Startup.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Webdictaat.Apis.Databases.Model;
using MySQL.Data.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;

namespace Webdictaat.Apis.Databases
{
    public class Startup
    {
        public IConfiguration Configuration { get; }

        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        // This method gets called by the runtime. Use this method to add services to the container.
        // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddDbContext<MyDbContext>(options =>
            {
                options.UseMySQL(Configuration.GetConnectionString("DatabaasConnection"));
            });

            services.AddSingleton<ISecretService>(new SecretService(Configuration["secret"]));


            services.AddCors();
            services.AddMvc(options => options.EnableEndpointRouting = false);
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseCors(b => b
               .AllowAnyOrigin()
               .AllowAnyHeader()
               .AllowAnyMethod());

            app.UseMvc();
        }
    }
}