fix: --experimental-ssr fixes

[JuanM04]

Changes

Replaced --experimental-ssr with the internal function isBuildingToSSR, which reads the brand-new adapter inside the Astro config.

• Use isBuildingToSSR() everywhere.
• --experimental-ssr flag now is required when using 3rd-party adapters.

This change has a side effect: it now respects the output given by the integrations through buildConfig and (somehow) doesn't copy the contents of public/ into the dist folder. @matthewp maybe you can help me with this?

Testing

TBD

Docs

TBD

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[matthewp]

Hm, so you're saying that public/ works before this change with the flag but fails just by using this internal code instead? I'm not sure why that would be, you might need to debug it more. I believe Vite is the one doing the copying there, with the publicDir config, maybe that is being messed up some how?

[JuanM04]

Things were broken in a different way before - for example, now buildConfig is respected.

Nonetheless, this new test also fails in the main branch.

[matthewp]

Oh, I just read the test. You are expecting to get the public/ file by calling the adapter, but that test adapter doesn't implement static file serving. That would be a feature of the adapter, not a feature of our SSR implementation.

[JuanM04]

That would be a feature of the adapter, not a feature of our SSR implementation.

If you clone this PR and run the following:

pnpm install
pnpm build
cd examples/blog
pnpm astro add node --yes
pnpm build

You'll see the contents of the public folder inside dist/client. Nonetheless, if you run the same steps inside examples/minimal, dist/client/ is empty. That's what I'm referring to

You are expecting to get the public/ file by calling the adapter, but that test adapter doesn't implement static file serving.

Ohhh, I see. I removed that test, but the problem described above persists

[matthewp]

Yeah, perhaps something about minimal is causing a bug then? I'm not sure.

Talked about this overall idea with the team and we want to make it so that the flag is still required if using a 3rd-party adapter, but not needed if using a built-in adapter.

This mimics how integrations work, where the flag is needed if using a 3rd party one.

[JuanM04]

we want to make it so that the flag is still required if using a 3rd-party adapter

Perfect, I could add that to isBuildingToSSR!

Yeah, perhaps something about minimal is causing a bug then? I'm not sure.

After some searching, I think the issue is here. When there is no JavaScript to be generated, the build process is omitted. This leads to sites with static assets (and probably some CSS) to not have its assets copied if there is no JS.

[matthewp]

After some searching, I think the issue is here. When there is no JavaScript to be generated, the build process is omitted. This leads to sites with static assets (and probably some CSS) to not have its assets copied if there is no JS.

Ah, yeah that does make sense. I think I can fix that in another PR.

[matthewp]

Here's how the integrations flag is implemented: 9d6e0b5

[matthewp]

Code looks good, maybe need to rebase with main to clear up the failing test?

[matthewp]

Great, thank you!