Node adapter ignores server.headers under astro preview

[nvzqz]

Astro Info

Astro                    v4.4.0
Node                     v21.5.0
System                   macOS (arm64)
Package Manager          pnpm
Output                   server
Adapter                  @astrojs/node
Integrations             none

If this issue only occurs in one browser, which browser is a problem?

No response

Describe the Bug

When running astro dev, the headers set by astro.config.ts are received in responses. However, they are not received when running astro preview.

The headers I'm trying to use are:

{
  "Cross-Origin-Opener-Policy": "same-origin",
  "Cross-Origin-Embedder-Policy": "require-corp",
}

What's the expected result?

Receive configured headers when running astro preview.

Link to Minimal Reproducible Example

https://github.com/nvzqz/astro-missing-headers

Participation

• I am willing to submit a pull request for this issue.

[log101]

#5564 Add headers to Vite preview server, but in SSR mode Node integration uses the server defined in createServer as far as I understood. Could we also pass the headers to this server? I can work on this if my understanding is correct.

[bluwy]

Yeah I think it also has to accept headers there. Likely we need to expand this first though:

astro/packages/astro/src/@types/astro.ts

Lines 2743 to 2751 in 9b78c99

	export interface PreviewServerParams {
	outDir: URL;
	client: URL;
	serverEntrypoint: URL;
	host: string | undefined;
	port: number;
	base: string;
	logger: AstroIntegrationLogger;
	}

So that we can get the headers from:

astro/packages/integrations/node/src/preview.ts

Line 11 in 9b78c99

const createPreviewServer: CreatePreviewServer = async function (preview) {

[log101]

Alright I'll be working on that, if you don't mind.

[log101]

In order to add headers to the response, I added a 'request' listener to the preview server and modified the response inside. It worked but now the headers are added even at 404 responses. I added a response status code check to avoid it but 404 responses still goes through.

https://github.com/log101/astro/blob/f5c2dd7686ba0a0fed64b48407a2f56793eff90f/packages/integrations/node/src/preview.ts#L39-L50

This listener is added after server is created so my listener should be called last and catch the 404 reponses but it is not. What I'm missing here?

[log101]

I couldn't solve the 404 problem, if user added custom headers at server.headers config they are present at all responses including 404. I'm not sure how could this problem be solved as 404 responses seems to be handled at the main app, which merges the responses. Also is this comment is relevant to the context?:

astro/packages/astro/src/core/app/index.ts

Lines 450 to 458 in 7fe2515

	// If you're looking at here for possible bugs, it means that it's not a bug.
	// With the middleware, users can meddle with headers, and we should pass to the 404/500.
	// If users see something weird, it's because they are setting some headers they should not.
	//
	// Although, we don't want it to replace the content-type, because the error page must return `text/html`
	headers: new Headers([
	...Array.from(newResponse.headers),
	...Array.from(originalResponse.headers),
	]),