Implement Graceful rest application shutting down.

src/infrastructure/applications/rest/IRestAppModuleConfig.ts

@@ -7,4 +7,5 @@ export interface IRestAppModuleConfig extends IAppModuleConfig {
         allowMethods?: string[],
         allowHeaders?: string[],
     },
+    gracefulEnabled?: boolean,
 }

src/infrastructure/applications/rest/RestApplication.ts

@@ -123,6 +123,12 @@ export class RestApplication extends BaseApplication {
         this._app.use(urlencoded({ extended: true, limit: this._config.requestSizeLimit }));
     }
 
+    protected initGraceful() {
+        if (this._config.gracefulEnabled) {
+            this._app.enableShutdownHooks();
+        }
+    }
+
     public async init() {
         await super.init();
 
@@ -137,6 +143,7 @@ export class RestApplication extends BaseApplication {
         this.initSentry();
         this.initInterceptors();
         this.initSettings();
+        this.initGraceful();
     }
 
     public async start() {

src/infrastructure/applications/rest/config.ts

@@ -3,6 +3,8 @@ import baseConfig from '../base/config';
 import {IRestAppModuleConfig} from './IRestAppModuleConfig';
 import {ValidationExceptionFilterCustom} from './filters/ValidationExceptionFilterCustom';
 import {RequestExecutionExceptionFilter} from './filters/RequestExecutionExceptionFilter';
+import {GracefulController} from "./graceful/GracefulController";
+import {GracefulService} from "./graceful/GracefulService";
 
 export default {
     ...baseConfig,
@@ -17,6 +19,10 @@ export default {
                 provide: APP_FILTER,
                 useClass: RequestExecutionExceptionFilter,
             },
-        ],
+            config.gracefulEnabled && GracefulService,
+        ].filter(Boolean),
+        controllers: [
+            config.gracefulEnabled && GracefulController,
+        ].filter(Boolean),
     }),
 };

src/infrastructure/applications/rest/graceful/GracefulController.ts

@@ -0,0 +1,18 @@
+import {Controller, Get, InternalServerErrorException} from "@nestjs/common";
+import {GracefulService} from "./GracefulService";
+
+@Controller()
+export class GracefulController {
+    constructor(
+        public service: GracefulService
+    ) { }
+
+    @Get('health')
+    checkHealth() {
+        if (this.service.isShutdown) {
+            throw new InternalServerErrorException('Application is currently shutting down.');
+        }
+
+        return 'ok';
+    }
+}

src/infrastructure/applications/rest/graceful/GracefulService.ts

@@ -0,0 +1,18 @@
+import {BeforeApplicationShutdown} from "@nestjs/common";
+
+export class GracefulService implements BeforeApplicationShutdown {
+    public isShutdown = false;
+
+    async beforeApplicationShutdown(signal?: string) {
+        this.isShutdown = true;
+
+        if (process.env.K8S_READINESS_FAILURE_THRESHOLD && process.env.K8S_READINESS_PERIOD_SECONDS) {
+            const failureThreshold = parseInt(process.env.K8S_READINESS_FAILURE_THRESHOLD, 10);
+            const periodSeconds = parseInt(process.env.K8S_READINESS_PERIOD_SECONDS, 10);
+
+            await new Promise((resolve) => {
+                setTimeout(resolve, failureThreshold * periodSeconds * 1000);
+            });
+        }
+    }
+}