什么叫可观测性

今天看OTel时，学到的比较标准的定义，作一个记录。

https://opentelemetry.io/docs/concepts/observability-primer/#what-is-observability

Observability lets us understand a system from the outside, by letting us ask questions about that system without knowing its inner workings. Furthermore, it allows us to easily troubleshoot and handle novel problems (i.e. “unknown unknowns”), and helps us answer the question, “Why is this happening?”

In order to be able to ask those questions of a system, the application must be properly instrumented. That is, the application code must emit signals such as traces, metrics, and logs. An application is properly instrumented when developers don’t need to add more instrumentation to troubleshoot an issue, because they have all of the information they need.

OpenTelemetry is the mechanism by which application code is instrumented, to help make a system observable.