Container Networking in Kubernetes

DevOps Intermediate

Container Networking in Kubernetes¶

KubernetesNetworkingCNIIngress 6 min read

Kubernetes networking model. CNI plugins, Service types, Ingress controllers and DNS.

K8s Network Model¶

Every pod has its own IP address. Basic rules:

• Every pod can communicate with every other pod (without NAT)
• Nodes can communicate with pods (without NAT)
• The IP a pod sees for itself = the IP visible to others

CNI Plugins¶

• Calico — BGP routing, network policies, widely used
• Cilium — eBPF-based, high performance, advanced network policies
• Flannel — simple overlay, suitable for beginners
• Weave — mesh network, encrypted

# Cilium installation
helm install cilium cilium/cilium \
  --namespace kube-system \
  --set hubble.enabled=true \
  --set hubble.relay.enabled=true \
  --set hubble.ui.enabled=true

Service Types¶

# ClusterIP — internal (default)
apiVersion: v1
kind: Service
spec:
  type: ClusterIP
  selector:
    app: api
  ports:
    - port: 80
      targetPort: 8080

# NodePort — access via port on the node
spec:
  type: NodePort
  ports:
    - port: 80
      nodePort: 30080

# LoadBalancer — cloud LB
spec:
  type: LoadBalancer
  ports:
    - port: 443

Ingress¶

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: api-ingress
  annotations:
    cert-manager.io/cluster-issuer: letsencrypt
spec:
  ingressClassName: nginx
  tls:
    - hosts: [api.example.com]
      secretName: api-tls
  rules:
    - host: api.example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: api-server
                port:
                  number: 80

Summary¶

K8s networking is a flat model with pod-to-pod communication. Choose the CNI plugin based on your needs: Cilium for eBPF performance, Calico for network policies.

Need Help with Implementation?¶

Our team has experience designing and implementing modern architectures. We’re happy to help.

Free Consultation