using the latest official Nginx image.

          ports:
            - containerPort: 8080

• The container exposes port 8080 (must match the targetPort in the Service).

          resources:
            requests:
              cpu: "100m"
              memory: "128Mi"
            limits:
              cpu: "250m"
              memory: "256Mi"

• Resource management:

  • requests: the minimum guaranteed resources.

    • cpu: 100m = 0.1 CPU core.
    • memory: 128Mi = 128 MiB RAM.

  • limits: the maximum resources the container can use.

    • cpu: 250m = 0.25 CPU core.
    • memory: 256Mi = 256 MiB RAM.