Program.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace SafeAccountsUI {
    public class Program {
        public static void Main(string[] args)
        {
            SetEnvVariables();
            CreateHostBuilder(args).Build().Run();
        }

        private static void SetEnvVariables()
        {
            if (!File.Exists(".env"))
                throw new Exception("No .env file present");

            foreach (var line in File.ReadAllLines(".env")) {
                var parts = line.Split(
                    '=',
                    StringSplitOptions.RemoveEmptyEntries);

                if (parts.Length != 2)
                    continue;

                Environment.SetEnvironmentVariable(parts[0], parts[1]);
            }
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });
    }
}