Blazor streaming rendering responses should expose a custom header indicating that streaming takes place

[oliverw]

Is there an existing issue for this?

• I have searched the existing issues

Is your feature request related to a problem? Please describe the problem.

It would be helpful if Blazor could add a custom header to the response, if streaming rendering is in effect to tell downstream proxies which adaptively buffer responses to not buffer in this case.

One example is Cloudflare's Argo Tunnel which disables buffering based on the Content-Type header as shown here. Even though a custom header would not fix the problem, it would open the door to a PR.

Describe the solution you'd like

Have blazor expose a custom header for streaming rendering responses.

Additional context

No response

[javiercn]

@oliverw thanks for contacting us.

For streaming rendering to work, nothing in the connection can buffer the contents. You can set a custom header today on the response and see if you are able to bypass the buffering that way.

[javiercn]

A custom header can be added as follows:

app.MapRazorComponents<App>()
    .Add(endpointBuilder => 
        endpointBuilder.RequestDelegate = async context =>
        {
            // Set your custom header
            context.Response.Headers["X-My-Header"] = "BlazorRocks";

            // Call the original Blazor endpoint
            await originalDelegate(context);
        });

We don't believe we need to add a custom response header nor change our content type, the proxy should allow configuration for this type of buffering.