Cilium vs linkerd: What are the differences?

Introduction

Cilium and linkerd are both popular service mesh technologies that enable advanced networking and security capabilities for containerized applications running in Kubernetes. While they have some similarities, they also have key differences that set them apart from each other. In this Markdown code, we will highlight the major differences between Cilium and linkerd.

1. Integration with Linux Networking Stack: Cilium operates at the Linux kernel level, leveraging eBPF (extended Berkeley Packet Filter) to provide low-level network visibility, load balancing, and security enforcement. On the other hand, linkerd is a layer 7 service mesh that integrates with Kubernetes service discovery and leverages proxying techniques to provide observability, reliability, and load balancing. This difference in integration allows Cilium to provide fine-grained network security policies and enforcement, while linkerd focuses more on higher-level service mesh functionality.

2. Service Discovery and Load Balancing: Cilium uses Envoy as its underlying proxy to provide service discovery and load balancing capabilities. It integrates with Kubernetes services and endpoints to dynamically manage traffic routing and load balancing. In contrast, linkerd has its own proxy implementation called linkerd-proxy that handles service discovery and load balancing. While both approaches are effective, this difference in proxy implementation may lead to variations in performance and behavior based on specific use cases and requirements.

3. Security Features: Cilium emphasizes strong network security by leveraging eBPF to enforce fine-grained network policies at the kernel level. It provides features such as identity-based access controls and application layer encryption. On the other hand, while linkerd also supports mutual TLS and encryption, it does not provide the same level of kernel-level security enforcement as Cilium. Linkerd focuses more on observability and reliability aspects of service mesh functionality.

4. Observability and Telemetry: Linkerd has a strong focus on providing powerful observability features for monitoring and debugging microservices. It offers detailed metrics, distributed tracing, and request-level telemetry. Cilium, on the other hand, provides visibility into network-level activity and performance metrics through eBPF-powered monitoring capabilities. The difference lies in the level of observability and telemetry provided, with linkerd focusing more on application-level information and Cilium providing deeper network-level insights.

5. Performance and Scalability: Cilium's integration with the Linux kernel and eBPF technology allows it to achieve high-performance networking and security operations. It can scale to handle large-scale deployments with thousands of microservices. Linkerd, while also performant, may have different performance characteristics depending on the workload and specific proxy implementation. The choice between Cilium and linkerd may depend on the performance and scalability requirements of the application.

6. Community and Ecosystem: Both Cilium and linkerd have active developer communities and ecosystems supporting them. However, they have different origins and focuses. Cilium has strong ties to the eBPF community and is backed by companies such as Isovalent and Red Hat. Linkerd, on the other hand, is a Cloud Native Computing Foundation (CNCF) project with strong ties to the Kubernetes community. The choice may depend on the existing ecosystem and community involvement that aligns with the organization's goals and preferences.

In Summary, Cilium differentiates itself from linkerd through its integration with the Linux networking stack, fine-grained network security enforcement at the kernel level, and deep network-level observability. Conversely, linkerd focuses more on layer 7 service mesh functionality, including service discovery, load balancing, application-level observability, and ease of use within the Kubernetes ecosystem. The choice between Cilium and linkerd depends on specific requirements, such as the need for network security, performance, ecosystem alignment, and level of observability needed.