Structured Logging in Go with slog for Observability and Alerting

Logs are a debugging interface you can still use when the system is on fire. The problem is that plain text logs age poorly: as soon as you need filtering, aggregation, and alerting, you start parsing sentences. Structured logging is the antidote. It turns every log line into a small event with stable fields, so tools can search and aggregate reliably. For how logs connect to metrics, dashboards, and alerting in the wider stack, see the Observability: Monitoring, Metrics, Prometheus & Grafana Guide. What structured logging is and why it scales Structured logging is logging where a record is not just a string, but a message plus typed key value attributes. The idea is boring in the best way: once logs are machine-readable, an incident stops being a grep contest. A quick comparison: Plain text (human-first, tool-hostile) failed to charge card user=42 amount=19.99 ms=842 err=timeout Structured (tool-first, still readable) {"msg":"failed to charge card","user_id":42,"amount":19.99,"dur