aspnetcore 2.2 docker image behind a HTTPS proxy

[Szadegan]

Hi,
I am trying to run a docker image on a Debian9 server which is also an Apache server. The WebApp which is located in the docker, will be reached via a HTTPS proxy serever. Which meansThe HTTPS requests comes to the proxy and then they ends there and the HTTP requests should be sent to Apache server which is redirecting to the docker.
Issue:
The issue is when I try to open the web page via browser it returns a 502 bad Gateway and cannot find anything which leads me to the issue.
The app needs to authenticate via Azure AD and ADFS. The WebApp is using an Azure App registration. The Reply URL which has been set there is https://mysite.com/signin-oidc
I have already added these code parts in the code:
`public void ConfigureServices(IServiceCollection services)
{
services.AddMvc();

services.Configure<ForwardedHeadersOptions>(options =>
{
    options.ForwardedHeaders = 
        ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto;
});

}

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseForwardedHeaders();

if (env.IsDevelopment())
{
    app.UseDeveloperExceptionPage();
}
else
{
    app.UseExceptionHandler("/Home/Error");
}

app.UseStaticFiles();
// In ASP.NET Core 1.x, replace the following line with: app.UseIdentity();
app.UseAuthentication();
app.UseMvc();

}`

And
app.Use((context, next) => { context.Request.Scheme = "https"; return next(); });

I have added both since the detected Redirect URI by Kestrel was http and not https while thats the only scheme I can set on Azure. I have also tried just using the XForwardProto and not with XForwardFor. That also works but the results stays the same.

The Dockerfile is :

`FROM microsoft/dotnet:2.2-sdk AS build-env

RUN mkdir /myapp
COPY ./ ./myapp
WORKDIR /my-app

RUN apt-get update -yq && apt-get upgrade -yq && apt-get install -yq curl git nano
RUN curl -sL https://deb.nodesource.com/setup_8.x | bash - && apt-get install -yq nodejs build-essential
RUN npm install -g npm && npm install -g @angular/cli@latest

WORKDIR /my-app/myapp.CoreWeb/
RUN dotnet publish -c Release -o drop

FROM microsoft/dotnet:2.2-aspnetcore-runtime-alpine
RUN adduser --disabled-password --gecos "" appuser
RUN chown -R appuser:appuser /my-app
USER appuser
EXPOSE 5000
ENV ASPNETCORE_URLS http://+:5000
COPY --from=build-env /my-app/myapp.CoreWeb/drop ./
ENTRYPOINT ["dotnet", "myapp.CoreWeb.dll"]`

The Apache Vhost settings are:

`<VirtualHost :>
RequestHeader set "X-Forwarded-Proto" expr=%{REQUEST_SCHEME}

<VirtualHost :80>
SetEnvIf SERVER_ENV ^(.)$ SERVER_ENV=stage
ServerName mysite.com
ServerAlias None
ProxyRequests off
<Proxy >
Order deny,allow
Allow from all


ProxyPreserveHost On
ProxyPass http://127.0.0.1:8081/
ProxyPassReverse http://127.0.0.1:8081/

RewriteEngine On
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteRule (.) https://%{HTTP_HOST}$1 [R,L]
SetEnvIf X-Forwarded-For "^......." forwarded
CustomLog /apacheLogLocation/mysite.com.stage.access.log vhost_verbose env=!forwarded
CustomLog /apacheLogLocation/mysite.com.stage.access.log vhost_verbose_lb env=forwarded
ErrorLog /apacheLogLocation/mysite.com.stage.error.log
`

When I check the fiddler to see if the redirect URI is correct, its https. When I check the docker logs I don't see anything suspicious and the I can also see the cookie signin which i guess means the authentication was fine(not sure!) and it also tries to open the dll and index file of the web app. Ehn I do the cURL in verbose it ends up in 302 (redirection).
I am out of ideas and have already read the following threads but no success:
https://docs.microsoft.com/en-us/aspnet/core/host-and-deploy/proxy-load-balancer?view=aspnetcore-2.2
aspnet/Security#757
aspnet/Security#1070
dotnet/AspNetCore.Docs#2384
aspnet/Security#929