init user system with keycloak

src/app.module.ts

@@ -1,9 +1,50 @@
 import { Module } from '@nestjs/common';
+import { ConfigModule } from '@nestjs/config';
 import { AppController } from './app.controller';
 import { AppService } from './app.service';
+import { UsersModule } from './users/users.module';
+import { AuthModule } from './auth/auth.module';
 
+/**
+ * Validates required environment variables.
+ * Throws an error if any required variables are missing or invalid.
+ * Returns the validated config.
+ */
+function validateEnvironment(config: Record<string, any>): Record<string, any> {
+  const requiredVars = ['JWKS_URI', 'JWT_ISSUER', 'JWT_AUDIENCE'];
+
+  const missingVars = requiredVars.filter((varName) => !config[varName]);
+
+  if (missingVars.length > 0) {
+    throw new Error(
+      `Missing required environment variables: ${missingVars.join(', ')}`,
+    );
+  }
+
+  // Validate PORT if provided
+  if (config.PORT && isNaN(Number(config.PORT))) {
+    throw new Error('PORT must be a valid number');
+  }
+
+  return config;
+}
+
+/**
+ * Root Application Module
+ *
+ * Imports and configures all feature modules and global configuration.
+ */
 @Module({
-  imports: [],
+  imports: [
+    // Configure global environment variables with validation
+    ConfigModule.forRoot({
+      isGlobal: true, // Make ConfigService available throughout the app
+      envFilePath: '.env', // Load from .env file
+      validate: validateEnvironment, // Validate required environment variables
+    }),
+    UsersModule,
+    AuthModule,
+  ],
   controllers: [AppController],
   providers: [AppService],
 })