Cilium Has a Free API — eBPF-Powered Networking for Kubernetes

#kubernetes #security #devops #networking

Cilium: Next-Generation Kubernetes Networking

Cilium uses eBPF (extended Berkeley Packet Filter) to provide networking, observability, and security for Kubernetes. It operates at the Linux kernel level — faster than iptables, more powerful than traditional CNI plugins.

Why Cilium Over Traditional CNI

eBPF-based — kernel-level packet processing, no iptables chains
Identity-based security — policies based on pod labels, not IPs
Transparent encryption — WireGuard or IPsec between nodes
Service mesh — built-in L7 load balancing without sidecars
Hubble — deep network observability

The Free API (CRDs + CLI)

# Network policy — L3/L4/L7
apiVersion: cilium.io/v2
kind: CiliumNetworkPolicy
metadata:
  name: api-access
spec:
  endpointSelector:
    matchLabels:
      app: api-server
  ingress:
  - fromEndpoints:
    - matchLabels:
        app: frontend
    toPorts:
    - ports:
      - port: "8080"
        protocol: TCP
      rules:
        http:
        - method: GET
          path: /api/v1/.*

# Cilium CLI
cilium status
cilium connectivity test
cilium hubble port-forward

# Hubble observability
hubble observe --namespace default
hubble observe --verdict DROPPED
hubble observe --protocol http --http-status 500

Hubble: Network Observability

Hubble provides real-time visibility into network flows:

# See all HTTP requests
hubble observe --protocol http -o json | jq .flow.l7.http

# DNS queries
hubble observe --protocol dns

# Dropped packets (security issues)
hubble observe --verdict DROPPED --namespace production

Real-World Use Case

A platform serving 100K RPS replaced Calico with Cilium. Results: 40% lower latency on service-to-service calls, built-in WireGuard encryption (no VPN needed), and Hubble dashboards replaced 3 separate monitoring tools.

Quick Start

cilium install
cilium status --wait
cilium hubble enable --ui
cilium connectivity test

Resources

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