Environment Variables

1// Type-safe environment configuration
2interface EnvConfig {
3  NODE_ENV: "development" | "production" | "test";
4  PORT: number;
5  DATABASE_URL: string;
6  API_KEY: string;
7  DEBUG: boolean;
8}
9 
10// Environment variable parser
11function getEnvString(key: string, defaultValue?: string): string {
12  const value = process.env[key];
13  if (value === undefined) {
14    if (defaultValue !== undefined) return defaultValue;
15    throw new Error(`Missing required environment variable: ${key}`);
16  }
17  return value;
18}
19 
20function getEnvNumber(key: string, defaultValue?: number): number {
21  const value = process.env[key];
22  if (value === undefined) {
23    if (defaultValue !== undefined) return defaultValue;
24    throw new Error(`Missing required environment variable: ${key}`);
25  }
26  const parsed = parseInt(value, 10);
27  if (isNaN(parsed)) {
28    throw new Error(`Environment variable ${key} must be a number`);
29  }
30  return parsed;
31}
32 
33function getEnvBoolean(key: string, defaultValue?: boolean): boolean {
34  const value = process.env[key];
35  if (value === undefined) {
36    if (defaultValue !== undefined) return defaultValue;
37    throw new Error(`Missing required environment variable: ${key}`);
38  }
39  return value.toLowerCase() === "true" || value === "1";
40}
41 
42// Load and validate configuration
43function loadConfig(): EnvConfig {
44  const nodeEnv = getEnvString("NODE_ENV", "development");
45 
46  if (!["development", "production", "test"].includes(nodeEnv)) {
47    throw new Error(`Invalid NODE_ENV: ${nodeEnv}`);
48  }
49 
50  return {
51    NODE_ENV: nodeEnv as EnvConfig["NODE_ENV"],
52    PORT: getEnvNumber("PORT", 3000),
53    DATABASE_URL: getEnvString("DATABASE_URL", "sqlite://local.db"),
54    API_KEY: getEnvString("API_KEY", "dev-key"),
55    DEBUG: getEnvBoolean("DEBUG", false),
56  };
57}
58 
59// Usage
60const config = loadConfig();
61 
62console.log("Configuration loaded:");
63console.log(`  Environment: ${config.NODE_ENV}`);
64console.log(`  Port: ${config.PORT}`);
65console.log(`  Database: ${config.DATABASE_URL}`);
66console.log(`  Debug mode: ${config.DEBUG}`);
67 
68// Export for use in other modules
69export { config, EnvConfig };