netrun-errors 1.1.0

Unified error handling for Netrun Systems FastAPI applications

netrun-errors

Unified error handling for Netrun Systems FastAPI applications.

Features

• Structured Error Responses: Consistent JSON error format across all services
• Automatic Correlation IDs: Request tracking with unique identifiers
• Machine-Readable Error Codes: Frontend-friendly error classification
• Global Exception Handlers: FastAPI integration with comprehensive error handling
• Request/Response Logging: Middleware with performance tracking
• Type Safety: Full typing support with mypy strict mode
• Comprehensive Testing: 90%+ test coverage

Installation

pip install netrun-errors

Quick Start

from fastapi import FastAPI
from netrun_errors import (
    install_exception_handlers,
    install_error_logging_middleware,
    InvalidCredentialsError,
    ResourceNotFoundError,
)

# Create FastAPI app
app = FastAPI()

# Install error handlers and middleware
install_exception_handlers(app)
install_error_logging_middleware(app)

# Use exceptions in your routes
@app.get("/users/{user_id}")
async def get_user(user_id: str):
    if user_id == "999":
        raise ResourceNotFoundError(
            resource_type="User",
            resource_id=user_id
        )
    return {"user_id": user_id}

@app.post("/auth/login")
async def login(email: str, password: str):
    if not validate_credentials(email, password):
        raise InvalidCredentialsError()
    return {"token": "..."}

Error Response Format

All errors return structured JSON responses:

{
    "error": {
        "code": "AUTH_INVALID_CREDENTIALS",
        "message": "Invalid email or password",
        "details": {},
        "correlation_id": "req-20251125-143210-a8f3c9",
        "timestamp": "2025-11-25T14:32:10.523Z",
        "path": "/api/v1/auth/login"
    }
}

Available Exceptions

Authentication (401 Unauthorized)

• InvalidCredentialsError: Invalid email/password combination
• TokenExpiredError: Authentication token has expired
• TokenInvalidError: Malformed or invalid token
• TokenRevokedError: Token has been explicitly revoked
• AuthenticationRequiredError: Endpoint requires authentication

from netrun_errors import InvalidCredentialsError, TokenExpiredError

# Example usage
raise InvalidCredentialsError()
raise TokenExpiredError(message="Your session has expired")

Authorization (403 Forbidden)

• InsufficientPermissionsError: User lacks required permissions
• TenantAccessDeniedError: Cross-tenant access attempt

from netrun_errors import InsufficientPermissionsError, TenantAccessDeniedError

# Example usage
raise InsufficientPermissionsError(
    message="You need admin role to perform this action",
    details={"required_role": "admin", "user_role": "member"}
)

raise TenantAccessDeniedError(
    details={"user_tenant_id": "123", "resource_tenant_id": "456"}
)

Resource (404 Not Found, 409 Conflict)

• ResourceNotFoundError: Requested resource does not exist
• ResourceConflictError: Operation conflicts with existing state

from netrun_errors import ResourceNotFoundError, ResourceConflictError

# Example usage
raise ResourceNotFoundError(
    resource_type="Product",
    resource_id="SKU-12345"
)

raise ResourceConflictError(
    message="Email address already registered",
    details={"email": "[e-mail]"}
)

Service (503 Service Unavailable)

• ServiceUnavailableError: Service or dependency unavailable
• TemporalUnavailableError: Workflow engine unavailable

from netrun_errors import ServiceUnavailableError, TemporalUnavailableError

# Example usage
raise ServiceUnavailableError(
    message="Database connection failed",
    details={"retry_after": 30}
)

raise TemporalUnavailableError(
    message="Unable to start workflow",
    details={"workflow_id": "user-onboarding-123"}
)

Correlation IDs

Every exception automatically generates a unique correlation ID for request tracking:

from netrun_errors import ResourceNotFoundError

try:
    raise ResourceNotFoundError(resource_type="User", resource_id="123")
except ResourceNotFoundError as exc:
    print(exc.correlation_id)  # req-20251125-143210-a8f3c9

Correlation IDs are also:

• Injected into response headers as X-Correlation-ID
• Available in request state for logging: request.state.correlation_id
• Included in all log messages for distributed tracing

Custom Details

Add context-specific information to error responses:

from netrun_errors import InvalidCredentialsError

raise InvalidCredentialsError(
    message="Invalid credentials",
    details={
        "attempt_number": 3,
        "max_attempts": 5,
        "lockout_duration": 300,
    }
)

Global Exception Handlers

The install_exception_handlers() function registers handlers for:

• NetrunException: All custom Netrun exceptions
• RequestValidationError: FastAPI validation errors
• HTTPException: Generic HTTP exceptions
• Exception: Unhandled exceptions (500 errors)

All handlers return consistent JSON format with correlation IDs.

Error Logging Middleware

The install_error_logging_middleware() function provides:

• Request/response logging: Structured logs with correlation IDs
• Performance tracking: Duration measurement for all requests
• Automatic correlation ID injection: Available in request.state.correlation_id
• Exception logging: Full traceback logging for errors

from fastapi import FastAPI, Request
from netrun_errors import install_error_logging_middleware
import logging

app = FastAPI()
install_error_logging_middleware(app)

# Configure logging
logging.basicConfig(
    level=logging.INFO,
    format='%(asctime)s - %(name)s - %(levelname)s - %(message)s'
)

@app.get("/example")
async def example(request: Request):
    # Access correlation ID
    correlation_id = request.state.correlation_id
    logger.info(f"Processing request: {correlation_id}")
    return {"status": "ok"}

Development

Setup

# Clone repository
git clone https://github.com/netrun-systems/netrun-errors.git
cd netrun-errors

# Install development dependencies
pip install -e ".[dev]"

Testing

# Run tests with coverage
pytest

# Run tests with verbose output
pytest -v

# Run specific test file
pytest tests/test_exceptions.py

# Generate HTML coverage report
pytest --cov-report=html

Code Quality

# Format code with black
black netrun_errors tests

# Lint with ruff
ruff check netrun_errors tests

# Type check with mypy
mypy netrun_errors

License

MIT License - see LICENSE file for details

Contributing

Contributions welcome! Please submit pull requests to the main repository.

Support

For issues, questions, or feature requests, please contact:

• Email: [e-mail]
• Website: https://www.netrunsystems.com

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Version: 1.0.0 Author: Netrun Systems Python: 3.11+ Framework: FastAPI 0.115+