feature(astrojs/cloudflare): add support for splitted SSR bundles

[alexanderniebuhr]

Changes

DEMO: https://astro-ssr-split-directory.pages.dev

• adds support for build.split in astrojs/cloudflare
• does not work with prerenderd pages yet (however that seems to be a bug in build.split itself SSR split seems to not output prerendered html pages #7466) @ematipico can you help?
• is not yet tested with dynamic rest routes [...props].astro
• closes SSR split does not work with Cloudflare #7462
• related to: feat: SSR split mode #7220
• related to: feat: document the new split option docs#3504
• depends on: fix: correct URL for entry points #7490

Tasks

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1. make it work with prerendering
2. check dynamic rest parameters
3. improve fileURL remapping (maybe unnecessary with new hooks in future)
4. replace functions mode with check if directory + split is set
5. combine code to get rid of temporaray if branches.
6. improve filename replacement
7. add support for middleware
8. evaluate poiting eslint to the functions folder directly & use regex for renaming

Testing

• added test suite & manually with cloudflare pages demo

Docs

/cc @withastro/maintainers-docs for feedback!

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[alexanderniebuhr]

@ematipico first of all, sorry for pinging. But I would like to get this one out as soon as possible; I think having experimental support is in any way better than having no support! Iteration in the future can improve the support.

Not sure if you are the correct one to review, but if you can help with getting this on track would be amazing.

[matthewp]

This looks great! Left a couple of comments on the code, but overall like the implementation.

Just so I understand, this is not toggling split on at the integration, but rather respecting the user's split value, right?

[alexanderniebuhr]

Just so I understand, this is not toggling split on at the integration, but rather respecting the user's split value, right?

Yes this is totally right. It just makes current cloudflare adapter work with the following user options (while before it was just breaking):

adapter: cloudflare({ mode: 'directory' }),
build: {
    split: true,
    excludeMiddleware: true
},

[matthewp]

Hey @alexanderniebuhr This is looking great! Have been talking about the astro:build:ssr having incorrect paths with @ematipico and we think we need to fix that issue first so that adapters don't need to deal with it.

Leaving a note here on that issue just because I don't think there's a better place. @ematipico in my investigation what I see is:

1. In astro:build:ssr these paths are wrong but the real files do exist inside of build.server.
   • This makes me think that it's a matter of the wrong paths being saved in internals.
2. Also of note, the real files are hashed filenames that are later renamed to the "pretty names" here:

   astro/packages/astro/src/core/build/static-build.ts

   Lines 299 to 301 in 0daaa9e

   	const fileURL = new URL(fileName, root);
   	await fs.promises.mkdir(new URL('./', fileURL), { recursive: true });
   	await fs.promises.writeFile(fileURL, mutation.code, 'utf-8');

   • Should they be renamed to the pretty names or should they rename the hash names?
   • If we need/want the prettier names, then we need to make it so that the astro:build:ssr hook runs after this code. Currently it does not.

[ematipico]

!preview cloudflare-split

[ematipico]

The first round of code review. It looks good to me, nothing major from my point of view, and the tests seem solid.

Let's wait for the docs team

[ematipico]

By the way, @alexanderniebuhr , this contribution of yours is fantastic! Great work, and thank you! 🚀

[sarah11918]

Thanks for this helpful contribution, @alexanderniebuhr! I'm sure people are going to appreciate this!

Left some suggestions for your consideration based on:

• Is this actually "experimental" (i.e. behind a flag?) vs just "new"?
• Changesets are now being used to autogenerate blog post material, so congrats, this PR is suffering through those growing pains of changeset editing, not just README editing! 😄
• suggestion to maybe not refer to the optional config so early on, front-loading an already kind of big/explainy paragraph of the default behavior, and letting the 2nd paragraph do the heavy lifting?

[sarah11918]

Docs is happy! 🥳