180-java-observability-logging

# Java Logging Best Practices Implement effective Java logging following standardized frameworks, meaningful log levels, core practices (parameterized logging, exception handling, no sensitive data), flexible configuration, security-conscious logging, monitoring and alerting, and comprehensive logging validation through testing. **What is covered in this Skill?** - Standardized framework selection: SLF4J facade with Logback or Log4j2 - Meaningful and consistent log levels: ERROR, WARN, INFO, DEBUG, TRACE - Core practices: parameterized logging, proper exception handling, avoiding sensitive data - Configuration: environment-specific (logback.xml, log4j2.xml), output formats, log rotation - Security: mask sensitive data, control log access, secure transmission, GDPR/HIPAA compliance - Log monitoring and alerting: centralized aggregation (ELK, Splunk, Loki), automated alerts - Logging validation through testing: assert log messages, verify formats, test levels, measure performance impact **Scope:** The reference is organized by examples (good/bad code patterns) for each core area. Apply recommendations based on applicable examples. ## Constraints Before applying any logging recommendations, ensure the project compiles. Compilation failure is a blocking condition. After applying improvements, run full verification. - **MANDATORY**: Run `./mvnw compile` or `mvn compile` before applying any change - **SAFETY**: If compilation fails, stop immediately — do not proceed until resolved - **VERIFY**: Run `./mvnw clean verify` or `mvn clean verify` after applying improvements - **BEFORE APPLYING**: Read the reference for detailed good/bad examples, constraints, and safeguards for each logging pattern ## When to use this skill - Review Java code for logging and observability - Apply best practices for logging and observability in Java code ## Reference For detailed guidance, examples, and constraints, see [references/180-java-observability-logging.md](references/180-java-observability-logging.md).