Cilium vs Istio

Cilium is an open-source, cloud-native system for providing, securing, and observing network connectivity between workloads using eBPF. Its networking capabilities include CNI, Layer 4 load balancing, Cluster Mesh, kube-proxy replacement, BGP, service mesh, Gateway API, IPv6, host firewall, and ingress. Network policies can enforce identity-aware rules from L3 through L7, including DNS- and HTTP-aware filtering. Security features include runtime protection and transparent encryption of managed host and endpoint traffic using IPsec, WireGuard, or ztunnel; ztunnel support is marked beta. For visibility, Cilium lists service maps, metrics and tracing export, network flow logs, and protocol visibility. Hubble, built on Cilium and eBPF, provides visibility into service communication and behavior. Documentation describes Prometheus and Grafana integrations and Kubernetes support for services including GKE, AKS, EKS, OpenShift, RKE, k3s, and Alibaba ACK. Its container image requires AMD64 or AArch64 hosts running Linux kernel 5.10 or later, or an equivalent kernel such as 4.18 on RHEL 8.10. For environments above 500 nodes, the quick installation guide directs readers to large-environment guidance or specific datapath modes.

Istio is a free, open-source service mesh that adds security, connectivity, and monitoring for distributed applications with few or no service-code changes. It manages HTTP, gRPC, WebSocket, and TCP traffic, with automatic load balancing, routing rules, retries, failovers, and fault injection. Deployment options include sidecar mode and ambient mode, which uses a per-node Layer 4 proxy and can optionally add a per-namespace Envoy proxy for Layer 7 features. The control plane runs on Kubernetes, while the mesh can extend to other clusters, virtual machines, and endpoints outside Kubernetes. Security capabilities include workload identity, mutual TLS, authentication, authorization policies, and audit tools. Istio can generate traffic metrics, logs, and traces, including for ingress and egress. It can be installed with istioctl or Helm, and its integrations documentation covers tools such as Prometheus, Grafana, Jaeger, Kiali, and cert-manager. Istio 1.31 supports Kubernetes versions 1.32 through 1.36. Supported releases receive critical-issue patches and technical assistance from the community; development builds have no support.