Docker image: Unable to configure HTTPS endpoint. No server certificate was specified, and the default developer certificate could not be found

I am trying to run an ASP.NET Core 3.1 framework based app on an Ubuntu (18.04.3 LTS) server using Docker container.

I created the following docker-compose.yml file to be able to run both nginx-proxy and private_image_name images on my server. Obviously, nginx-proxy is a proxy server that will be the proxy that would route traffic coming from the web to my other running images. I followed the article for the nginx-proxy setup.

version: '3.4'
services:

  nginx-proxy:
    image: jwilder/nginx-proxy
    container_name: nginx-proxy
    ports:
      - 80:80
      - 443:443
    volumes:
      - /var/run/docker.sock:/tmp/docker.sock:ro
      - certificates:/etc/certificates

  private_image_name:
    image: private_image_name:latest
    container_name: private_image_name
    depends_on:
      - nginx-proxy
    environment:
      - VIRTUAL_HOST=sub.domain-example.com
      - ASPNETCORE_ENVIRONMENT=Production
      - ASPNETCORE_URLS=https://+:443;http://+:80
    ports:
      - 51736:80
      - 44344:443
    volumes:
      - storage:/storage
      - /var/run/docker.sock:/tmp/docker.sock:ro
      - certificates:/etc/certificates
      - ${APPDATA}/Microsoft/UserSecrets:/root/.microsoft/usersecrets:ro
      - ${APPDATA}/ASP.NET/Https:/root/.aspnet/https:ro
volumes:
  storage:
  certificates:
networks:
  default:
    external:
      name: nginx-proxy
secrets:
  server.cert:
    file: ./server.cert
  server.key:
    file: ./server.key

Both server.cert and server.key files are stored in /etc/certificates. Both files were created using the following command

sudo openssl req -new -newkey rsa:4096 -days 3650 -nodes -x509 -subj "/C=US/ST=CA/L=SF/O=Docker-demo/CN=app.example.org" -keyout server.key -out server.cert

I attempted to run both of my images by executing docker-composer up. However, the nginx-proxy came up with no issue and while private_image_name failed to run. The following is what I get when running the private_image_name attempts to start

**WARNING**: The APPDATA variable is not set. Defaulting to a blank string.
Recreating private_image ... done
Attaching to private_image
private_image    | crit: Microsoft.AspNetCore.Server.Kestrel[0]
private_image    |       Unable to start Kestrel.
private_image    | System.InvalidOperationException: Unable to configure HTTPS endpoint. No server certificate was specified, and the default developer certificate could not be found or is out of date.
private_image    | To generate a developer certificate run 'dotnet dev-certs https'. To trust the certificate (Windows and macOS only) run 'dotnet dev-certs https --trust'.
private_image    | For more information on configuring HTTPS see https://go.microsoft.com/fwlink/?linkid=848054.
private_image    |    at Microsoft.AspNetCore.Hosting.ListenOptionsHttpsExtensions.UseHttps(ListenOptions listenOptions, Action`1 configureOptions)
private_image    |    at Microsoft.AspNetCore.Hosting.ListenOptionsHttpsExtensions.UseHttps(ListenOptions listenOptions)
private_image    |    at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.AddressesStrategy.BindAsync(AddressBindContext context)
private_image    |    at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.BindAsync(IServerAddressesFeature addresses, KestrelServerOptions serverOptions, ILogger logger, Func`2 createBinding)
private_image    |    at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServer.StartAsync[TContext](IHttpApplication`1 application, CancellationToken cancellationToken)
private_image    | Unhandled exception. System.InvalidOperationException: Unable to configure HTTPS endpoint. No server certificate was specified, and the default developer certificate could not be found or is out of date.
private_image    | To generate a developer certificate run 'dotnet dev-certs https'. To trust the certificate (Windows and macOS only) run 'dotnet dev-certs https --trust'.
private_image    | For more information on configuring HTTPS see https://go.microsoft.com/fwlink/?linkid=848054.
private_image    |    at Microsoft.AspNetCore.Hosting.ListenOptionsHttpsExtensions.UseHttps(ListenOptions listenOptions, Action`1 configureOptions)
private_image    |    at Microsoft.AspNetCore.Hosting.ListenOptionsHttpsExtensions.UseHttps(ListenOptions listenOptions)
private_image    |    at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.AddressesStrategy.BindAsync(AddressBindContext context)
private_image    |    at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.AddressBinder.BindAsync(IServerAddressesFeature addresses, KestrelServerOptions serverOptions, ILogger logger, Func`2 createBinding)
private_image    |    at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServer.StartAsync[TContext](IHttpApplication`1 application, CancellationToken cancellationToken)
private_image    |    at Microsoft.AspNetCore.Hosting.GenericWebHostService.StartAsync(CancellationToken cancellationToken)
private_image    |    at Microsoft.Extensions.Hosting.Internal.Host.StartAsync(CancellationToken cancellationToken)
private_image    |    at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.RunAsync(IHost host, CancellationToken token)
private_image    |    at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.RunAsync(IHost host, CancellationToken token)
private_image    |    at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.Run(IHost host)
private_image    |    at private_image.Program.Main(String[] args) in /src/private_image/Program.cs:line 17
private_image exited with code 139

The command dotnet dev-certs https --trust works on Windows and macOS only.

Question

How can I fix this issue on the Ubuntu server? How can I correctly attach the SSL cert to the docker image?

Additionally, when I go to http://server-ip-address or http://sub.domain-example.com I get

503 Service Temporarily Unavailable nginx/1.17.5

And when I go to https://server-ip-address or https://sub.domain-example.com I get

Unable to connect.