as-app/src/lib/logger

Centralized Logging System

A flexible, scope-based logging system for React Native applications that provides consistent log formatting and environment-based filtering.

Features

• Scope-based logging for better organization and filtering
• Environment-based configuration
• Consistent log formatting with timestamps
• Development vs Production configurations
• Multiple log levels (debug, info, warn, error)
• Easy integration with existing codebase

Installation

The logger is already integrated into the project. No additional installation steps required.

Usage

Basic Usage

import { createLogger } from "~/lib/logger";

// Create a logger with scopes
const logger = createLogger({
  component: "MyComponent",
  feature: "authentication",
});

// Use different log levels
logger.debug("Debug message", { additionalData: "value" });
logger.info("Info message");
logger.warn("Warning message", { threshold: 100 });
logger.error("Error message", new Error("Something went wrong"));

Configuration

Configure the logging system through environment variables:

• APP_LOG_SCOPES: Comma-separated list of enabled scope names

  APP_LOG_SCOPES=api,auth,network
  

  If not set, all scopes are enabled

• APP_LOG_MIN_LEVEL: Minimum log level to display

  APP_LOG_MIN_LEVEL=warn  // Only show warn and error logs
  

  Defaults to:

  • Development: "debug"
  • Production: "info"

Log Levels

• debug: Detailed information for debugging
• info: General information about application operation
• warn: Warning messages for potentially problematic situations
• error: Error messages for serious problems

Output Format

[timestamp] [LEVEL] [scope1,scope2] message additional_data

Example:

[2025-02-17T10:39:35.123Z] [INFO] [api,network] Request completed { status: 200 }

Best Practices

1. Use Meaningful Scopes

   // Good
   const logger = createLogger({
     component: "UserProfile",
     feature: "authentication",
   });
   
   // Not as descriptive
   const logger = createLogger({
     scope: "general",
   });
   

2. Include Relevant Context

   // Good
   logger.error("Failed to fetch user data", {
     userId,
     error: error.message,
     statusCode: error.status,
   });
   
   // Missing important context
   logger.error("Failed to fetch user data");
   

3. Use Appropriate Log Levels

   • debug: Development/debugging information
   • info: Normal application flow
   • warn: Potential issues that don't block operation
   • error: Serious problems requiring attention

4. Group Related Logs

   // Group related operations under the same scopes
   const authLogger = createLogger({
     module: "auth",
     feature: "login",
   });
   
   authLogger.info("Login attempt", { username });
   authLogger.debug("Validating credentials");
   authLogger.info("Login successful");
   

Examples

See example.js for more usage examples.

Production Considerations

1. Use APP_LOG_SCOPES to filter logs in production:

   APP_LOG_SCOPES=api,auth  // Only show logs from api and auth scopes
   

2. Set appropriate minimum log level:

   APP_LOG_MIN_LEVEL=warn  // Only show warnings and errors
   

3. Consider log volume and performance:

   • Avoid excessive debug logs in production
   • Include only necessary context in log messages
   • Use appropriate log levels to manage output

Contributing

When adding new features or components:

1. Create a logger with descriptive scopes
2. Use consistent log levels
3. Include relevant context in log messages
4. Document any new logging patterns