feat(backend): introduce NestJS libraries and implement config library

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

@@ -2,16 +2,11 @@ import { Module } from '@nestjs/common';
 import { AppController } from './app.controller';
 import { ClientProxyFactory } from '@nestjs/microservices';
 import gatewayConfiguration from './config/configuration';
-import { ConfigModule, ConfigService } from '@nestjs/config';
+import { ConfigService } from '@nestjs/config';
+import { ConfigModule } from '@app/config';
 
 @Module({
-  imports: [
-    ConfigModule.forRoot({
-      load: [gatewayConfiguration],
-      ignoreEnvFile: ['staging', 'production'].includes(process.env.NODE_ENV),
-      envFilePath: process.env.NODE_ENV === 'test' ? '.env.test' : '.env',
-    }),
-  ],
+  imports: [ConfigModule.loadConfiguration(gatewayConfiguration)],
   controllers: [AppController],
   providers: [
     {

backend/apps/gateway/test/jest-e2e.json

@@ -5,5 +5,8 @@
   "testRegex": ".e2e-spec.ts$",
   "transform": {
     "^.+\\.(t|j)s$": "ts-jest"
+  },
+  "moduleNameMapper": {
+    "^@app/config(|/.*)$": "<rootDir>/../../../libs/config/src/$1"
   }
 }

backend/apps/question/src/question.module.ts

@@ -1,16 +1,11 @@
 import { Module } from '@nestjs/common';
 import { QuestionController } from './question.controller';
 import { QuestionService } from './question.service';
-import { ConfigModule } from '@nestjs/config';
 import questionConfiguration from './config/configuration';
+import { ConfigModule } from '@app/config';
 
 @Module({
-  imports: [
-    ConfigModule.forRoot({
-      load: [questionConfiguration],
-      envFilePath: process.env.NODE_ENV === 'test' ? '.env.test' : '.env',
-    }),
-  ],
+  imports: [ConfigModule.loadConfiguration(questionConfiguration)],
   controllers: [QuestionController],
   providers: [QuestionService],
 })

backend/libs/config/src/config.module.ts

@@ -0,0 +1,23 @@
+import { DynamicModule } from '@nestjs/common';
+import {
+  ConfigService,
+  ConfigModule as NestConfigModule,
+} from '@nestjs/config';
+
+export class ConfigModule extends NestConfigModule {
+  static loadConfiguration(configuration: () => object): DynamicModule {
+    return {
+      imports: [
+        NestConfigModule.forRoot({
+          load: [configuration],
+          ignoreEnvFile: ['staging', 'production'].includes(
+            process.env.NODE_ENV,
+          ),
+          envFilePath: process.env.NODE_ENV === 'test' ? '.env.test' : '.env',
+        }),
+      ],
+      module: ConfigModule,
+      providers: [ConfigService],
+    };
+  }
+}

backend/libs/config/src/index.ts

@@ -0,0 +1 @@
+export * from './config.module';

backend/libs/config/tsconfig.lib.json

@@ -0,0 +1,9 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "declaration": true,
+    "outDir": "../../dist/libs/config"
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "dist", "test", "**/*spec.ts"]
+}

backend/nest-cli.json

@@ -26,6 +26,15 @@
       "compilerOptions": {
         "tsConfigPath": "apps/question/tsconfig.app.json"
       }
+    },
+    "config": {
+      "type": "library",
+      "root": "libs/config",
+      "entryFile": "index",
+      "sourceRoot": "libs/config/src",
+      "compilerOptions": {
+        "tsConfigPath": "libs/config/tsconfig.lib.json"
+      }
     }
   }
 }

backend/package.json

@@ -60,22 +60,21 @@
       "json",
       "ts"
     ],
-    "rootDir": "src",
+    "rootDir": ".",
     "testRegex": ".*\\.spec\\.ts$",
     "transform": {
       "^.+\\.(t|j)s$": "ts-jest"
     },
     "collectCoverageFrom": [
       "**/*.(t|j)s"
     ],
-    "coverageDirectory": "../coverage",
     "testEnvironment": "node",
     "roots": [
       "<rootDir>/apps/",
       "<rootDir>/libs/"
     ],
     "moduleNameMapper": {
-      "^@app/utils-lib(|/.*)$": "<rootDir>/libs/utils-lib/src/$1"
+      "^@app/config(|/.*)$": "<rootDir>/libs/config/src/$1"
     }
   }
-}
+}

backend/tsconfig.json

@@ -23,6 +23,12 @@
       ],
       "@app/utils-lib/*": [
         "libs/utils-lib/src/*"
+      ],
+      "@app/config": [
+        "libs/config/src"
+      ],
+      "@app/config/*": [
+        "libs/config/src/*"
       ]
     }
   }