logging

Logging Standards

Logger Usage

Use Logger Factory

Use @lib/logger-factory for auditLogger, systemLogger, or browserLogger instead of console.log.

Logger Types

auditLogger

• Usage: API routing ONLY
• Output: Writes to audit_log database table
• When: For tracking API requests and user actions

import { auditLogger } from '@/lib/logger-factory';

export const POST = async (request: NextRequest) => {
  auditLogger.info('API request received', { endpoint: '/api/users' });
  // Implementation
};

browserLogger

• Usage: Browser context ONLY
• Output: Writes to browser console
• When: For client-side debugging and development

import { browserLogger } from '@/lib/logger-factory';

browserLogger.info('Component mounted', { component: 'UserCard' });

systemLogger

• Usage: Everywhere else (server-side, background jobs, etc.)
• Output: Writes to log file
• When: For general application logging

import { systemLogger } from '@/lib/logger-factory';

systemLogger.error('Database connection failed', { error });

Logging Best Practices

Log Levels

• Use appropriate log levels (debug, info, warn, error)
• Log errors with context
• Log important business events
• Avoid logging sensitive data

Log Context

• Include relevant context in log messages
• Use structured logging when possible
• Include request IDs for tracing
• Log performance metrics when appropriate

Prohibited Patterns

❌ NEVER DO:

• Use console.log in production code
• Log sensitive data (passwords, tokens, PII)
• Log full request/response bodies
• Use console methods directly

✅ ALWAYS DO:

• Use appropriate logger from logger-factory
• Log only metadata and non-sensitive information
• Use structured logging with context
• Follow logging standards for each environment

References

• Security: See general/security.mdc
• Error Handling: See topics/quality/error-handling.mdc