[DSC-287] use CanActivateChild in order to check every time the rest server availability

src/app/app-routing.module.ts

@@ -36,7 +36,9 @@ import { ServerCheckGuard } from './core/server-check/server-check.guard';
     RouterModule.forRoot([
       { path: INTERNAL_SERVER_ERROR, component: ThemedPageInternalServerErrorComponent },
       {
-        path: '', canActivate: [ServerCheckGuard, AuthBlockingGuard],
+        path: '',
+        canActivate: [AuthBlockingGuard],
+        canActivateChild: [ServerCheckGuard],
         children: [
           { path: '', redirectTo: '/home', pathMatch: 'full' },
           {

src/app/core/server-check/server-check.guard.spec.ts

@@ -13,7 +13,8 @@ describe('ServerCheckGuard', () => {
   let rootDataServiceStub: SpyObj<RootDataService>;
 
   rootDataServiceStub = jasmine.createSpyObj('RootDataService', {
-    findRoot: jasmine.createSpy('findRoot')
+    findRoot: jasmine.createSpy('findRoot'),
+    invalidateRootCache: jasmine.createSpy('invalidateRootCache')
   });
   router = jasmine.createSpyObj('Router', {
     navigateByUrl: jasmine.createSpy('navigateByUrl')
@@ -37,10 +38,11 @@ describe('ServerCheckGuard', () => {
     });
 
     it('should not redirect to error page', () => {
-      guard.canActivate({} as any, {} as any).pipe(
+      guard.canActivateChild({} as any, {} as any).pipe(
         take(1)
       ).subscribe((canActivate: boolean) => {
         expect(canActivate).toEqual(true);
+        expect(rootDataServiceStub.invalidateRootCache).not.toHaveBeenCalled();
         expect(router.navigateByUrl).not.toHaveBeenCalled();
       });
     });
@@ -52,10 +54,11 @@ describe('ServerCheckGuard', () => {
     });
 
     it('should redirect to error page', () => {
-      guard.canActivate({} as any, {} as any).pipe(
+      guard.canActivateChild({} as any, {} as any).pipe(
         take(1)
       ).subscribe((canActivate: boolean) => {
         expect(canActivate).toEqual(false);
+        expect(rootDataServiceStub.invalidateRootCache).toHaveBeenCalled();
         expect(router.navigateByUrl).toHaveBeenCalledWith(getPageInternalServerErrorRoute());
       });
     });

src/app/core/server-check/server-check.guard.ts

@@ -1,5 +1,5 @@
 import { Injectable } from '@angular/core';
-import { ActivatedRouteSnapshot, CanActivate, Router, RouterStateSnapshot } from '@angular/router';
+import { ActivatedRouteSnapshot, CanActivateChild, Router, RouterStateSnapshot } from '@angular/router';
 
 import { Observable } from 'rxjs';
 import { map, tap } from 'rxjs/operators';
@@ -16,18 +16,18 @@ import { getFirstCompletedRemoteData } from '../shared/operators';
  * A guard that checks if root api endpoint is reachable.
  * If not redirect to 500 error page
  */
-export class ServerCheckGuard implements CanActivate {
+export class ServerCheckGuard implements CanActivateChild {
   constructor(private router: Router, private rootDataService: RootDataService) {
   }
 
   /**
    * True when root api endpoint is reachable.
    */
-  canActivate(
+  canActivateChild(
     route: ActivatedRouteSnapshot,
     state: RouterStateSnapshot): Observable<boolean> {
 
-    return this.rootDataService.findRoot().pipe(
+    return this.rootDataService.findRoot(false).pipe(
       getFirstCompletedRemoteData(),
       map((res: RemoteData<any>) => res.hasSucceeded),
       tap((hasSucceeded: boolean) => {