Logging

When to Use

• Setting up structured logging in a new application or service
• Replacing console.log or print() with proper logging infrastructure
• Adding request tracing with correlation IDs across microservices
• Redacting sensitive data (passwords, tokens, PII) from log output
• Building observability pipelines with log aggregation (ELK, Datadog, CloudWatch)

When NOT to Use

• Static analysis or linting tasks that do not involve runtime output
• Pure computation functions where logging would add unnecessary noise
• Test assertions — use testing frameworks' built-in assertion messages, not log output

Core Patterns