mcpbeat

Logging Best Practices

secondsky/logging-best-practices

Structured logging with proper levels, context, PII handling, centralized aggregation. Use for application logging, log management integration, distributed tracing, or encountering log bloat, PII exposure, missing context errors.

2k tokens
context cost
the whole folder, loaded on every use
2
files
instructions only
0
copies elsewhere
how many repositories repackaged it
202
stars on the repo
on the repository, not the skill itself

Install

one command, takes just this skill from the repository 
npx skills add https://github.com/secondsky/claude-skills --skill logging-best-practices

The instruction itself

8 sections, as written by the author

Logging Best Practices

Implement secure, structured logging with proper levels and context.

Log Levels

| Level | Use For | Production |

|-------|---------|------------|

| DEBUG | Detailed debugging | Off |

| INFO | Normal operations | On |

| WARN | Potential issues | On |

| ERROR | Errors with recovery | On |

| FATAL | Critical failures | On |

Structured Logging (Winston)

const winston = require('winston');

const logger = winston.createLogger({
  level: process.env.LOG_LEVEL || 'info',
  format: winston.format.combine(
    winston.format.timestamp(),
    winston.format.json()
  ),
  defaultMeta: { service: 'api-service' },
  transports: [
    new winston.transports.Console(),
    new winston.transports.File({ filename: 'error.log', level: 'error' })
  ]
});

// Usage
logger.info('User logged in', { userId: '123', ip: '192.168.1.1' });
logger.error('Payment failed', { error: err.message, orderId: '456' });

Request Context

const { AsyncLocalStorage } = require('async_hooks');
const storage = new AsyncLocalStorage();

app.use((req, res, next) => {
  const context = {
    requestId: req.headers['x-request-id'] || uuid(),
    userId: req.user?.id
  };
  storage.run(context, next);
});

function log(level, message, meta = {}) {
  const context = storage.getStore() || {};
  logger.log(level, message, { ...context, ...meta });
}

PII Sanitization

const sensitiveFields = ['password', 'ssn', 'creditCard', 'token'];

function sanitize(obj) {
  const sanitized = { ...obj };
  for (const field of sensitiveFields) {
    if (sanitized[field]) sanitized[field] = '[REDACTED]';
  }
  if (sanitized.email) {
    sanitized.email = sanitized.email.replace(/(.{2}).*@/, '$1***@');
  }
  return sanitized;
}

Best Practices

  • Use structured JSON format
  • Include correlation IDs across services
  • Sanitize all PII before logging
  • Use async logging for performance
  • Implement log rotation
  • Never log at DEBUG in production

Additional Implementations

See references/advanced-logging.md for:

  • Python structlog setup
  • Go zap high-performance logging
  • ELK Stack integration
  • AWS CloudWatch configuration
  • OpenTelemetry tracing

Never Do

  • Log passwords or tokens
  • Use console.log in production
  • Log inside tight loops
  • Include stack traces for client errors

How to use it

Copy the folder

Take secondsky/logging-best-practices from the repository into ~/.claude/skills for personal use, or into .claude/skills inside a project.

Check the name does not clash

The agent identifies a skill by the name field in its header. Two skills with the same name cannot sit side by side — one of them will be ignored.