Prometheus Labels Are Part of the API
Label names and cardinality are query contracts for dashboards, recording rules and alerts.
labels
Do Not Turn Source IP into a High-Cardinality Metric Label
Security logs contain useful source addresses, but promoting every IP to a Prometheus or Loki index label would create unbounded cardinality on an Internet-facing service.
Labels and Selectors: The Tiny Contract That Can Break an Entire Service
Why the app label shared by a Deployment and Service matters more than it looks.