Cilium 1.18: Advanced Networking and Security for Cloud-Native Deployments

Introduction

With CNI stacks, “it’s fine” usually means “it’s fine until it isn’t”: a burst of connections, an unexpected policy interaction, or a multi-cluster edge case that only shows up under real traffic.

Cilium 1.18, released on July 29, 2025, continues the eBPF networking trajectory with upgrades in observability (Hubble), security (policy, identity, encryption), and performance—plus continued investment in Gateway API and multi-cluster networking.

Why this matters in practice

• Better day-2 debugging: improved flow visibility helps answer “is this policy, routing, or the app?” faster.
• Security posture as code: identity-based policy and encryption improvements reduce the gap between intent and enforcement.
• Scale and multi-cluster: cluster-mesh and conntrack work matters when you’re operating beyond a single cluster boundary.
• Gateway API maturity: fewer footguns when standardizing north-south routing on Gateway API resources.

Advanced Observability

• Enhanced Hubble delivers deeper insights into network flows, security events, and application behavior with improved filtering and analysis capabilities.
• Service dependency mapping provides comprehensive visualization of service interactions and dependencies across microservices architectures.
• Performance metrics expansion exposes detailed network performance metrics for better troubleshooting and optimization.
• Event correlation enables connecting security events, network flows, and application logs for comprehensive analysis.

Security Enhancements

1. Network policy improvements provide more granular and expressive security policies with better performance.
2. Threat detection introduces advanced threat detection capabilities through machine learning-enhanced analysis.
3. Encryption enhancements improve WireGuard integration with automatic key rotation and better performance characteristics.
4. Identity-based security strengthens zero-trust networking with refined identity resolution and policy enforcement.

Performance Optimizations

• eBPF program efficiency optimizes eBPF programs for reduced CPU overhead and improved throughput.
• Connection tracking enhancements improve scalability for high-connection workloads with better memory utilization.
• Load balancing improvements deliver more efficient load distribution algorithms with lower latency.
• Service mesh acceleration further improves service mesh performance by eliminating additional overhead.

Gateway API Enhancements

• Extended Gateway API support provides comprehensive support for Gateway API v1 features with production-ready implementations.
• Multi-protocol routing enables sophisticated routing for HTTP, HTTPS, gRPC, and WebSocket protocols.
• Traffic management delivers advanced traffic splitting, mirroring, and rate limiting capabilities.
• TLS management enhances automatic certificate management with support for multiple certificate providers.

Multi-Cluster Networking

1. Cluster mesh improvements enhance connectivity and service discovery across multiple Kubernetes clusters.
2. Global services enable services to be accessed across cluster boundaries with transparent routing.
3. Network policy synchronization provides consistent security policies across multi-cluster deployments.
4. Observability expansion delivers unified observability across cluster boundaries for comprehensive visibility.

Getting Started

helm repo add cilium https://helm.cilium.io/
helm repo update

helm install cilium cilium/cilium --version 1.18.0 \
  --namespace kube-system \
  --set hubble.enabled=true \
  --set hubble.relay.enabled=true \
  --set hubble.ui.enabled=true \
  --set gatewayAPI.enabled=true \
  --set operator.replicas=2 \
  --set clusterMesh.enabled=true

Upgrade from previous version:

# Backup current configuration
kubectl get configmap cilium-config -n kube-system -o yaml > cilium-config-backup.yaml

# Upgrade using Helm
helm upgrade cilium cilium/cilium \
  --version 1.18.0 \
  --namespace kube-system \
  --reuse-values

# Verify installation and connectivity
cilium status --wait
cilium connectivity test
cilium clustermesh status

Advanced Configuration Example

Multi-cluster mesh configuration:

apiVersion: v1
kind: ConfigMap
metadata:
  name: cilium-config
  namespace: kube-system
data:
  cluster-name: "production-east"
  cluster-id: "1"
  clustermesh-config: "/var/lib/cilium/clustermesh/"
  enable-hubble: "true"
  enable-remote-node-identity: "true"
  enable-endpoint-health-checking: "true"
  enable-health-check-nodeport: "true"

Gateway API with advanced routing:

apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: api-gateway
spec:
  gatewayClassName: cilium
  listeners:
  - name: https
    protocol: HTTPS
    port: 443
    hostname: "api.example.com"
    tls:
      mode: Terminate
      certificateRefs:
      - name: api-tls-cert
---
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: api-routes
spec:
  parentRefs:
  - name: api-gateway
  hostnames:
  - "api.example.com"
  rules:
  - matches:
    - path:
        type: PathPrefix
        value: /v1
    backendRefs:
    - name: api-v1-service
      port: 8080
      weight: 80
    - name: api-v2-service
      port: 8080
      weight: 20
    filters:
    - type: RequestMirror
      requestMirror:
        backendRef:
          name: api-mirror-service
          port: 8080

Summary

Cilium 1.18 represents continued innovation in eBPF-powered networking, providing Kubernetes teams with the tools needed to build secure, observable, and high-performance cloud-native infrastructure at scale.