feat(): support for async configuration in load

lib/config.module.ts

@@ -53,7 +53,7 @@ export class ConfigModule {
    * Also, registers custom configurations globally.
    * @param options
    */
-  static forRoot(options: ConfigModuleOptions = {}): DynamicModule {
+  static async forRoot(options: ConfigModuleOptions = {}): Promise<DynamicModule> {
     const envFilePaths = Array.isArray(options.envFilePath)
       ? options.envFilePath
       : [options.envFilePath || resolve(process.cwd(), '.env')];
@@ -88,7 +88,8 @@ export class ConfigModule {
     }
 
     const isConfigToLoad = options.load && options.load.length;
-    const providers = (options.load || [])
+    const configFactory = options.load ? await Promise.all(options.load.map((configFactory) => configFactory)) : [];
+    const providers = configFactory
       .map(factory =>
         createConfigProvider(factory as ConfigFactory & ConfigFactoryKeyHost),
       )

lib/interfaces/config-module-options.interface.ts

@@ -57,7 +57,7 @@ export interface ConfigModuleOptions {
    * Array of custom configuration files to be loaded.
    * See: https://docs.nestjs.com/techniques/configuration
    */
-  load?: Array<ConfigFactory>;
+  load?: Array<ConfigFactory | Promise<ConfigFactory>>;
 
   /**
    * A boolean value indicating the use of expanded variables, or object

tests/e2e/load-files-async.spec.ts

@@ -0,0 +1,31 @@
+import { INestApplication } from '@nestjs/common';
+import { Test } from '@nestjs/testing';
+import { AppModule } from '../src/app.module';
+
+describe('Async Files', () => {
+  let app: INestApplication;
+
+  beforeEach(async () => {
+    const module = await Test.createTestingModule({
+      imports: [AppModule.withLoadedAsyncConfigurations()],
+    }).compile();
+
+    app = module.createNestApplication();
+    await app.init();
+  });
+
+  it(`should return loaded configuration`, () => {
+    const host = app.get(AppModule).getDatabaseHost();
+    expect(host).toEqual('host');
+  });
+
+  it(`should return loaded configuration (injected through constructor)`, () => {
+    const config = app.get(AppModule).getDatabaseConfig();
+    expect(config.host).toEqual('host');
+    expect(config.port).toEqual(4000);
+  });
+
+  afterEach(async () => {
+    await app.close();
+  });
+});

tests/src/app.module.ts

@@ -140,6 +140,17 @@ export class AppModule {
     };
   }
 
+  static withLoadedAsyncConfigurations() {
+    return {
+      module: AppModule,
+      imports: [
+        ConfigModule.forRoot({
+          load: [Promise.resolve(databaseConfig)],
+        }),
+      ],
+    };
+  }
+
   static withNestedLoadedConfigurations(): DynamicModule {
     return {
       module: AppModule,