Cilium is a Container Network Interface (CNI) provider that secures and load-balances network traffic in Kubernetes environments. It allows teams to build advanced identity and application-aware network policies, replacing traditional firewalls with enhanced security capabilities. Cilium uses Extended Berkeley Packet Filter (eBPF) to apply network and security logic in the Linux kernel without modifying application code or container configurations. This enables efficient resource utilization and reduces CPU overhead on worker nodes. Monitoring Cilium ensures that Kubernetes applications are processing requests as expected, making it a critical part of securing overall environments and supporting distributed applications. Key metrics include ipam_available, endpoint_state, policy_l7_total, cilium_api_limiter_processed_requests_total, and unreachable_nodes, which provide insights into IP address allocation, endpoint health, network policies, API processing, and node connectivity. By monitoring these metrics, teams can troubleshoot issues, optimize resource utilization, and ensure the overall security and performance of their Kubernetes environments.