@bklarjs/logger 📝

Enterprise-grade structured logging system for bklar.

Unlike simple console loggers, this package provides a complete observability suite compatible with production standards (Datadog, CloudWatch, ELK), offering deep context injection, redaction, and log levels.

✨ Features

• 🏗️ Structured JSON: Standard output format for production ingestion.
• 🎨 Pretty Print: Beautiful, colorful output for local development.
• 🆔 Context Awareness: Automatically injects ctx.logger into every request, pre-bound with the requestId.
• 🕵️ Smart Redaction: Recursively sanitizes sensitive fields (passwords, tokens, secrets) before logging.
• 📊 Log Levels: Supports debug, info, warn, error, fatal.
• 🔗 Request Correlation: Generates or propagates X-Request-Id headers.

📦 Installation

This package is designed to work with bklar.

bun add bklar @bklarjs/logger

🚀 Usage

1. Setup Global Middleware

It is recommended to disable the default Bklar logger and use this middleware instead.

import { Bklar } from "bklar";
import { logger } from "@bklarjs/logger";

const app = Bklar({ logger: false }); // Disable default logger

// Apply middleware globally
app.use(logger());

app.get("/", (ctx) => {
  // Use the context logger!
  // It automatically includes the Request ID.
  ctx.logger.info("Handling root request");

  return ctx.json({ hello: "world" });
});

app.listen(3000);

2. Standalone Usage

You can use the logger class anywhere in your application (e.g., services, db connectors).

import { Logger } from "@bklarjs/logger";

const log = new Logger({ base: { service: "payment-service" } });

log.info("Service started");
log.error({ err: new Error("DB fail") }, "Connection failed");

🛡️ Automatic Redaction

The logger automatically removes sensitive keys from objects to prevent leaking secrets into logs.

Default keys redacted: password, token, secret, authorization, cookie, key.

ctx.logger.info(
  {
    user: "admin",
    password: "supersecretpassword", // Will become "[REDACTED]"
    metadata: { apiToken: "abc-123" }, // Will become "[REDACTED]"
  },
  "User login"
);

⚙️ Configuration

import { logger } from "@bklarjs/logger";

app.use(
  logger({
    // 'json' or 'pretty'. Defaults to 'pretty' in dev, 'json' in prod.
    format: "json",

    // Add more keys to redact
    redact: ["ssn", "credit_card"],

    // Minimum log level
    level: "debug",

    // Disable automatic request completion logging
    logRequests: true,
  })
);

🤝 Contributing

Contributions are welcome! Please open an issue or submit a Pull Request to the main bklar repository.

📄 License

This project is licensed under the MIT License.