---

name: structured-logging-standardizer description: Enforces consistent structured logging with request correlation IDs, standardized log schema, middleware integration, and best practices. Use for "structured logging", "log standardization", "request tracing", or "log correlation".

Structured Logging Standardizer

Implement consistent, queryable, correlated logs.

Log Schema

Copyinterface LogEntry {
  timestamp: string; // ISO 8601
  level: "debug" | "info" | "warn" | "error" | "fatal";
  message: string;
  service: string;
  environment: string;

  // Request context
  requestId?: string;
  traceId?: string;
  userId?: string;

  // Additional context
  [key: string]: any;
}

Request ID Middleware

Copyimport { v4 as uuidv4 } from "uuid";

app.use((req, res, next) => {
  // Generate or use existing request ID
  req.id = req.headers["x-request-id"] || uuidv4();

  // Add to response headers
  res.setHeader("x-request-id", req.id);

  // Store in async local storage
  asyncLocalStorage.run(new Map(), () => {
    asyncLocalStorage.getStore()?.set("requestId", req.id);
    next();
  });
});

// Logger with request context
const logger = pino({
  mixin() {
    return {
      requestId: asyncLocalStorage.getStore()?.get("requestId"),
    };
  },
});

Standardized Logger

Copyclass StandardLogger {
  private logger = pino();

  info(message: string, context?: Record<string, any>) {
    this.logger.info(
      {
        ...this.getContext(),
        ...context,
      },
      message
    );
  }

  error(message: string, error?: Error, context?: Record<string, any>) {
    this.logger.error(
      {
        ...this.getContext(),
        ...context,
        error: {
          message: error?.message,
          stack: error?.stack,
          name: error?.name,
        },
      },
      message
    );
  }

  private getContext() {
    return {
      requestId: asyncLocalStorage.getStore()?.get("requestId"),
      userId: asyncLocalStorage.getStore()?.get("userId"),
    };
  }
}

Best Practices

Copy// ✅ DO: Structured fields
logger.info({ userId: '123', action: 'purchase', amount: 99.99 }, 'Purchase completed');

// ❌ DON'T: String interpolation
logger.info(\`User 123 purchased for $99.99\`);

// ✅ DO: Consistent field names
logger.info({ duration_ms: 150 }, 'Request completed');

// ❌ DON'T: Inconsistent naming
logger.info({ durationMs: 150 }, 'Request done');

Output Checklist

• Request ID middleware
• Structured log schema
• Correlation IDs
• Standardized logger
• Best practices documented ENDFILE