feat: implement environment configuration and validation

apps/api/.env.example

@@ -4,16 +4,21 @@ PORT=3000
 # JWT Authentication
 JWT_SECRET=your-super-secret-jwt-key-change-in-production
 
+# Database (PostgreSQL connection string)
+DATABASE_URL=postgresql://user:password@localhost:5432/stellar_pay
+
 # Stellar Network
 STELLAR_NETWORK=TESTNET
-STELLAR_HORIZON_URL=https://horizon-testnet.stellar.org
+STELLAR_RPC_URL=https://soroban-testnet.stellar.org
 
-# Treasury
+# Treasury (Stellar secret key - starts with 'S', 56 characters)
+TREASURY_PRIVATE_KEY=SXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 TREASURY_WALLET_ADDRESS=GDTREASURYADDRESSXXXXXX
 SUPPORTED_ASSETS=USDC,ARS
 
-# Database (for when implemented)
-DATABASE_URL=postgresql://user:password@localhost:5432/stellar_pay
+# Blockchain Node URLs
+BTC_NODE_URL=https://btc-node.example.com
+ETH_NODE_URL=https://eth-node.example.com
 
-# Redis (for when implemented)
+# Redis (for queue management)
 REDIS_URL=redis://localhost:6379

apps/api/package.json

@@ -21,6 +21,7 @@
   },
   "dependencies": {
     "@nestjs/common": "^11.0.1",
+    "@nestjs/config": "^4.0.3",
     "@nestjs/core": "^11.0.1",
     "@nestjs/passport": "^11.0.5",
     "@nestjs/platform-express": "^11.0.1",
@@ -32,7 +33,7 @@
     "@nestjs/swagger": "^11.2.6",
     "reflect-metadata": "^0.2.2",
     "rxjs": "^7.8.1",
-    "swagger-ui-express": "^5.0.1"
+    "zod": "^4.3.6"
   },
   "devDependencies": {
     "@eslint/eslintrc": "^3.2.0",

apps/api/src/app.module.ts

@@ -8,9 +8,15 @@ import { TreasuryModule } from './treasury/treasury.module';
 import { AuthModule } from './auth/auth.module';
 import { JwtAuthGuard } from './auth/guards/jwt-auth.guard';
 import { ThrottlerRedisGuard } from './rate-limiter/guards/throttler-redis.guard';
+import { ConfigModule } from '@nestjs/config';
+import { validate } from './config/env.validation';
 
 @Module({
   imports: [
+    ConfigModule.forRoot({
+      validate,
+      isGlobal: true,
+    }),
     HealthModule,
     TreasuryModule,
     AuthModule,

apps/api/src/config/env.validation.ts

@@ -0,0 +1,23 @@
+import { z } from 'zod';
+
+export const envSchema = z.object({
+  DATABASE_URL: z.string().url('DATABASE_URL must be a valid URL'),
+  JWT_SECRET: z.string().min(16, 'JWT_SECRET must be at least 16 characters long'),
+  TREASURY_PRIVATE_KEY: z.string().startsWith('S').length(56, 'TREASURY_PRIVATE_KEY must be a valid Stellar secret key (56 characters)'),
+  STELLAR_RPC_URL: z.string().url('STELLAR_RPC_URL must be a valid URL'),
+  BTC_NODE_URL: z.string().url('BTC_NODE_URL must be a valid URL'),
+  ETH_NODE_URL: z.string().url('ETH_NODE_URL must be a valid URL'),
+  REDIS_URL: z.string().url('REDIS_URL must be a valid URL'),
+  PORT: z.coerce.number().default(3000),
+});
+
+export function validate(config: Record<string, unknown>) {
+  const validatedConfig = envSchema.safeParse(config);
+
+  if (!validatedConfig.success) {
+    console.error('❌ Environment validation failed:', JSON.stringify(validatedConfig.error.format(), null, 2));
+    process.exit(1);
+  }
+
+  return validatedConfig.data;
+}