Inject Webpack output HTML into ASP.NET MVC

WebpackController.cs

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Net.Http;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Web.Hosting;
using System.Web.Mvc;

namespace TestWp.Controllers
{
    public class WebpackController : Controller
    {
        [ChildActionOnly]
        public ActionResult Head()
        {
            var html = GetWebpackHtml("head");
            return Content(html);
        }

        [ChildActionOnly]
        public ActionResult Body()
        {
            var html = GetWebpackHtml("body");
            return Content(html);
        }

        private string GetWebpackHtml(string tag)
        {
            var webpackDevServerUrl = ConfigurationManager.AppSettings["WebpackDevServer"];
            string html;

            if (!string.IsNullOrEmpty(webpackDevServerUrl))
            {
                html = GetHttpString($"{webpackDevServerUrl}/index.html");
            }
            else
            {
                html = System.IO.File.ReadAllText(HostingEnvironment.MapPath("~/static/index.html"));
            }
            
            var match = Regex.Match(html, $"<{tag}>(.*)</{tag}>", RegexOptions.Singleline);
            var innerHtml = match.Groups[1].Value;

            return innerHtml;
        }

        private string GetHttpString(string url)
        {
            var http = new HttpClient();

            try
            {
                return Task.Run(async () => await http.GetStringAsync(url)).GetAwaiter().GetResult();
            }
            catch (HttpRequestException ex)
            {
                var error = (Exception) ex;

                while (error.InnerException != null)
                {
                    error = error.InnerException;
                }

                throw new InvalidOperationException("Webpack dev server is not started. Run `yarn serve` in ClientApp directory. Error: " + error.Message);
            }
        }
    }
}