Structured Logging in Spring Boot 4: JSON Logs Your ELK Stack Will Actually Parse
It’s 3 AM. A payment flow is failing for one customer out of thousands, and you’re grepping 40,000 lines of timestamp-soup for a single orderId — a value buried inside a formatted message, different on every line because someone wrote "order " + id + " failed" in one place and "failed order=" + id in another. This post kills that workflow. Structured logging turns every log line into a JSON document with named, typed fields your ELK stack can filter, aggregate, and alert on. Spring Boot has supported it natively since 3.4, and on Boot 4 it’s a one-property switch — no logstash-logback-encoder, no XML wrestling, no code changes. ...