eBPF Observability

eBPF (extended Berkeley Packet Filter) allows you to run sandboxed programs in the Linux kernel without modifying kernel source code or loading kernel modules. This skill covers using eBPF for deep observability, network monitoring, and security enforcement across cloud-native infrastructure.

1. When to Use

Use eBPF-based observability when you need:

• Deep performance debugging -- trace kernel-level latency, syscall overhead, and scheduling delays that application-level metrics cannot reveal.
• Network observability without sidecars -- capture L3/L4/L7 flows, DNS queries, and TCP state transitions directly from the kernel, eliminating the CPU and memory overhead of sidecar proxies.
• Security monitoring at the kernel boundary -- detect container escapes, unexpected process execution, sensitive file access, and anomalous syscall patterns in real time.
• Continuous profiling in production -- generate CPU flame graphs and memory allocation profiles with negligible overhead (typically under 1% CPU).
• Service mesh replacement or augmentation -- Cilium can replace kube-proxy and provide identity-aware network policies enforced at the kernel level.

Avoid eBPF when your kernel version is below 4.19, when you are running on managed platforms that restrict BPF capabilities, or when your debugging needs are fully met by application-level tracing.