Logging is an essential part of any application, providing developers with valuable information about its behavior and helping to diagnose issues. Real-time logging takes this a step further by allowing developers to monitor log messages as they are generated, providing instant feedback and insights into the application’s runtime behavior.

In this blog post, we will explore how to implement real-time logging in a Node.js application using Pino, a fast and lightweight logger for Node.js. We will cover the following topics:

1. Installing Pino
2. Setting up real-time logging with Pino
3. Customizing log messages
4. Filtering log messages

Let’s get started!

Installing Pino

To install Pino in your Node.js project, run the following command:

npm install pino

Setting up real-time logging with Pino

Pino provides a flexible and easy-to-use API for logging. To start using Pino, require it in your Node.js application:

const pino = require('pino');

Next, create a logger instance:

const logger = pino();

This creates a default logger that logs messages to the console. You can now use the logger to start logging messages:

logger.info('Hello, world!');
logger.error('Something went wrong');

By default, each log message is formatted with a timestamp, log level, and the log message itself.

Customizing log messages

Pino allows you to customize log messages by providing additional metadata. For example, you can add a unique request ID to each log message to trace its origin:

const logger = pino({
  mixin() {
    return { requestId: generateRequestId() };
  }
});

With the above configuration, each log message will include a requestId field.

Filtering log messages

Pino also provides a powerful filtering mechanism that allows you to control which log messages are outputted. You can filter log messages based on their log level, define custom rules, or even sample log messages to reduce the volume of logs.

To filter log messages based on their log level, set the level option when creating the logger:

const logger = pino({
  level: 'info'
});

With the above configuration, only log messages with a info level or higher will be outputted.

Conclusion

In this blog post, we learned how to implement real-time logging in a Node.js application using the Pino logger. We covered the installation process, setting up the logger, customizing log messages, and filtering log messages.

Pino’s straightforward API and rich feature set make it a great choice for logging in Node.js applications. Its speed and low overhead make it suitable for high-performance scenarios as well.

#nodejs #logging