What is instrumentation? and how does it work in Jaegar ?

Instrumentation is the process of generating telemetry data(logs, metrics, and traces) from your application code. It is essentially writing code that enables your application code to emit telemetry data, which can be used later to investigate issues.

Most distributed tracing tools offer clients libraries, agents, and SDKs to instrument application code. Jaeger's client libraries for instrumentation are based on OpenTracing APIs.

OpenTracing was an open-source project aimed at providing vendor-neutral APIs and instrumentation for distributed tracing. It later got merged into OpenTelemetry. Jaeger has official client libraries in the following languages:

Go

Java

Node.js

Python

C++

C#

When a service is instrumented, it generates spans for incoming transactions and attaches trace context to outgoing transactions.