Provide a setting to use a different REST url during SSR execution

config/config.example.yml

@@ -19,11 +19,32 @@ ui:
 
 # Angular Server Side Rendering (SSR) settings
 ssr:
+  # A boolean flag indicating whether the SSR configuration is enabled
+  # Defaults to true.
+  enabled: boolean;
+
+  # Enable request performance profiling data collection and printing the results in the server console.
+  # Defaults to false.
+  enablePerformanceProfiler: boolean;
+
   # Whether to tell Angular to inline "critical" styles into the server-side rendered HTML.
   # Determining which styles are critical is a relatively expensive operation; this option is
   # disabled (false) by default to boost server performance at the expense of loading smoothness.
   inlineCriticalCss: false
 
+  # Enable state transfer from the server-side application to the client-side application.
+  # Defaults to true.
+  # Note: When using an external application cache layer, it's recommended not to transfer the state to avoid caching it.
+  # Disabling it ensures that dynamic state information is not inadvertently cached, which can improve security and
+  # ensure that users always use the most up-to-date state.
+  transferState: boolean;
+
+  # When a different REST base URL is used for the server-side application, the generated state contains references to
+  # REST resources with the internal URL configured, so it is not transferred to the client application, by default.
+  # Enabling this setting transfers the state to the client application and replaces internal URLs with the public
+  # URLs used by the client application.
+  replaceRestUrl: boolean;
+
 # The REST API server settings
 # NOTE: these settings define which (publicly available) REST API to use. They are usually
 # 'synced' with the 'dspace.server.url' setting in your backend's local.cfg.
@@ -33,6 +54,9 @@ rest:
   port: 443
   # NOTE: Space is capitalized because 'namespace' is a reserved string in TypeScript
   nameSpace: /server
+  # Provide a different REST url to be used during SSR execution. It must contain the whole url including protocol, server port and
+  # server namespace (uncomment to use it).
+  #ssrBaseUrl: http://localhost:8080/server
 
 # Caching settings
 cache:

server.ts

@@ -81,6 +81,9 @@ let anonymousCache: LRU<string, any>;
 // extend environment with app config for server
 extendEnvironmentWithAppConfig(environment, appConfig);
 
+// The REST server base URL
+const REST_BASE_URL = environment.rest.ssrBaseUrl || environment.rest.baseUrl;
+
 // The Express app is exported so that it can be used by serverless Functions.
 export function app() {
 
@@ -156,7 +159,7 @@ export function app() {
    * Proxy the sitemaps
    */
   router.use('/sitemap**', createProxyMiddleware({
-    target: `${environment.rest.baseUrl}/sitemaps`,
+    target: `${REST_BASE_URL}/sitemaps`,
     pathRewrite: path => path.replace(environment.ui.nameSpace, '/'),
     changeOrigin: true,
   }));
@@ -165,7 +168,7 @@ export function app() {
    * Proxy the linksets
    */
   router.use('/signposting**', createProxyMiddleware({
-    target: `${environment.rest.baseUrl}`,
+    target: `${REST_BASE_URL}`,
     pathRewrite: path => path.replace(environment.ui.nameSpace, '/'),
     changeOrigin: true,
   }));
@@ -266,6 +269,11 @@ function serverSideRender(req, res, next, sendToUser: boolean = true) {
     })
     .then((html) => {
       if (hasValue(html)) {
+        // Replace REST URL with UI URL
+        if (environment.ssr.replaceRestUrl && REST_BASE_URL !== environment.rest.baseUrl) {
+          html = html.replace(new RegExp(REST_BASE_URL, 'g'), environment.rest.baseUrl);
+        }
+
         // save server side rendered page to cache (if any are enabled)
         saveToCache(req, html);
         if (sendToUser) {
@@ -623,7 +631,7 @@ function start() {
  * The callback function to serve health check requests
  */
 function healthCheck(req, res) {
-  const baseUrl = `${environment.rest.baseUrl}${environment.actuators.endpointPath}`;
+  const baseUrl = `${REST_BASE_URL}${environment.actuators.endpointPath}`;
   axios.get(baseUrl)
     .then((response) => {
       res.status(response.status).send(response.data);

src/app/app.config.ts

@@ -54,6 +54,7 @@ import {
 } from './app-routes';
 import { BROWSE_BY_DECORATOR_MAP } from './browse-by/browse-by-switcher/browse-by-decorator';
 import { AuthInterceptor } from './core/auth/auth.interceptor';
+import { DspaceRestInterceptor } from './core/dspace-rest/dspace-rest.interceptor';
 import { LocaleInterceptor } from './core/locale/locale.interceptor';
 import { LogInterceptor } from './core/log/log.interceptor';
 import {
@@ -148,6 +149,11 @@ export const commonAppConfig: ApplicationConfig = {
       useClass: LogInterceptor,
       multi: true,
     },
+    {
+      provide: HTTP_INTERCEPTORS,
+      useClass: DspaceRestInterceptor,
+      multi: true,
+    },
     // register the dynamic matcher used by form. MUST be provided by the app module
     ...DYNAMIC_MATCHER_PROVIDERS,
     provideCore(),

src/app/core/dspace-rest/dspace-rest.interceptor.spec.ts

@@ -0,0 +1,194 @@
+import {
+  HTTP_INTERCEPTORS,
+  HttpClient,
+} from '@angular/common/http';
+import {
+  HttpClientTestingModule,
+  HttpTestingController,
+} from '@angular/common/http/testing';
+import { PLATFORM_ID } from '@angular/core';
+import { TestBed } from '@angular/core/testing';
+
+import {
+  APP_CONFIG,
+  AppConfig,
+} from '../../../config/app-config.interface';
+import { DspaceRestInterceptor } from './dspace-rest.interceptor';
+import { DspaceRestService } from './dspace-rest.service';
+
+describe('DspaceRestInterceptor', () => {
+  let httpMock: HttpTestingController;
+  let httpClient: HttpClient;
+  const appConfig: Partial<AppConfig> = {
+    rest: {
+      ssl: false,
+      host: 'localhost',
+      port: 8080,
+      nameSpace: '/server',
+      baseUrl: 'http://api.example.com/server',
+    },
+  };
+  const appConfigWithSSR: Partial<AppConfig> = {
+    rest: {
+      ssl: false,
+      host: 'localhost',
+      port: 8080,
+      nameSpace: '/server',
+      baseUrl: 'http://api.example.com/server',
+      ssrBaseUrl: 'http://ssr.example.com/server',
+    },
+  };
+
+  describe('When SSR base URL is not set ', () => {
+    describe('and it\'s in the browser', () => {
+      beforeEach(() => {
+        TestBed.configureTestingModule({
+          imports: [HttpClientTestingModule],
+          providers: [
+            DspaceRestService,
+            {
+              provide: HTTP_INTERCEPTORS,
+              useClass: DspaceRestInterceptor,
+              multi: true,
+            },
+            { provide: APP_CONFIG, useValue: appConfig },
+            { provide: PLATFORM_ID, useValue: 'browser' },
+          ],
+        });
+
+        httpMock = TestBed.inject(HttpTestingController);
+        httpClient = TestBed.inject(HttpClient);
+      });
+
+      it('should not modify the request', () => {
+        const url = 'http://api.example.com/server/items';
+        httpClient.get(url).subscribe((response) => {
+          expect(response).toBeTruthy();
+        });
+
+        const req = httpMock.expectOne(url);
+        expect(req.request.url).toBe(url);
+        req.flush({});
+        httpMock.verify();
+      });
+    });
+
+    describe('and it\'s in SSR mode', () => {
+      beforeEach(() => {
+        TestBed.configureTestingModule({
+          imports: [HttpClientTestingModule],
+          providers: [
+            DspaceRestService,
+            {
+              provide: HTTP_INTERCEPTORS,
+              useClass: DspaceRestInterceptor,
+              multi: true,
+            },
+            { provide: APP_CONFIG, useValue: appConfig },
+            { provide: PLATFORM_ID, useValue: 'server' },
+          ],
+        });
+
+        httpMock = TestBed.inject(HttpTestingController);
+        httpClient = TestBed.inject(HttpClient);
+      });
+
+      it('should not replace the base URL', () => {
+        const url = 'http://api.example.com/server/items';
+
+        httpClient.get(url).subscribe((response) => {
+          expect(response).toBeTruthy();
+        });
+
+        const req = httpMock.expectOne(url);
+        expect(req.request.url).toBe(url);
+        req.flush({});
+        httpMock.verify();
+      });
+    });
+  });
+
+  describe('When SSR base URL is set ', () => {
+    describe('and it\'s in the browser', () => {
+      beforeEach(() => {
+        TestBed.configureTestingModule({
+          imports: [HttpClientTestingModule],
+          providers: [
+            DspaceRestService,
+            {
+              provide: HTTP_INTERCEPTORS,
+              useClass: DspaceRestInterceptor,
+              multi: true,
+            },
+            { provide: APP_CONFIG, useValue: appConfigWithSSR },
+            { provide: PLATFORM_ID, useValue: 'browser' },
+          ],
+        });
+
+        httpMock = TestBed.inject(HttpTestingController);
+        httpClient = TestBed.inject(HttpClient);
+      });
+
+      it('should not modify the request', () => {
+        const url = 'http://api.example.com/server/items';
+        httpClient.get(url).subscribe((response) => {
+          expect(response).toBeTruthy();
+        });
+
+        const req = httpMock.expectOne(url);
+        expect(req.request.url).toBe(url);
+        req.flush({});
+        httpMock.verify();
+      });
+    });
+
+    describe('and it\'s in SSR mode', () => {
+      beforeEach(() => {
+        TestBed.configureTestingModule({
+          imports: [HttpClientTestingModule],
+          providers: [
+            DspaceRestService,
+            {
+              provide: HTTP_INTERCEPTORS,
+              useClass: DspaceRestInterceptor,
+              multi: true,
+            },
+            { provide: APP_CONFIG, useValue: appConfigWithSSR },
+            { provide: PLATFORM_ID, useValue: 'server' },
+          ],
+        });
+
+        httpMock = TestBed.inject(HttpTestingController);
+        httpClient = TestBed.inject(HttpClient);
+      });
+
+      it('should replace the base URL', () => {
+        const url = 'http://api.example.com/server/items';
+        const ssrBaseUrl = appConfigWithSSR.rest.ssrBaseUrl;
+
+        httpClient.get(url).subscribe((response) => {
+          expect(response).toBeTruthy();
+        });
+
+        const req = httpMock.expectOne(ssrBaseUrl + '/items');
+        expect(req.request.url).toBe(ssrBaseUrl + '/items');
+        req.flush({});
+        httpMock.verify();
+      });
+
+      it('should not replace any query param containing the base URL', () => {
+        const url = 'http://api.example.com/server/items?url=http://api.example.com/server/item/1';
+        const ssrBaseUrl = appConfigWithSSR.rest.ssrBaseUrl;
+
+        httpClient.get(url).subscribe((response) => {
+          expect(response).toBeTruthy();
+        });
+
+        const req = httpMock.expectOne(ssrBaseUrl + '/items?url=http://api.example.com/server/item/1');
+        expect(req.request.url).toBe(ssrBaseUrl + '/items?url=http://api.example.com/server/item/1');
+        req.flush({});
+        httpMock.verify();
+      });
+    });
+  });
+});

src/app/core/dspace-rest/dspace-rest.interceptor.ts

@@ -0,0 +1,52 @@
+import { isPlatformBrowser } from '@angular/common';
+import {
+  HttpEvent,
+  HttpHandler,
+  HttpInterceptor,
+  HttpRequest,
+} from '@angular/common/http';
+import {
+  Inject,
+  Injectable,
+  PLATFORM_ID,
+} from '@angular/core';
+import { Observable } from 'rxjs';
+
+import {
+  APP_CONFIG,
+  AppConfig,
+} from '../../../config/app-config.interface';
+import { isEmpty } from '../../shared/empty.util';
+
+@Injectable()
+/**
+ * This Interceptor is used to use the configured base URL for the request made during SSR execution
+ */
+export class DspaceRestInterceptor implements HttpInterceptor {
+
+  /**
+   * Contains the configured application base URL
+   * @protected
+   */
+  protected baseUrl: string;
+  protected ssrBaseUrl: string;
+
+  constructor(
+    @Inject(APP_CONFIG) protected appConfig: AppConfig,
+    @Inject(PLATFORM_ID) private platformId: string,
+  ) {
+    this.baseUrl = this.appConfig.rest.baseUrl;
+    this.ssrBaseUrl = this.appConfig.rest.ssrBaseUrl;
+  }
+
+  intercept(request: HttpRequest<unknown>, next: HttpHandler): Observable<HttpEvent<unknown>> {
+    if (isPlatformBrowser(this.platformId) || isEmpty(this.ssrBaseUrl) || this.baseUrl === this.ssrBaseUrl) {
+      return next.handle(request);
+    }
+
+    // Different SSR Base URL specified so replace it in the current request url
+    const url = request.url.replace(this.baseUrl, this.ssrBaseUrl);
+    const newRequest: HttpRequest<any> = request.clone({ url });
+    return next.handle(newRequest);
+  }
+}

src/app/core/services/server-hard-redirect.service.spec.ts

@@ -1,13 +1,14 @@
 import { TestBed } from '@angular/core/testing';
 
+import { environment } from '../../../environments/environment.test';
 import { ServerHardRedirectService } from './server-hard-redirect.service';
 
 describe('ServerHardRedirectService', () => {
 
   const mockRequest = jasmine.createSpyObj(['get']);
   const mockResponse = jasmine.createSpyObj(['redirect', 'end']);
 
-  const service: ServerHardRedirectService = new ServerHardRedirectService(mockRequest, mockResponse);
+  let service: ServerHardRedirectService = new ServerHardRedirectService(environment, mockRequest, mockResponse);
   const origin = 'https://test-host.com:4000';
 
   beforeEach(() => {
@@ -68,4 +69,23 @@ describe('ServerHardRedirectService', () => {
     });
   });
 
+  describe('when SSR base url is set', () => {
+    const redirect = 'https://private-url:4000/server/api/bitstreams/uuid';
+    const replacedUrl = 'https://public-url/server/api/bitstreams/uuid';
+    const environmentWithSSRUrl: any = { ...environment, ...{ ...environment.rest, rest: {
+      ssrBaseUrl: 'https://private-url:4000/server',
+      baseUrl: 'https://public-url/server',
+    } } };
+    service = new ServerHardRedirectService(environmentWithSSRUrl, mockRequest, mockResponse);
+
+    beforeEach(() => {
+      service.redirect(redirect);
+    });
+
+    it('should perform a 302 redirect', () => {
+      expect(mockResponse.redirect).toHaveBeenCalledWith(302, replacedUrl);
+      expect(mockResponse.end).toHaveBeenCalled();
+    });
+  });
+
 });