Seems like Layouts CAN set HTTP response headers, contrary to the docs? #11843
Description
📚 Subject area/topic
On-demand rendering, setting response headers in layouts
📋 Page(s) affected (or suggested, for new content)
https://docs.astro.build/en/guides/on-demand-rendering/#on-demand-rendering-features
📋 Description of content that is out-of-date or incorrect
On the on-demand rendering page, there is a big warning that HTTP headers cannot be modified inside layouts, only pages:
However, as far as I can tell, this isn't true?
Starting from npm create astro@latest and using the basic template:
/src/pages/index.astro:
---
import Welcome from '../components/Welcome.astro';
import Layout from '../layouts/Layout.astro';
Astro.response.headers.append('header-sources', '/pages/index.astro')
---
<Layout>
<Welcome />
</Layout>/src/layouts/Layout.astro:
---
Astro.response.headers.append('header-sources', '/layouts/Layout.astro')
---
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width" />
<link rel="icon" type="image/svg+xml" href="/favicon.svg" />
[...snipped...]It seems like the layout DOES affect the final headers:
I'm not sure if this is a documentation error, or if there's some other way of setting headers that isn't supported, but Astro.response.headers() does work...? Or are there some edge cases in which it won't...?
🖥️ Reproduction in StackBlitz (if reporting incorrect content or code samples)
https://stackblitz.com/~/github.com/arcataroger/astro-header-modification-in-layout
Inside StackBlitz, I think you have to open the browser inspector and then reload the preview iframe:
