Startup.cs

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

public IConfiguration Configuration { get; }

// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    app.Use(async (context, next) =>
    {
        // Do work that doesn't write to the Response.
        await next.Invoke();
        // Do logging or other work that doesn't write to the Response.
    });
}