Tracing

OpenTelemetry baggage is a context-associated collection of string key-value pairs. It lets information known near a request’s entry point travel to downstream operations: a deployment region or a rollout cohort, for example. Unlike a span attribute, baggage is intended for propagation. Unlike trace context, it describes application-selected information rather than the identifiers and flags connecting spans. These mechanisms can travel together without being the same data structure. ...

BPF and kernel tracepoints let you observe behavior at the source with a tiny footprint: no agent, no restart, no stopping the workload. Traditional profiling means installing something, restarting with flags, or pausing the process — each of which perturbs the system under study or is forbidden in production. A BPF probe attaches to an already-running kernel, collects its answer, and detaches, leaving the workload exactly as it found it. ...

Trace sampling selects which recorded work reaches the tracing pipeline. It can reduce export traffic and storage, but a configured percentage is not a strict ceiling on bytes, processor time, or money. Requests produce different numbers of spans, attributes vary in size, and traffic itself changes. A one-percent policy applied to a sudden tenfold traffic increase can still produce roughly ten times as much sampled data. ...

A distributed trace connects recorded operations through a shared trace identifier and explicit relationships. A span represents one operation, with start and end timestamps, attributes, events, and status. This makes a trace useful when a checkout request crosses an application, an inventory service, and a payment service. The resulting picture depends on which operations were instrumented, retained, and exported; it is not an automatic inventory of every action the request performed. ...