Example interceptor for apollo-angular

apollo.interceptor.ts

import { Injectable } from '@angular/core';
import { HttpHandler, HttpInterceptor, HttpRequest } from '@angular/common/http';
import { filter, switchMap } from 'rxjs/operators';

@Injectable()
export class ApolloInterceptor implements HttpInterceptor {

  constructor(private myAuthService: AuthService) {
  }

  intercept(req: HttpRequest<any>, next: HttpHandler) {
    // Filter your endpoint in order to only edit the graphql-related requests
    if (req.url.indexOf('/graphql') > -1) {
      // Get your jwt from your usual source, can be a facade, a service, or even sync data like localStorage
      return this.myAuthService.jwt$
        .pipe(
          // Make sure the request won't replay when your token gets updated
          first(),
          switchMap(idToken => {
            // Simply add the Authorization header to the request
            const clone = req.clone({
              setHeaders: {
                Authorization: `Bearer ${idToken.token}`
              }
            });
            // And you're done !
            return next.handle(clone);
          })
        );
    }
    // If it's not a graphql request, just give it to the next handler.
    return next.handle(req);
  }
}