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Introduction to Log-Express

Welcome to Log-Express, a powerful and customizable logging middleware designed for Express.js applications. Whether you're building a small project or a large-scale application, Log-Express provides an efficient and flexible solution for logging API requests.

Key Features​

  • Customizable Log Levels: Control the verbosity of your logs with log levels like trace, debug, info, warn, error, and fatal.
  • Console and File Logging: Log messages can be printed to the console, saved to log files, or both.
  • Daily Log Rotation: Optionally split log files by day for easier organization.
  • Intelligent Request Logging: Automatically log HTTP methods, URLs, status codes, response times, and client IPs.
  • Minimal Setup: Log-Express is easy to integrate with any Express.js application, requiring minimal configuration to get started.

Why Use Log-Express?​

Effective logging is crucial for monitoring and debugging Express applications, and Log-Express simplifies this process by offering:

  • Granular Control: Define what gets logged based on log levels and routes.
  • Multi-Destination Logging: Choose where to log—either to files, the console, or both.
  • Scalable for Projects: Suitable for both development and production environments.

Installation​

To install Log-Express, simply run:

npm install log-express

Usage Example​

Below is a simple example of how to integrate Log-Express into your Express application:

const express = require("express");
const logExpress = require("log-express");

const app = express();

// Middleware configuration
app.use(
  logExpress({
    logLevel: "info", // Set log level (default: 'info')
    consoleLog: true, // Enable console logging (default: true)
    saveLogs: true, // Enable file logging (default: false)
    logPerDay: true, // Split logs by day (default: false)
  })
);

// Dummy API endpoints

app.get("/", (req, res) => {
  res.send("Hello, world!");
});

app.get("/api/users", (req, res) => {
  res.send("Hello, users!");
});

app.listen(3000, () => {
  console.log("Server running on port 3000");
});

Configuration Options​

Log-Express provides several configuration options to tailor logging to your specific needs:

  • logLevel: Define the minimum log level (trace, debug, info, warn, error, fatal). Logs with a level below this threshold will be ignored.
    • Default: "info"
  • consoleLog: Enable or disable logging to the console.
    • Default: true
  • saveLogs: Enable saving logs to a file. Log files are stored in a logs directory at the project’s root.
    • Default: false
  • logPerDay: If enabled, logs will be split into daily files with filenames in the format system-YYYY-MM-DD.logs.
    • Default: false

Example Logs​

When using Log-Express, your logs will look like this:

2024-09-18 14:32:07 [INFO]: GET /api/users 200 23ms - 192.168.1.1
2024-09-18 14:33:10 [WARN]: GET /api/orders 404 15ms - 192.168.1.2
2024-09-18 14:34:02 [ERROR]: POST /api/auth 500 45ms - 192.168.1.3
2024-09-18 14:35:45 [INFO]: PUT /api/products/123 204 34ms - 192.168.1.4

Logging Levels​

Log-Express supports the following logging levels, which allow you to filter logs based on the severity of events:

  • trace: Detailed information useful for debugging.

  • debug: Debugging information.

  • info: Informational messages indicating normal operation

  • warn: Warnings that indicate potential issues but do not stop the execution of your application.

  • error: Errors that prevent part of your application from functioning correctly.

  • fatal: Critical issues that may cause the application to crash.

  • off: No logging will take place at this level.

Customization and Flexibility​

Log-Express provides the ability to customize the log format and logging behavior to fit your application's needs. You can easily configure it to log important request data such as:

  • HTTP Methods: GET, POST, PUT, DELETE, etc.
  • Response Status Codes: Success, client errors, server errors.
  • Response Time: Duration of the request, measured in milliseconds.
  • Client IP Address: The origin IP of the request.

These details make it easier to track how your API is being used and detect issues early on.

Best Practices​

  1. Log Levels in Production: In production environments, it's generally best to log at the info level or higher (e.g., warn, error) to reduce verbosity and focus on important events.
  2. Log Rotation: Enabling logPerDay ensures that your log files are manageable and easy to navigate. This is especially helpful for long-running applications.
  3. Monitoring Tools: Combine Log-Express with monitoring tools to gain deeper insights into your application’s performance and behavior.