Deploying Angular app on Nginx is not sending Authorization header to Web Service

I am new to Angular and Docker. I am trying to deploy angular 6 app on Nginx in docker container. My angular app will call web-services with Authorization token. It works fine on my development env with --proxy-config but it does not work in docker container. I tried intercepting the HTTP request and update the URL of web service, but it is not send Authorization headers. How should I call web-services with custom headers?

environment.ts

export const environment = {
production: false,
calculateServiceAPIURL: 'http://localhost:8762'
};


import { Injectable } from '@angular/core';
import {
    HttpRequest,
    HttpHandler,
    HttpEvent,
    HttpInterceptor
} from '@angular/common/http';
import { Observable } from 'rxjs';
import { environment } from './../environments/environment';

@Injectable({
    providedIn: 'root'
})

export class TokeninceptorService implements HttpInterceptor {

constructor() { }

intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    console.log(req.headers);
    req = req.clone({
        url: environment.calculateServiceAPIURL + req.url,
        setHeaders: {
            'Content-Type': 'application/json',
            Authorization: 'Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzUxMiJ9.eyJzdWIiOiJtYWxhdi5wYXJpa2hAeWFob28uY29tIiwidXNlciI6IntcImlkXCI6MSxcImVtYWlsXCI6XCJtYWxhdi5wYXJpa2hAeWFob28uY29tXCIs'
        }
    });
    return next.handle(req);
}

}

Error Message: Access to XMLHttpRequest at 'http://localhost:8762/binaryTree/calculateSum' from origin 'http://localhost:4200' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: It does not have HTTP ok status.

Request and Response headers

Server is not receiving Authorization header due to which it is responding with 401 Unauthorized response status.