REACT application to call secure Azure WEBAPI Service - NO USERS

I have created a simple REACT application that is ONLY run on a local PC attached to a large screen on our network. Internal use only! It is like a billboard or dashboard. There is ZERO user interaction. The screen is NOT a touch screen and there is no keyboard and mouse attached. Therefore NO users to login.

The REACT application is build and then deployed to a folder on the PC. All automated. The initial deployment includes all current data. Then at windows startup a command something like this is executed: "python -m http.server 3000" (just example...)

The application has initial data that was deployed with the application, however, I would like it to also be able to call a secure Azure WebAPI service to get updated statistics every few minutes. Very small data. Mostly integer values. I just want to provide some real time updates.

I have the REACT app fully working (if the WEBAPI is not secure) or the individual calls allow anonymous. However, we have business rules that require all endpoints to be secure.

This app runs locally, but the API is an Azure App Service.

I have setup the REACT application in Azure AD as a registered application and configured it to have permissions to call the WEBAPI service.

I have many console applications that are setup and work basically the same way as this REACT application. With the C# daemon applications, there is a MSAL package that makes it easy.

I am trying to learn REACT, and instead of building this as another WPF or UWP application, I wanted to try using REACT.

So, I know I need an access token somehow. I was thinking with a client ID and Secret just like I do in my C# daemon clients that are written in C#.

I cannot find any REACT nor Angular examples that do this without a user login first. Remember, the PC does not have input devices. Display ONLY. Again, my app does not have users. It calls a secure API to get data. That's it.

Thanks for your help.

Using Joy Wang's comments and this page from documentation: Service-to-Service Access Token Request

This is my new code:

const adalConfig = {
  tenant: '...',
  clientId: '...',
  clientSecret: '...',
  authority: 'https://login.microsoftonline.com/{tenant}/oauth2/token',
  endpoints: {
    apiResourceId: 'api://bbbbbb-...',
  },
};

function getAccessToken() {
  var requestParams = {
    grant_type: 'client_credentials',
    client_id: adalConfig.clientId,
    client_secret: adalConfig.clientSecret,
    resource: adalConfig.endpoints.apiResourceId
  };

  // Make a request to the token issuing endpoint.
  fetch(adalConfig.authority,
    {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify( requestParams )
    }).then(response => {
      if (response.status >= 200 && response.status < 300) {
        console.log(response);
        console.log(response.json());
      } else {
        console.log('Somthing happened wrong');
        console.log(response);
      }
    }).catch(err => err);
}

When I call the function above, I get the following response:

Response {type: "cors", url: "https://login.microsoftonline.com/.../oauth2/token", redirected: false, status: 400, ok: false, …} body: (...) bodyUsed: false headers: Headers {} ok: false redirected: false status: 400 statusText: "Bad Request" type: "cors" url: "https://login.microsoftonline.com/.../oauth2/token" proto: Response

Maybe there is another way to start the REACT application so that CORS is not checked? Any ideas?

Thanks again.

So, currently there is not a secure way to do what I want. The basic issue is that you cannot use the client credential grant type from JavaScript in a browser.

However, I think I have a good work around that may help others. I am sure it is NOT for most application. And I believe OAUTH is working on a solution so this may not be needed in the near future. If a better solution is add, I will gladly mark it as the correct answer. Thanks for your help.

My app is basically an automated dashboard/billboard with ZERO user input. It pulls secure data and displays it. The REACT application is ONLY on a LOCAL PC on a wall with NO inputs. A script runs when the PC is turned on.

The script starts the built REACT application using an http server like python. Ex: "python -m http.server 8000"

The script then opens the browser in kiosk mode so the only thing you see on the screen is the application.

So far, this is exactly as I had it before.

WORK AROUND: I created a command line utility called GetToken. Before the REACT application is started by the script, it calls this utility like so: "gettoken --client Dashboard --file token.json" This utility makes the Client Credential Grant Type call to get a token. It then saved that token to a local json file with the other built REACT files. Ex: \public\data\token.json

In my REACT application, it just loads the token and uses it.

const t = await fetch('./data/token.json').then(r => r.json());
this.setState({ token: t.token });

Then I just add this to my api calls like so:

const fetchOptions = {
  method: 'GET',
  headers: {
    "Authorization": `Bearer ${this.state.token}`,
    "Content-Type": "application/json"
  }
};
const newSlides = await fetch(this.state.baseUrl + '/api/Dashboard/GetSlides', fetchOptions).then(response => response.json());

IMPORTANT: This only works if you also have the ability to update the API. If you cannot, then you will still get CORS errors. You will have to allow calls from the localhost and port you use to start you application. You should pick something other than 3000, 4200, or 8000.

I added the following to my API startup.cs:

public void ConfigureServices(IServiceCollection services) {
  ...

  var origins = Configuration.GetSection("AppSettings:AllowedOrigins").Value.Split(",");
  services.AddCors(o => o.AddPolicy(specificOriginsPolicy, builder => {
    builder.WithOrigins(origins)
      .AllowAnyMethod()
      .AllowAnyHeader()
      .AllowCredentials()
      .SetIsOriginAllowed((host) => true);
  }));

  ...
}

public void Configure(IApplicationBuilder app) {
  ...
  app.UseCors(specificOriginsPolicy);
  ...
}

I am still refining this solution, but it works well so far. I may turn the utility into a background service that is updating the token on an interval. Or I may turn the utility into a Shell, and then use it instead of the script. Either way, you get the idea.

LESSON: I know I could have done this as a UWP or WPF application and avoided all these issues, but the main goal was to learn REACT. I learned a lot. I would do it again. It is shocking just how little code there is to my REACT application now that it is done. I believe REACT could be used for many similar scenarios.