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

.env.sample

@@ -1,8 +1,13 @@
+PROTOCOL=http
+
 GATEWAY_HOST=localhost
 GATEWAY_PORT=3333
 
 USER_HOST=localhost
 USER_PORT=15001
 
 TASK_HOST=localhost
-TASK_PORT=15002
+TASK_PORT=15002
+
+DATABASE_HOST=127.0.0.1
+DATABASE_PORT=3306

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: `${userAppConfig.protocol}://${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;
 
-  await app.listen(port);
-  Logger.log(`🚀 Application is running on: ${gatewayConfig.host}:${port}`);
+  const configService = app.get(ConfigService);
+  const config = configService.get('gateway');
+
+  await app.listen(config.port);
+  Logger.log(
+    `🚀 Application is running on: ${config.protocol}://${config.host}:${config.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;
 
-  await app.listen(port);
-  Logger.log(`🚀 Application is running on: ${userSubGraph.host}:${port}`);
+  const configService = app.get(ConfigService);
+  const config = configService.get('userApp');
+
+  await app.listen(config.port);
+  Logger.log(
+    `    🚀 Application is running on: ${config.protocol}://${config.host}:${config.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 +1,61 @@
+import { gatewayConfig, userAppConfig } from './applications.config';
+
+describe('Config Tests', () => {
+  describe('gatewayConfig', () => {
+    it('should return default gateway config when no environment variables are set', () => {
+      const config = gatewayConfig();
+      expect(config).toEqual({
+        protocol: 'http',
+        host: 'localhost',
+        port: 3333,
+      });
+    });
+
+    it('should return gateway config with environment variables', () => {
+      process.env['PROTOCOL'] = 'https';
+      process.env['GATEWAY_HOST'] = 'gateway.example.com';
+      process.env['GATEWAY_PORT'] = '4444';
+
+      const config = gatewayConfig();
+      expect(config).toEqual({
+        protocol: 'https',
+        host: 'gateway.example.com',
+        port: 4444,
+      });
+
+      delete process.env['PROTOCOL'];
+      delete process.env['GATEWAY_HOST'];
+      delete process.env['GATEWAY_PORT'];
+    });
+  });
+
+  describe('userAppConfig', () => {
+    it('should return default user app config when no environment variables are set', () => {
+      const config = userAppConfig();
+      expect(config).toEqual({
+        protocol: 'http',
+        host: 'localhost',
+        port: 15001,
+        name: 'user',
+      });
+    });
+
+    it('should return user app config with environment variables', () => {
+      process.env['PROTOCOL'] = 'https';
+      process.env['USER_HOST'] = 'user.example.com';
+      process.env['USER_PORT'] = '5555';
+
+      const config = userAppConfig();
+      expect(config).toEqual({
+        protocol: 'https',
+        host: 'user.example.com',
+        port: 5555,
+        name: 'user',
+      });
+
+      delete process.env['PROTOCOL'];
+      delete process.env['USER_HOST'];
+      delete process.env['USER_PORT'];
+    });
+  });
+});