Generic Winston Logger Service

Create a robust, scalable Winston logger service for Node.js projects with daily log rotation, environment-aware formatting, and proper object serialization to prevent [object Object] errors.

Prompt

Role & Objective

Create a generic, robust, and scalable Winston logger service for Node.js applications. The logger must be reusable across projects and handle common logging issues like object serialization.

Operational Rules & Constraints

1. Dependencies: Use

   winston

   and

   winston-daily-rotate-file

   .
2. Transports: Configure both Console and DailyRotateFile transports.
3. Log Format:
   • Use

     winston.format.metadata()

     to capture metadata.
   • Use ISO 8601 timestamps:

     YYYY-MM-DDTHH:mm:ssZ

     .
   • Implement a custom

     printf

     function that formats the log string.
4. Object Serialization: Ensure that metadata objects and arrays are serialized using

   JSON.stringify(metadata, null, 2)

   to prevent

   [object Object]

   output.
5. Environment Awareness:
   • Check

     process.env.NODE_ENV === 'development'

     .
   • Apply

     winston.format.colorize()

     to the console transport only in development.
6. Log Rotation:
   • Rotate logs daily (

     datePattern: "YYYY-MM-DD"

     ).
   • Enable

     zippedArchive: true

     .
   • Set

     maxSize: "20m"

     and

     maxFiles: "14d"

     .
7. Exception Handling:
   • Enable

     handleExceptions: true

     and

     exitOnError: false

     on transports.
   • Listen for

     unhandledRejection

     events and log them using the logger.
8. Parameters: The function should accept

   appName

   ,

   logPath

   (defaulting to current working directory), and

   logLevel

   (defaulting to "info").

Anti-Patterns

• Do not use deprecated timestamp formats.
• Do not allow

  [object Object]

  in log output.
• Do not colorize logs in production environments.

Triggers

• create a generic logger
• winston logger service
• robust logging setup
• fix [object Object] in logs
• scalable logger configuration