using-logging

Working with Logging

Use structured logging with Pino throughout your application. Covers log levels, context, and workflow-safe logging patterns.

Implement Working with Logging

Use structured logging with Pino throughout your application. Covers log levels, context, and workflow-safe logging patterns.

See:

• Resource: using-logging in Fullstack Recipes
• URL: https://fullstackrecipes.com/recipes/using-logging

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Basic Logging

Import the logger and use it throughout your application:

import { logger } from "@/lib/logging/logger";

// Info level for normal operations
logger.info("Server started", { port: 3000 });

// Warn level for recoverable issues
logger.warn("Rate limit reached", { endpoint: "/api/chat" });

// Error level with Error objects
logger.error(err, "Failed to process request");

// Debug level for development troubleshooting
logger.debug("Cache miss", { key: "user:123" });

Structured Logging

Always include context as the first argument for structured logs:

// Context object first, message second
logger.info({ userId: "123", action: "login" }, "User logged in");

// For errors, pass the error first
logger.error({ err, userId: "123", endpoint: "/api/chat" }, "Request failed");

Log Levels

Use appropriate levels for different scenarios:

| Level | When to Use | | trace | Detailed debugging (rarely used) | | debug | Development troubleshooting | | info | Normal operations, business events | | warn | Recoverable issues, deprecation warnings | | error | Failures that need attention | | fatal | Critical failures, app cannot continue |

Configuring Log Level

Set the LOG_LEVEL environment variable:

# Show all logs including debug
LOG_LEVEL="debug"

# Production: only warnings and errors
LOG_LEVEL="warn"

Default is info if not set. Valid values: trace, debug, info, warn, error, fatal.

Logging in API Routes

import { logger } from "@/lib/logging/logger";

export async function POST(request: Request) {
  const start = Date.now();

  try {
    const result = await processRequest(request);

    logger.info(
      { duration: Date.now() - start, status: 200 },
      "Request completed",
    );

    return Response.json(result);
  } catch (err) {
    logger.error({ err, duration: Date.now() - start }, "Request failed");

    return Response.json({ error: "Internal error" }, { status: 500 });
  }
}

Logging in Workflows

Workflow functions run in a restricted environment. Use the logger step wrapper:

// src/workflows/chat/steps/logger.ts
import { logger } from "@/lib/logging/logger";

export async function log(
  level: "info" | "warn" | "error" | "debug",
  message: string,
  data?: Record<string, unknown>,
): Promise<void> {
  "use step";

  if (data) {
    logger[level](data, message);
  } else {
    logger[level](message);
  }
}

Then use it in workflows:

import { log } from "./steps/logger";

export async function chatWorkflow({ chatId }) {
  "use workflow";

  await log("info", "Workflow started", { chatId });
}

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References

• Pino Documentation
• Pino Log Levels