@empe/base-app

A foundation package providing common utilities, error handling, middleware, and environment management for Empe applications. This package standardizes core functionality across services in the Empe ecosystem.

Installation

npm install @empe/base-app
# or
yarn add @empe/base-app

Features

• Environment Management: Utilities for accessing and validating environment variables
• Error Handling: Standardized error classes and middleware
• Request Validation: Middleware for validating request parameters using Joi
• Logging: Integration with @empe/logger for consistent logging
• Rate Limiting: Configurable rate limiting for API endpoints
• Async Handling: Utilities for handling async Express routes

Usage

Environment Management

import { getHost, getPort, getNodeEnv } from '@empe/base-app/tools';

// Get environment variables with validation
const host = getHost(); // e.g., 'https://example.com'
const port = getPort(); // e.g., 3000
const nodeEnv = getNodeEnv(); // 'development', 'production', or 'test'

Logging

The base-app package provides a convenient wrapper around the @empe/logger package. The actual logger implementation is in the @empe/logger package, while base-app only provides a simplified createLogger function that injects environment variables:

// Implementation in base-app/tools/logger.ts
export const createLogger = (name: string) => createLoggerInstance(name, getNodeEnv(), getLogLevel(), getLogsDir());

This makes it easy to create a properly configured logger without manually handling environment variables:

import { createLogger } from '@empe/base-app/tools';

// Create a logger for your service
const logger = createLogger('MyService');

logger.info('Service starting');
logger.debug('Debug information', { userId: 123 });
logger.error('Error occurred', { error: new Error('Something went wrong') });

The logger automatically uses the appropriate environment variables (NODE_ENV, LOG_LEVEL, LOG_DIR) and applies consistent formatting across all services.

Error Handling

import { errorMiddleware } from '@empe/base-app/middlewares';
import { InvalidRequestError } from '@empe/base-app/errors';
import { createLogger } from '@empe/base-app/tools';

const logger = createLogger('MyService');
const app = express();

// Add routes
app.get('/resource/:id', (req, res) => {
    const { id } = req.params;
    if (!id) {
        throw new InvalidRequestError('ID is required');
    }
    // Process request
});

// Add error handling middleware
app.use(errorMiddleware(logger));

Request Validation

import { validateRequest } from '@empe/base-app/middlewares';
import Joi from 'joi';

const userSchema = Joi.object({
    name: Joi.string().required(),
    email: Joi.string().email().required(),
    age: Joi.number().integer().min(18).required(),
});

app.post('/users', validateRequest({ body: userSchema }), (req, res) => {
    // Request body is validated and typed
    const user = req.body;
    // Process user
    res.status(201).json(user);
});

Async Route Handling

import { asyncHandler } from '@empe/base-app/tools';

app.get(
    '/users/:id',
    asyncHandler(async (req, res) => {
        const user = await userService.findById(req.params.id);
        res.json(user);
        // No need for try/catch - errors are automatically passed to error middleware
    })
);

Rate Limiting

import { globalRateLimiter } from '@empe/base-app/middlewares';

// Apply rate limiting to all routes
app.use(globalRateLimiter);

// Or apply to specific routes
app.post('/login', globalRateLimiter, loginHandler);

Exports

The package provides the following export paths:

• @empe/base-app/tools - Environment utilities, logger, and async handlers
• @empe/base-app/errors - Error classes for different types of application errors
• @empe/base-app/middlewares - Express middleware for validation, error handling, and rate limiting
• @empe/base-app/schemas - Common Joi schemas for validation

License

MIT