Is my Function being requested too often (recursing?)

Developers Cloudflare Pages
1

Hello community,

I’m using a Pages Function to create a Content-Security Policy with nonces for inline scripts. Things are working as expected, but each time I invoke the Function, it adds 7-8 to my Functions count for the day. I wonder if I’m invoking it too often or there’s a recursion happening I don’t need.

// Additional code for HTMLRewriter and nonce generator omitted for brevity

export const onRequest = async ({ request, next, env }) => {
  const response = await next();

  if (response.status === 304) {
    return response;
  } else {
    response.headers.set(
      "Content-Security-Policy",
      "default-src 'self'; ... et al"
    );
    response.headers.set("cf-nonce-generator", "HIT");

    // Find the nonce string and replace it
    const rewriter = new HTMLRewriter()
      .on("script", new AttributeWriter("nonce", oldValue, newValue))
      .transform(response);

    return rewriter;
  }
};

My only thought is to switch onRequestGet to onRequest because this Function should only be invoked on GET requests. Other than that I have no good ideas and haven’t found any documentation to optimize number of invocations.

2

Where are you running this Function? Is it on every single request such as via _middleware.js? If so, this’ll also fire for every asset on your site too.

So for example, if I load your website that requests 2 images, 2 JS files, 2 CSS files, and the HTML file, that’s going to be 7 effective invocations for each page load.

1 Like
3

I wondered if that might be the case. I’m running it as index.js right now, but there are 7 or 8 GET requests for that page.

Is there a way to only invoke the Function on the initial request, or are those extra runs the tradeoff of using Functions to add my CSP headers?

4

You might be able to prevent the Function from running on specific requests by using a _routes.json.

1 Like
5

I follow you. By adding the directories I want ignored to the exclude array in _routes.json, I might be able to reduce the number of Function invocations.

6

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