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Service Logs Feature ​

A comprehensive logging solution for polyglot microservices that provides both CLI and web-based log viewing capabilities.

Features ​

📋 CLI Log Viewer ​

View logs directly from the command line with powerful filtering and export options:

bash
# View all service logs
create-polyglot logs

# View logs for a specific service
create-polyglot logs my-service

# Follow logs in real-time
create-polyglot logs --follow

# Show last 100 lines
create-polyglot logs --tail 100

# Filter by log level
create-polyglot logs --level error

# Show logs from the last hour
create-polyglot logs --since 1h

# Search logs with regex
create-polyglot logs --filter "database|connection"

# Export logs to JSON
create-polyglot logs --export json

# Clear all logs
create-polyglot logs --clear

🌐 Web Dashboard ​

Enhanced admin dashboard with integrated log viewer:

  • Real-time log streaming via WebSocket connection
  • Service filtering - view logs from specific services
  • Log level filtering - filter by error, warn, info, debug
  • Text search - search through log messages
  • Auto-refresh - automatically update logs every few seconds
  • Export functionality - download logs in various formats

Access the dashboard:

bash
create-polyglot admin

🗂️ File-based Storage ​

Logs are stored in each service directory under .logs/:

apps/
  my-service/
    .logs/
      2025-11-05.log    # Daily log files
      2025-11-04.log
      logger.js         # Helper utility for services

📊 Log Format ​

All logs use a consistent JSON format:

json
{
  "timestamp": "2025-11-05T14:30:00.000Z",
  "level": "info",
  "service": "my-service",
  "message": "GET /api/users",
  "data": {
    "method": "GET",
    "path": "/api/users",
    "ip": "127.0.0.1"
  }
}

🔄 Log Rotation ​

  • Files automatically rotate when they exceed 10MB
  • Keeps the last 10 log files per service
  • Old files are cleaned up automatically

Service Integration ​

Node.js Services ​

Services automatically include request logging and error handling:

javascript
import { Logger } from './.logs/logger.js';
const logger = new Logger('my-service');

logger.info('Server started', { port: 3001 });
logger.error('Database connection failed', { error: err.message });

Python Services (FastAPI) ​

Built-in logging with automatic request tracking:

python
file_logger.info("Processing request", {"user_id": 123})
file_logger.error("Validation failed", {"field": "email"})

Go Services ​

Structured logging with request middleware:

go
logger.Info("User authenticated", map[string]interface{}{
    "user_id": userID,
    "role": "admin",
})

Java Services (Spring Boot) ​

Integrated with SLF4J and automatic request logging:

java
logInfo("Processing payment", Map.of("amount", 100.50));
logError("Payment failed", Map.of("error", ex.getMessage()));

API Endpoints ​

Each service automatically exposes log endpoints:

bash
# Get recent logs for a service
GET http://localhost:3001/logs?tail=50&level=error

# Parameters:
# - tail: number of recent lines (default: 50)
# - level: filter by log level
# - since: ISO timestamp or relative time

Dashboard Features ​

Service Logs Section ​

  • Service Filter: View logs from specific services or all services
  • Level Filter: Show only errors, warnings, info, or debug logs
  • Search: Real-time text search through log messages
  • Live Stream: WebSocket-based real-time log updates
  • Auto-refresh: Periodic polling for new logs
  • Export: Download logs in JSON, CSV, or text format

Controls ​

  • Refresh: Manually update logs
  • Auto-Refresh: Toggle automatic updates every 3 seconds
  • Live Stream: Enable real-time WebSocket streaming
  • Export: Download filtered logs
  • Clear: Remove all logs (with confirmation)

Configuration ​

Log Levels ​

  • error: Critical errors and exceptions
  • warn: Warning messages and deprecations
  • info: General information and request logs
  • debug: Detailed debugging information

Time Filters ​

  • Relative: 1h, 30m, 2d, 1w
  • Absolute: ISO timestamps like 2025-11-05T10:00:00Z

Export Formats ​

  • JSON: Structured data with all fields
  • CSV: Comma-separated values for spreadsheets
  • TXT: Human-readable plain text format

Architecture ​

Storage ​

  • Daily log files: {service}/.logs/YYYY-MM-DD.log
  • JSON Lines format for easy parsing
  • Automatic rotation and cleanup

Real-time Updates ​

  • WebSocket connection for live streaming
  • File watching for follow mode in CLI
  • Periodic polling for auto-refresh

Performance ​

  • Efficient tail operations for large log files
  • Lazy loading and streaming for web interface
  • Configurable limits to prevent memory issues

Troubleshooting ​

No logs appearing ​

  1. Check if services are running and generating logs
  2. Verify .logs directory exists in service folders
  3. Check file permissions for log directories

Dashboard not updating ​

  1. Ensure WebSocket connection is established
  2. Check browser console for JavaScript errors
  3. Verify admin dashboard is running on correct port

Large log files ​

  • Log rotation happens automatically at 10MB
  • Use --tail option to limit output
  • Consider using --since for time-based filtering

Security Considerations ​

  • Log files are stored locally in service directories
  • No authentication required for local development
  • Production deployments should secure admin dashboard
  • Sensitive data should not be logged in production

This logging system provides comprehensive observability for your polyglot microservices while maintaining simplicity and performance.

MIT Licensed

© 2025 create-polyglot