StaticFileOptions.OnPrepareResponse does not get called for index.html

Question

I'm currently trying to disable the caching for index.html for my Angular SPA with a .NET Core 2.2 backend.

I'm doing this according to this answer by setting an OnPrepareResponse action for my StaticFileOptions.

But the Cache-Control header never gets sent. When I set a breakpoint in the OnPrepareResponse action I break for everyfile except index.html

What am I missing here? How can I actually control the cache for the index.html file?

// I've changed nothing else in the default ASP.NET Core/Angular template
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    // ...

    var staticFileOptions = new StaticFileOptions
    {
        OnPrepareResponse = context =>
        {
            // Breakpoint for next line hits for following files
            // 1: styles.61d14a95058dbe9da495.css
            // 2: runtime.a66f828dca56eeb90e02.js
            // 3: polyfills.7a0e6866a34e280f49e7.js
            // 4: main.d9791b5a6df420d81994.js
            // 5: favicon.ico
            if (context.File.Name == "index.html")
            {
                context.Context.Response.Headers
                    .Add("Cache-Control", "no-cache, no-store, must-revalidate");
                context.Context.Response.Headers.Add("Pragma", "no-cache");
                context.Context.Response.Headers.Add("Expires", "0");
            }
        }
    };

    app.UseStaticFiles(staticFileOptions);
    app.UseSpaStaticFiles(staticFileOptions);

    // ...
}

Answer 1

You can use this code to see if it work for you

      app.UseSpaStaticFiles(new StaticFileOptions()
            {
                OnPrepareResponse = ctx =>
                {
                    var headers = ctx.Context.Response.GetTypedHeaders();
                    headers.CacheControl = new CacheControlHeaderValue
                    {
                        Public = true,
                        MaxAge = TimeSpan.FromDays(0)
                    };

                }
            });


     app.UseSpa(spa =>
            {
                spa.Options.SourcePath = "ClientApp";
                spa.Options.DefaultPageStaticFileOptions = new StaticFileOptions()
                {
                    OnPrepareResponse = ctx => {
                        var headers = ctx.Context.Response.GetTypedHeaders();
                        headers.CacheControl = new CacheControlHeaderValue
                        {
                            Public = true,
                            MaxAge = TimeSpan.FromDays(0)
                        };
                    }
                };

                if (env.IsDevelopment())
                {
                    spa.UseAngularCliServer(npmScript: "start");
                }
            });

Answer 2

Another solution I came up with looks like this. I'm not sure I love this solution but at least it works.

app.Use(async (context, next) =>
{
    context.Response.OnStarting(() =>
    {
        var requestPath = context.Request.Path.Value;

        if (requestPath.EndsWith("index.html"))
        {
            context.Response.Headers.Add("Cache-Control", "no-cache, no-store, must-revalidate");
            context.Response.Headers.Add("Pragma", "no-cache");
            context.Response.Headers.Add("Expires", "0");
        }

        return Task.FromResult(0);
    });

    await next();
});