@astrojs/vercel - AdapterSupportOutputMismatch

[phenomen]

Astro Info

Astro                    v5.0.0-beta.6
Node                     v18.20.3
System                   Linux (x64)
Package Manager          npm
Output                   static
Adapter                  @astrojs/vercel
Integrations             none

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

No response

Describe the Bug

After upgrading to "astro": "5.0.0-beta.6" and "@astrojs/vercel": "8.0.0-beta.3" I get an error:

[AdapterSupportOutputMismatch] The `@astrojs/vercel` adapter is configured to output a static website, but the project contains server-rendered pages. Please install and configure the appropriate server adapter for your final deployment.
  Error reference:
    https://docs.astro.build/en/reference/errors/adapter-support-output-mismatch/
  Stack trace:
    at new AstroError (file:///home/projects/withastro-astro-fewhsc/node_modules/astro/dist/core/errors/errors.js:37:5)
    at setAdapter (file:///home/projects/withastro-astro-fewhsc/node_modules/astro/dist/integrations/hooks.js:265:45)
    at Module.runHookConfigDone (file:///home/projects/withastro-astro-fewhsc/node_modules/astro/dist/integrations/hooks.js:262:59)
    at async AstroBuilder.run (file:///home/projects/withastro-astro-fewhsc/node_modules/astro/dist/core/build/index.js:196:23)
    at async build (file:///home/projects/withastro-astro-fewhsc/node_modules/astro/dist/cli/build/index.js:44:3)
 ELIFECYCLE  Command failed with exit code 1.

From what I understand, static is a correct output if just a few pages/endpoints have export const prerender = false;

In the linked reproduction, run npm run build to repro the error.

What's the expected result?

Successful build.

Link to Minimal Reproducible Example

https://stackblitz.com/edit/withastro-astro-fewhsc?file=package.json

Participation

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

[bluwy]

Looks like we need to update the vercel adapter code here to use the value of buildOutput from the astro:config:done hook instead of from the astro:config:setup hook:

adapters/packages/vercel/src/index.ts

Lines 277 to 289 in aed689d

	'astro:config:done': ({ setAdapter, config }) => {
	if (buildOutput === 'server') {
	setAdapter(getAdapter({ buildOutput, edgeMiddleware, middlewareSecret, skewProtection }));
	} else {
	setAdapter(
	getAdapter({
	edgeMiddleware: false,
	middlewareSecret: '',
	skewProtection,
	buildOutput,
	})
	);
	}

. That way setAdapter uses the right value that doesn't trigger the error.

That solves this issue, however it also looks like vercel is using the buildOutput during astro:config:setup, which is a little problematic because that's not the final value yet.

adapters/packages/vercel/src/index.ts

Lines 196 to 207 in aed689d

	'astro:config:setup': async ({ command, config, updateConfig, injectScript, logger }) => {
	buildOutput = config.output;
	if (webAnalytics?.enabled) {
	injectScript(
	'head-inline',
	await getInjectableWebAnalyticsContent({
	mode: command === 'dev' ? 'development' : 'production',
	})
	);
	}
	if (buildOutput === 'server') {

Unless there's a way to share the same config in agnostic of server or static, @ematipico I think making @astrojs/adapter as a single entrypoint might not work here. Perhaps you have some ideas to fix this.

[ematipico]

which is a little problematic because that's not the final value yet.

Is there a case where buildOutput starts as server but then the final value is static?

[bluwy]

It should only ever go from static to server based on this code: https://github.com/withastro/astro/blob/731b69712b0e9c5d5a4058db3fa3e8bf628c7aad/packages/astro/src/core/routing/manifest/prerender.ts#L28

I've discussed with Erika before if we could detect the case where the user set server but every route is set to prerender true, in which it should ended up as static, but we didn't implement it as it doesn't make sense to do so in practice.

[princemuel]

I'm also experiencing this problem

[samparmenter]

Having the same issue here. Output set to static as almost the entire site is static bar a couple of /api routes but using the @astro/vercel adaptor I am seeing The @astrojs/vercel adapter is configured to output a static website, but the project contains server-rendered pages. Please install and configure the appropriate server adapter for your final deployment.

In the single api route I currently have I have export default prerender = false;

Using the @astro/node adapter it all works as expected locally and respects the idea that all pages are static unless the 'opt out' of prerendering has been set.