Master eBPF for cloud-native observability with this essential probe cheat sheet. Covers kprobes, uprobes, and tracepoints for 2026 systems. Read now.
What eBPF Probes Actually Give You
eBPF lets you attach small, verified programs to points in the kernel and in user processes so you can observe behavior without rebuilding images or restarting workloads. In cloud-native systems—containers, short-lived pods, service meshes—that matters because traditional debug loops (log more, redeploy, hope the issue reproduces) are slow and often change the path you are trying to understand. Probes are the attachment points. Choose the wrong class and you either miss the event, attach to the wrong binary, or pay more overhead than the insight is worth.
Think of probes as three complementary surfaces: kernel dynamic entry points (kprobes), user-space dynamic entry points (uprobes), and stable kernel event contracts (tracepoints). A useful cheat sheet is less about memorizing every helper and more about knowing which surface answers which question under load.
Kprobes: Kernel Paths You Did Not Instrument Ahead of Time
Kprobes attach to almost any kernel function. They are the default when the failure lives below your application—syscalls, networking, scheduling, filesystem paths, or driver-adjacent code. Attach at function entry to see arguments and call frequency; use return probes when you care about return codes, latency, or how much work completed. Because the attach point is a function name (and offset in advanced cases), the same mental model works across hosts as long as the kernel symbols you target still exist.
Tradeoffs are real. Kernel functions are not a public API: renames, inlining, and config differences can break attachments. Always pair kprobe work with a clear exit plan—detach when done, keep programs small, and prefer read-only observation unless you fully understand the write path. For production cloud nodes, start with high-signal functions (syscall boundaries, socket send/receive, page fault related paths) rather than scattering probes across the entire call graph.
Uprobes: Debugging Inside Containers and Language Runtimes
Uprobes attach to symbols or offsets in a user binary or shared library. That is how you follow a request through a service binary, a TLS library, or a runtime without shipping a debug build. In Kubernetes-style environments, resolve the binary path carefully: the file you see from the host is not always the inode the container process is executing. Attach to the process’s actual mapped object, not a copy of the same path on the host rootfs.
Uprobes shine when the bug is application-level—handler latency, unexpected error returns, lock contention inside a library—while the kernel looks healthy. They cost more when the hot path is extremely tight, so prefer them on rare or medium-frequency events first. Combine with kprobes when you need both sides of a boundary: user code calling into a syscall, then the kernel path that actually fails.
Tracepoints First, Then Dynamic Probes
Tracepoints are predefined, stable event sites maintained with the kernel. When a tracepoint covers your question—block I/O, scheduler switches, network receive, syscall enter/exit—prefer it over a kprobe on the same path. You get a clearer event contract, better long-term portability across kernel builds, and usually less fragility when functions are inlined or renamed.
- Start with a question — latency, drops, errors, or unexpected control flow—not with a probe type.
- Prefer tracepoints when a stable event exists for that subsystem.
- Use kprobes when you need a kernel function the stable events do not expose.
- Use uprobes when the signal lives in a user binary or library inside the workload.
- Filter early — by cgroup, PID, mount namespace, or connection tuple so multi-tenant noise does not drown the signal.
For cloud-native debugging in practice: map the symptom to a layer (app, runtime, syscall, network, storage), pick the probe class for that layer, attach with tight filters, record only the fields you will act on, then remove the attachment. That sequence—more than any single helper name—is the probe cheat sheet that stays useful across 2026-era systems.