How to customize the log format of Debian Node.js

This article will guide you on how to customize the log format of your Node.js application on your Debian system, taking the Winston log library as an example.

Step 1: Install Winston

First, make sure Winston is installed. If not installed, please execute the following command in the project root directory:

 npm install winston

Step 2: Create a custom log format

Create a file named logger.js and write the following code to define a custom log format:

 const { createLogger, format, transports } = require('winston');

const customFormat = format.combine(
  format.timestamp({ format: 'YYYY-MM-DD HH:mm:ss' }),
  format.printf(({ timestamp, level, message }) => {
    return `[${timestamp}] ${level.toUpperCase()}: ${message}`;
  })
);

const logger = createLogger({
  level: 'info',
  format: customFormat,
  transports: [
    new transports.Console(),
    new transports.File({ filename: 'logs/app.log' })
  ]
});

module.exports = logger;

This code snippet defines a custom log format that contains timestamps, log levels, and messages. The log output will be written to the console and a file named app.log at the same time (located in the logs directory, please make sure that the directory exists).

Step 3: Use a custom logger in your application

Import and use a custom logger in your main application file (such as app.js ):

 const logger = require('./logger');

logger.info('Application started successfully');
logger.error('An error occurred!');

After running the application, the logs will be output to the console and logs/app.log files in the format you have defined.

Extensions and supplements

Winston offers a wealth of formatting options and customization features, so you can adjust log formats according to your needs. For more information, please refer to the official documentation: https://www.php.cn/link/6a710cdccdb02b3301d71d83ed3d15b3 For example, you can add additional context information to the log, or use different log levels for finer log management. Remember to create the logs directory, otherwise the file writing will fail.

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