DevOps Deep Dive

Monitoring & Alerting — Visibility into Production

You can't manage what you can't measure. Monitoring is the practice of collecting data about your systems: how fast are requests? How much disk space is left? Are users getting errors? Alerting wakes someone up when things go wrong. Together, they give you the visibility to operate systems confidently.

MetricsLoggingDistributed TracingAlertingDashboards
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Three Pillars

Observability Fundamentals

Metrics

Numeric measurements over time: request latency, error rate, queue depth, CPU usage, disk usage. Aggregated (p50, p95, p99) or individual data points.

  • System metrics: CPU, memory, disk, network.
  • Application metrics: requests/sec, error rate, latency.
  • Business metrics: transactions completed, revenue, user signups.
Logs

Detailed, unstructured (or structured) text output from services. What happened and when. Essential for debugging specific incidents.

  • Application logs: what your code is doing.
  • System logs: OS-level events (kernel panics, package updates).
  • Access logs: HTTP requests (who, when, what, response code).
Traces

Follow a single request through the entire system. Which services did it touch? How long in each? Where did it slow down?

  • Use case: debugging latency issues, understanding critical paths, visualizing service dependencies.
  • Tools: Jaeger, Zipkin, Datadog APM.