Logging Best Practices Skill

Logging Best Practices

Emit structured logs with Pino throughout the app.

Prerequisites

Complete these setup recipes first:

Pino Logging Setup

Logging

Import logger from @/lib/logging/logger. Pass a context object first, message second. For errors, put err in the context object.

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

logger.info({ port: 3000 }, "Server started");
logger.warn({ endpoint: "/api/chat" }, "Rate limit reached");
logger.debug({ key: "user:123" }, "Cache miss");
logger.error({ err, userId: "123", endpoint: "/api/chat" }, "Request failed");

Levels

| 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 |

Set the active threshold via LOG_LEVEL (defaults to info). Use warn in production.

LOG_LEVEL="debug"

In API Routes

Log on the way out with timing context.

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 });
  }
}

In Workflows

The workflow runtime can't import Node modules, so the logger can't be called directly. Wrap it in a "use step" function.

// 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);
  }
}

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

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

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

Agent Skills: Logging Best Practices

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