refactor: ♻️ Create a ConfigModule that exposes a ConfigService which loads the appropriate .env file

.env.sample

@@ -1,8 +1,11 @@
-GATEWAY_HOST=localhost
+GATEWAY_HOST=http://localhost
 GATEWAY_PORT=3333
 
-USER_HOST=localhost
+USER_HOST=http://localhost
 USER_PORT=15001
 
-TASK_HOST=localhost
-TASK_PORT=15002
+TASK_HOST=http://localhost
+TASK_PORT=15002
+
+DATABASE_USER=test
+DATABASE_PASSWORD=test

apps/gateway/src/app/app.module.ts

@@ -1,20 +1,38 @@
 import { IntrospectAndCompose } from '@apollo/gateway';
+import { gatewayConfig, userAppConfig } from '@libs/config';
 import { ApolloGatewayDriver, ApolloGatewayDriverConfig } from '@nestjs/apollo';
 import { Module } from '@nestjs/common';
+import { ConfigModule, ConfigService } from '@nestjs/config';
 import { GraphQLModule } from '@nestjs/graphql';
-import { subgraphsConfig } from '@graphql-federation-workspace/applications-config';
 
 import { AppController } from './app.controller';
 import { AppService } from './app.service';
 
 @Module({
   imports: [
-    GraphQLModule.forRoot<ApolloGatewayDriverConfig>({
+    ConfigModule.forRoot({
+      isGlobal: true,
+      load: [gatewayConfig, userAppConfig],
+    }),
+    GraphQLModule.forRootAsync<ApolloGatewayDriverConfig>({
+      imports: [ConfigModule],
+      inject: [ConfigService],
       driver: ApolloGatewayDriver,
-      gateway: {
-        supergraphSdl: new IntrospectAndCompose({
-          subgraphs: subgraphsConfig,
-        }),
+      useFactory: (configService: ConfigService) => {
+        const userAppConfig = configService.get('userApp');
+        return {
+          driver: ApolloGatewayDriver,
+          gateway: {
+            supergraphSdl: new IntrospectAndCompose({
+              subgraphs: [
+                {
+                  name: userAppConfig.name,
+                  url: `${userAppConfig.host}:${userAppConfig.port}/graphql`,
+                },
+              ],
+            }),
+          },
+        };
       },
     }),
   ],

apps/gateway/src/main.ts

@@ -4,17 +4,21 @@
  */
 
 import { Logger } from '@nestjs/common';
+import { ConfigService } from '@nestjs/config';
 import { NestFactory } from '@nestjs/core';
-import { gatewayConfig } from '@graphql-federation-workspace/applications-config';
 
 import { AppModule } from './app/app.module';
 
 async function bootstrap() {
   const app = await NestFactory.create(AppModule);
-  const port = gatewayConfig.port;
+
+  const configService = app.get(ConfigService);
+  const config = configService.get('gateway');
+  const host = config.host;
+  const port = config.port;
 
   await app.listen(port);
-  Logger.log(`🚀 Application is running on: ${gatewayConfig.host}:${port}`);
+  Logger.log(`🚀 Application is running on: ${host}:${port}`);
 }
 
 bootstrap();

apps/users-application/src/app/app.module.ts

@@ -1,11 +1,19 @@
+import { userAppConfig } from '@libs/config';
 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';
 
 @Module({
-  imports: [UsersModule],
+  imports: [
+    ConfigModule.forRoot({
+      isGlobal: true,
+      load: [userAppConfig],
+    }),
+    UsersModule,
+  ],
   controllers: [AppController],
   providers: [AppService],
 })

apps/users-application/src/main.ts

@@ -4,17 +4,21 @@
  */
 
 import { Logger } from '@nestjs/common';
+import { ConfigService } from '@nestjs/config';
 import { NestFactory } from '@nestjs/core';
-import { userSubGraph } from '@graphql-federation-workspace/applications-config';
 
 import { AppModule } from './app/app.module';
 
 async function bootstrap() {
   const app = await NestFactory.create(AppModule);
-  const port = userSubGraph.port;
+
+  const configService = app.get(ConfigService);
+  const config = configService.get('userApp');
+  const host = config.host;
+  const port = config.port;
 
   await app.listen(port);
-  Logger.log(`🚀 Application is running on: ${userSubGraph.host}:${port}`);
+  Logger.log(`🚀 Application is running on: ${host}:${port}`);
 }
 
 bootstrap();

libs/application-config/jest.config.ts → libs/config/jest.config.ts

@@ -1,10 +1,10 @@
 export default {
-  displayName: 'applications-config',
+  displayName: 'config',
   preset: '../../jest.preset.js',
   testEnvironment: 'node',
   transform: {
     '^.+\\.[tj]s$': ['ts-jest', { tsconfig: '<rootDir>/tsconfig.spec.json' }],
   },
   moduleFileExtensions: ['ts', 'js', 'html'],
-  coverageDirectory: '../../coverage/libs/application-config',
+  coverageDirectory: '../../coverage/libs/config',
 };

libs/config/project.json

@@ -0,0 +1,9 @@
+{
+  "name": "config",
+  "$schema": "../../node_modules/nx/schemas/project-schema.json",
+  "sourceRoot": "libs/config/src",
+  "projectType": "library",
+  "tags": [],
+  "// targets": "to see all targets run: nx show project config --web",
+  "targets": {}
+}

libs/config/src/index.ts

@@ -0,0 +1,2 @@
+export * from './lib/applications.config';
+export * from './lib/database.config';

libs/config/src/lib/applications.config.spec.ts

@@ -0,0 +1,41 @@
+import { gatewayConfig, userAppConfig } from './applications.config';
+
+describe('Config Tests', () => {
+  describe('gatewayConfig', () => {
+    it('should return default values when environment variables are not set', () => {
+      const config = gatewayConfig();
+      expect(config.host).toBe('http://localhost');
+      expect(config.port).toBe('3333');
+    });
+
+    it('should return environment values when environment variables are set', () => {
+      process.env['GATEWAY_HOST'] = 'http://gateway-host';
+      process.env['GATEWAY_PORT'] = '4000';
+      const config = gatewayConfig();
+      expect(config.host).toBe('http://gateway-host');
+      expect(config.port).toBe('4000');
+      delete process.env['GATEWAY_HOST'];
+      delete process.env['GATEWAY_PORT'];
+    });
+  });
+
+  describe('userAppConfig', () => {
+    it('should return default values when environment variables are not set', () => {
+      const config = userAppConfig();
+      expect(config.host).toBe('http://localhost');
+      expect(config.port).toBe('15001');
+      expect(config.name).toBe('user');
+    });
+
+    it('should return environment values when environment variables are set', () => {
+      process.env['USER_HOST'] = 'http://user-host';
+      process.env['USER_PORT'] = '5000';
+      const config = userAppConfig();
+      expect(config.host).toBe('http://user-host');
+      expect(config.port).toBe('5000');
+      expect(config.name).toBe('user');
+      delete process.env['USER_HOST'];
+      delete process.env['USER_PORT'];
+    });
+  });
+});

libs/config/src/lib/applications.config.ts

@@ -0,0 +1,20 @@
+import { registerAs } from '@nestjs/config';
+
+const DEFAULT_HOST = 'http://localhost';
+
+const DEFAULT_PORT = {
+  user: '15001',
+  task: '15002',
+  gateway: '3333',
+};
+
+export const gatewayConfig = registerAs('gateway', () => ({
+  host: process.env['GATEWAY_HOST'] ?? DEFAULT_HOST,
+  port: process.env['GATEWAY_PORT'] ?? DEFAULT_PORT.gateway,
+}));
+
+export const userAppConfig = registerAs('userApp', () => ({
+  host: process.env['USER_HOST'] ?? DEFAULT_HOST,
+  port: process.env['USER_PORT'] ?? DEFAULT_PORT.user,
+  name: 'user',
+}));