Blazor Web App: Authentication Redirect URI is not HTTPS

.NET 9 is finally out and I was playing around with Blazor. I was setting up Authentication in a .NET 9 Blazor Web App. The authentication is configured with AzureAD, and locally everything was working fine. The application was running on HTTPS and the redirect_uri was HTTPS too.  

When the application was deployed to Azure, the Authentication was failing, because the redirect_uri was HTTP.  In Azure AD App Registration I configured it with HTTPS (HTTP is allowed only when using localhost). The application was running inside a Linux Container in an Azure Web App.

In order for redirect_uri to be HTTPS, I had to do the following:

1. Enable UseForwardedHeaders

WebApplicationBuilder builder = WebApplication.CreateBuilder(args);
 
builder.Services.Configure<ForwardedHeadersOptions>(options =>
{
    options.ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto;
});
// Other service registrations
 
WebApplication app = builder.Build();
 
// Note: Forwarded Headers Middleware should run before other middleware. 
// This ordering ensures that the middleware relying on forwarded headers information can consume the header values for processing. 
// Forwarded Headers Middleware can run after diagnostics and error handling, but it MUST BE RUN before calling UseHsts
app.UseForwardedHeaders();
 
if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Error", createScopeForErrors: true);
    app.UseHsts();
}
 
app.UseHttpsRedirection();
// Other middleware
 
app.Run();

2. Add the following app setting in Azure (More: Forward the scheme for Linux and non-IIS reverse proxies)

{
  "name": "ASPNETCORE_FORWARDEDHEADERS_ENABLED",
  "value": "true",
  "slotSetting": false
}

And that did it.

Hope this helps.

Happy Coding.

Regards,
Jaliya