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Networking Basics

1. Introduction to Networking in Kubernetes​

Networking in Kubernetes is a vast area, covering how pods communicate with each other and how external services access applications running in the cluster. This guide provides an overview of these concepts.

2. Understanding Pod Networking​

  • Pod-to-Pod Communication: Each Pod in Kubernetes is assigned a unique IP address within the cluster, allowing them to communicate with each other.
  • Networking Model: Explanation of the Kubernetes networking model, where Pods can communicate with all other Pods without NAT.

3. Services and Their Role​

  • Purpose of Services: Services in Kubernetes provide a way to expose an application running on a set of Pods as a network service.
  • Types of Services: Overview of different types of Services (ClusterIP, NodePort, LoadBalancer) and their use cases.

4. Exposing Applications with Services​

  • Creating a Service:
    • Example YAML configuration for a ClusterIP Service: 
      apiVersion: v1
      kind: Service
      metadata:
        name: my-service
      spec:
        selector:
          app: MyApp
        ports:
          - protocol: TCP
            port: 80
            targetPort: 9376
  • Accessing Services: How to access services within and outside the cluster.

5. Ingress and Ingress Controllers​

  • Ingress Overview: Ingress is a Kubernetes object that manages external access to services in a cluster, typically HTTP.
  • Setting Up Ingress: Basic configuration of Ingress for routing external requests to the correct services.
    • Example Ingress YAML: 
      apiVersion: networking.k8s.io/v1
      kind: Ingress
      metadata:
        name: example-ingress
      spec:
        rules:
        - host: myapp.example.com
          http:
            paths:
            - path: /
              pathType: Prefix
              backend:
                service:
                  name: my-service
                  port:
                    number: 80

6. Network Policies​

  • Introduction to Network Policies: Network policies in Kubernetes allow you to specify how groups of pods are allowed to communicate with each other and other network endpoints.
  • Implementing Network Policies: Basic examples and use cases for applying network policies.