Using OpenIdConnect with AzureFunctions

Question

I'm using azure functions to host an API for a react app, however I'm also using the same azure function to host the html/js/css for the app (via proxy functions to static files on blob storage).

I have been using EasyAuth to provide authentication for it which has been working brilliantly, however I need to support a identity provider that isn't built into EasyAuth (and it doesn't support custom ones at all). This means I'm falling back to using the Microsoft.AspNetCore.Authentication.OpenIdConnect package.

I have registered the auth in my startup file

 builder.Services
            .AddAuthentication()
            .AddCookie("WebJobsAuthLevel") //errors without this, although I suspect it's wrong
            .AddCookie("Bearer") //errors without this, although I suspect it's wrong
            .AddOpenIdConnect("custom", o =>
            {
                o.MetadataAddress = "https://localhost:44320/.well-known/openid-configuration";
                o.ClientId = "clientid";
                o.ClientSecret = "secret";
                o.ResponseMode = OpenIdConnectResponseType.Code;
                o.SignInScheme = "Cookies";
                o.GetClaimsFromUserInfoEndpoint = true;
             });

along with a function that lets me trigger the challenge

    [FunctionName("CustomAuth")]
    public async Task<IActionResult?> Challenge([HttpTrigger(AuthorizationLevel.Anonymous, "get", "post", Route = ".auth/login/custom")]HttpRequest req, ILogger log)
    {
        return new ChallengeResult("custom");
    }

If i hit this function it works great, redirecting to the auth provider to login.

However once i login it redirects back to my function app which 404's

http://localhost:7071/signin-oidc?querystringhere

At this stage I'm guessing that AddAuthentication isn't able to hook into incoming web requests like it can when using it in asp.net mvc core. Wondering if there's a known way that I can hook this up, either at a lower level or via custom azure functions

Answer 1

Not the best solution but this nuget does the job until MS supports it. I have just tested and it works fine for me

https://github.com/kuromukira/azure-functions-jwt-validation-extension