Monitoring and Observability

Monitoring is watching known measurements of a system, such as CPU use, error rate and response time, and alerting when they cross a threshold. Observability is the wider ability to understand why a system is behaving as it is from the data it produces, including problems nobody predicted.

It is built on three kinds of telemetry: metrics (numbers over time), logs (records of events) and traces (the path of one request through many services). Common tools are Prometheus and Grafana for metrics and dashboards, the ELK stack or Loki for logs, Jaeger for tracing, OpenTelemetry for collecting data, and hosted services such as Datadog and New Relic.