The CNI debate is over; the hard work of migration, observability integration, and eBPF skill-building has just begun.
Cilium has emerged as the dominant Kubernetes CNI, graduating from CNCF in 2023 and becoming the default networking layer for GKE, EKS, and AKS, with adoption exceeding 40% in production environments according to the CNCF 2023 Annual Survey. Platform teams that have been watching the CNI landscape consolidate now face a different and more demanding set of decisions: how to migrate without downtime, how to integrate Hubble into existing observability stacks, and how to close the eBPF knowledge gap before it becomes an operational liability.
The CNI Consolidation Is Real and Cloud Providers Are Driving It
The shift to Cilium is no longer driven by community enthusiasm alone; it is being mandated by infrastructure defaults at the hyperscaler level. GKE Autopilot defaulted to Cilium in 2022, Azure CNI Powered by Cilium reached general availability in 2023, and AWS introduced eBPF-based dataplane support for EKS the same year. This convergence means that platform teams inheriting cloud-managed clusters may already be running Cilium without having made an explicit architectural decision to do so. For teams still operating self-managed clusters with Flannel, Calico, or Weave, the pressure to migrate is intensifying as those projects receive diminishing investment relative to Cilium's rate of development. The practical implication is straightforward: Cilium is now the safe, well-supported default, and continuing to operate legacy CNIs carries increasing risk in terms of both feature gaps and long-term maintainability.
Migration Strategy, Kernel Dependencies, and the Observability Integration Path
Migrating an existing cluster's CNI in place remains one of the more operationally sensitive procedures in the Kubernetes lifecycle, and Cilium's feature set introduces real infrastructure prerequisites that teams must address before cutting over. Cilium requires a minimum Linux kernel version of 4.9.17, but teams need kernel 5.10 or later to unlock the full feature set, including WireGuard-based transparent encryption, the eBPF kube-proxy replacement, and Bandwidth Manager for egress rate limiting. This creates a meaningful dependency chain for teams running older RHEL 7 or Ubuntu 18.04 LTS nodes, where kernel upgrades may require full node replacement rather than in-place patching. Once the infrastructure baseline is confirmed, the observability integration work begins with Hubble, Cilium's built-in network visibility layer, which exposes per-flow telemetry, service dependency graphs, and Prometheus-compatible metrics via eBPF without requiring a sidecar. Connecting Hubble's metrics endpoint to an existing Grafana and Prometheus stack is well-documented but requires platform teams to make deliberate decisions about cardinality, retention, and how Hubble's Layer 4 and Layer 7 flow data complements or replaces existing network monitoring tooling.
Closing the eBPF Skill Gap and Rethinking the Networking Stack
The deeper operational challenge for platform teams is that Cilium's power comes from eBPF internals that most platform engineers have not needed to understand until now, and troubleshooting production incidents without that foundation leads to slower mean time to resolution and overreliance on vendor support. Engineers who previously diagnosed networking issues with iptables rules and tcpdump now need familiarity with tools like bpftool, cilium-dbg, and the Hubble CLI to trace flows, inspect BPF maps, and identify policy enforcement points in the kernel. Beyond individual troubleshooting skills, teams also need to develop internal conventions around CiliumNetworkPolicy CRDs, which extend standard Kubernetes NetworkPolicy with Layer 7 awareness and DNS-based egress controls, creating a dual-policy surface that can produce confusing behavior if managed inconsistently. The broader architectural shift is equally significant: Cilium's sidecar-free service mesh mode, which runs Envoy as a per-node proxy rather than injecting it into every pod, directly challenges Istio's deployment model and gives platform teams a credible path to mutual TLS, traffic management, and Layer 7 observability without the operational overhead of a traditional service mesh. Tetragon, the CNCF security observability project that integrates tightly with Cilium, extends this same eBPF-based control plane into runtime threat detection and enforcement, collapsing what was previously a three-layer stack of CNI, service mesh, and security tooling into a single coherent system.
Conclusion
The CNI war produced a clear winner, but the real work for platform teams starts after that verdict is accepted. Over the next 12 to 24 months, the teams that pull ahead will be those that treat the Cilium migration not as a networking swap but as a platform modernization event, using it as the forcing function to upgrade kernel baselines, consolidate observability tooling around Hubble and Tetragon, and build internal eBPF literacy through structured runbooks and incident postmortems. The convergence of networking, security, and observability into a single eBPF control plane is not a temporary trend; it reflects a durable shift in how Linux-based infrastructure exposes kernel primitives to higher-level orchestration systems. Platform teams that invest now in understanding those primitives will be far better positioned to take advantage of what comes next, including hardware offload via XDP, deeper integration with service mesh standards, and eBPF-based policies that span across clusters and clouds.
Technologies covered: Cilium, eBPF, Kubernetes CNI, Hubble, Network policies
Sources aggregated from: DevOps Weekly, GitHub Trending, Hacker News, InfoQ, The New Stack
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