A snippet that shows two ways to read files using ASP.NET 5

Startup.cs

// Using File.ReadAllText

public async Task MyMiddleWare(HttpContext context, IApplicationEnvironment env)
{
    var html = File.ReadAllText(env.ApplicationBasePath + "/Views/index.html");
    await context.Response.WriteAsync(html); 
}

// Using FileProvider

public void ConfigureServices(IServiceCollection services)
{
    services.AddTransient<IFileProvider>(s=>new PhysicalFileProvider(s.GetRequiredService<IApplicationEnvironment>().ApplicationBasePath));
}

public async Task MyMiddleWare(HttpContext context, IFileProvider fileProvider)
{
    var html = ReadAllFromStream(fileProvider.GetFileInfo("Views/index.html").CreateReadStream());
    await context.Response.WriteAsync(html); 
}

private string ReadAllFromStream(Stream stream)
{
    using (var reader = new StreamReader(stream))
    {
        return reader.ReadToEnd();
    }
}