How to implement SSO using an angular 6+ nodejs - node.js

Question

I want to implement Single sign-on, but I don't quite understand how to do it. That's what I have at the moment. In fact, I have no mistakes. It's just that Single Sign-on is not working, in both clients I have to log in both times, although the server is one. I use Angular 6 nodejs (express)
token.interceptor.ts:
import { Injectable } from "#angular/core";
import { AuthService } from "../services/auth.service";
import { HttpInterceptor, HttpRequest, HttpHandler, HttpEvent, HttpErrorResponse } from "#angular/common/http";
import { Observable, throwError } from "rxjs";
import { catchError } from "rxjs/operators";
import { Router } from "#angular/router";
#Injectable()
export class TokenInterceptor implements HttpInterceptor {
constructor(private auth: AuthService, private router: Router){
}
intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
if (this.auth.isAuthenticated()) {
req = req.clone({
setHeaders: {
Authorization: this.auth.getToken()
}
})
}
return next.handle(req).pipe(
catchError(
(error: HttpErrorResponse) => this.handleAuthError(error)
)
)
}
private handleAuthError(error: HttpErrorResponse): Observable<any> {
if (error.status === 401) {
this.router.navigate(['/login']), {
queryParams: {
sessionFailed: true
}
}
}
return throwError(error)
}
}
app.component.ts:
import { Component, OnInit } from '#angular/core';
import { AuthService } from './shared/services/auth.service';
#Component({
selector: 'app-root',
template: '<router-outlet></router-outlet>'
})
export class AppComponent implements OnInit {
constructor(private auth: AuthService) {}
ngOnInit() {
const potentialToken = localStorage.getItem('auth-token')
if (potentialToken !== null) {
this.auth.setToken(potentialToken)
}
}
}
authService:
import { Injectable } from "#angular/core";
import { HttpClient } from "#angular/common/http";
import { Observable } from "rxjs";
import { tap } from "rxjs/operators";
import { User } from "../interfaces";
#Injectable({
providedIn: 'root'
})
export class AuthService {
private token = null;
constructor(private http: HttpClient) {
}
login(user: User): Observable<{token: string}> {
return this.http.post<{token: string}>('/api/auth/login', user)
.pipe(
tap(
({token}) => {
localStorage.setItem('auth-token', token)
this.setToken(token)
}
)
)
}
setToken(token: string) {
this.token = token
}
getToken(): string {
return this.token
}
isAuthenticated(): boolean {
return !!this.token
}
logout() {
this.setToken(null)
localStorage.clear()
}
}