NGINX x-forwarded-proto not working

I had similar issue with hosting asp.net core app on debian server with nginx. I also thought that the issue is in nginx configuration but it was not...

Your nginx configuration looks good. The magic happens in this code:

app.UseForwardedHeaders(new ForwardedHeadersOptions
{
    ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto
});

This code reads the XForwardedFor and XForwardedProto headers and sets headers values to HttpContext properties like this:

• X-Forwarded-For to HttpContext.Connection.RemoteIpAddress
• X-Forwarded-Proto to HttpContext.Request.Scheme

Documentation is here https://learn.microsoft.com/en-us/aspnet/core/host-and-deploy/proxy-load-balancer?view=aspnetcore-8.0

If you want to verify, that nginx really provides X-Forwarded-For and X-Forwarded-Proto headers place a simple middleware before app.UseForwardedHeaders().

public void Configure(IApplicationBuilder app, IWebHostEnvironment env, ILogger<Startup> logger)
{
    //This will log all available headers in http request, your log MinimumLevel must be set to information
    app.Use(async (context, next) =>
    {
        var headers = context.Request.Headers.Select(x => new { x.Key, x.Value });

        logger.LogInformation("Headers: {@Headers}", headers);

        await next();
    });

    // this will read X-Forwarded-For and X-Forwarded-Proto headers and remove them from context.Request.Headers
    app.UseForwardedHeaders(new ForwardedHeadersOptions
    {
        ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto
    });
    
    // here you can see if the app.UseForwardedHeaders() works as expected
    app.Use(async (context, next) =>
    {
        var xForwardedForHeaderValue = context.Connection.RemoteIpAddress;

        var XForwardedProtoHeaderValue = context.Request.Scheme;

        logger.LogInformation("IP: {Ip}, scheme: {Scheme}", xForwardedForHeaderValue, XForwardedProtoHeaderValue);

        await next();
    });

    // the rest of your code
}