logback-config-rfc-27_skill

Overview

This skill provides an RFC-27 compliant static Logback configuration for Java services, focused on clear structure, environment-specific profiles, and production-friendly output. It explains where to place logback-spring.xml, which appenders and encoders to use, and deployment practices like not committing logback.xml to version control. Use it to set up or review consistent logging across services.

How this skill works

The configuration uses a root <configuration> element with springProfile blocks to apply different appenders and log levels per environment. It includes Console and RollingFile appenders, JSON encoding for production via LogstashEncoder, and encoder patterns for development. Logger overrides and async appenders are used to control noise and minimize runtime impact.

When to use it

• Setting up logging for a new Java service using Spring Boot
• Reviewing or auditing existing logback.xml/logback-spring.xml files
• Configuring environment-specific logging (local, dev, staging, production)
• Setting up log rotation, retention, and non-blocking appenders
• Preparing logs for structured downstream processing (JSON/Logstash)

Best practices

• Place logback-spring.xml in src/main/resources and avoid committing environment-specific logback.xml files
• Use <springProfile> to separate local (human-friendly) and production (JSON) formats
• Prefer ConsoleAppender for containers and RollingFileAppender for node-level persistence
• Use LogstashEncoder for structured JSON with MDC keys (traceId, spanId) in production
• Wrap appenders with AsyncAppender for high-throughput services to avoid blocking I/O

Example use cases

• Local development: ConsoleAppender with human-readable pattern and DEBUG root level
• Production: ConsoleAppender emitting JSON via LogstashEncoder and INFO root level
• Staging: Match production logging format but allow temporary increased verbosity for troubleshooting
• Microservice with heavy library noise: Add specific logger overrides (e.g., org.apache.kafka -> WARN)
• Services requiring traceability: include MDC keys like traceId and spanId in JSON encoder