feat: generate the Cloudflare Workers deployment output with the Vite plugin by teemingc · Pull Request #17520 · sveltejs/kit

teemingc · 2026-10-22T07:58:55Z

This PR uses the Cloudflare Vite plugin to create a suitable deployment artefact for Cloudflare Workers. Therefore, we get all the goodies such as:

a generated Wrangler deployment config for unbundled deployments by default
a full build artefact without relying on Wrangler's bundling

… plugin

pkg-svelte-dev · 2026-10-22T07:58:58Z

Install the latest version of @sveltejs/kit from d218d58:

pnpm add https://pkg.svelte.dev/@sveltejs/kit/c/d218d583b3d7483b33ed22b8615eacaedf010341

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/kit/pr/17520

changeset-bot · 2026-10-22T07:58:59Z

🦋 Changeset detected

Latest commit: d218d58

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@sveltejs/adapter-cloudflare	Major

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

svelte-docs-bot · 2026-10-22T08:00:51Z

Preview: https://svelte-dev-git-preview-kit-17520-svelte.vercel.app/

…' into claude/cloudflare-workers-build-output # Conflicts: # documentation/docs/25-build-and-deploy/60-adapter-cloudflare.md # packages/adapter-cloudflare/index.spec.js

teemingc · 2026-10-26T14:06:43Z

-	// we need the `assets.directory` key so that the static assets are deployed
-	if ((wrangler_config.main || wrangler_config.assets) && !wrangler_config.assets?.directory) {
-		throw new Error(
-			`You must specify the \`assets.directory\` key in ${config_path}. Consult https://developers.cloudflare.com/workers/static-assets/binding/#directory`
-		);
-	}
-
-	// we need the `assets.binding` key so that the Worker can access the static assets
-	if (wrangler_config.main && !wrangler_config.assets?.binding) {
-		throw new Error(
-			`You must specify the \`assets.binding\` key in ${config_path} before deploying your Worker. Consult https://developers.cloudflare.com/workers/static-assets/binding/#binding`
-		);
-	}
-
-	// the user might have forgot the `main` key or should remove the `assets.binding`
-	// key to deploy static assets without a Worker
-	if (!wrangler_config.main && wrangler_config.assets?.binding) {
-		throw new Error(
-			`You must specify the \`main\` key in ${config_path} if you want to deploy a Worker alongside your static assets. Otherwise, remove the \`assets.binding\` key if you only want to deploy static assets.`
-		);
-	}


adapter generates overrides for these so the user never needs to specify them anymore

teemingc · 2026-10-27T13:18:24Z

 		"dev": "vite dev",
 		"build": "vite build",
-		"preview": "wrangler dev dist/index.js --config config/wrangler.jsonc",
+		"preview": "wrangler dev",


we generate a deployment config that wrangler automatically picks up, so users don't need to specify the build output path or user wrangler config path anymore

teemingc · 2026-10-27T13:58:46Z

-	// a Vite root that differs from the working directory
-	const root = fs.mkdtempSync(path.join(os.tmpdir(), 'adapter-cloudflare-'));
-
+test('selects Wrangler configuration and named environments from Vite env files', async () => {


tests that https://developers.cloudflare.com/workers/vite-plugin/reference/cloudflare-environments/ works

…adapter config path now resolves for the Cloudflare build plugins but fails in the development platform proxy, preventing the dev server from starting. This commit fixes the issue reported at packages/adapter-cloudflare/config.js:36 This change makes `options.config` relative to Vite's root, but `virtual_workers_module` still passes that same relative string directly to Wrangler's `getPlatformProxy` and `unstable_readConfig`, which resolve it against the working directory. Reproduced from the adapter directory with Vite root `test/apps/workers` and adapter config `config/wrangler.jsonc`: configuration resolves, but dev-server setup fails with `Could not read file: config/wrangler.jsonc`. The suggested patch resolves the proxy's config path against the resolved Vite root before setup and watching. With the patch, the same dev server starts and its platform binding matches the selected Wrangler config. Adapter type checks passed. Co-authored-by: Vercel <vercel[bot]@users.noreply.github.com> Co-authored-by: teemingc <chewteeming01@gmail.com>

…ev` loses them because the generated `.dev.vars` stays inside `worker/server` while the deployment config moves to `worker`. This commit fixes the issue reported at packages/adapter-cloudflare/index.js:53-55 Cloudflare's output-config plugin emits a `.dev.vars` alongside the original server build. `writeServer` copies it into `worker/server`, but the adapter puts the final `wrangler.json` one directory above it. Wrangler loads local secrets relative to the selected config's directory, so the new `wrangler dev` preview workflow no longer sees these bindings (or uses the deployed `vars` value instead of the local override). Reproduced by building the Workers app with a local `FOO` override: Wrangler's installed `unstable_getVarsForDev` returns that override for the source config but no bindings for the final deployment config. Moving the emitted file alongside the final config restores the override. Rebuilt the app and verified the binding using the same Wrangler API; adapter type checks passed. Co-authored-by: Vercel <vercel[bot]@users.noreply.github.com> Co-authored-by: teemingc <chewteeming01@gmail.com>

…e forwarded Cloudflare `configResolved` hook runs while the plugins that initialize its context are disabled for preview. This commit fixes the issue reported at packages/adapter-cloudflare/config.js:115-130 Reproduced with the Workers test app: `vite preview` exits with `AssertionError: Expected resolvedPluginConfig to be defined` before starting the server. The new wrapper has no `apply` guard, unlike the initialization and environment plugins, so its forwarded hook accesses an uninitialized Cloudflare context. The suggested patch gives this wrapper the same dev/build guard. Validated by resolving Vite configuration with `isPreview: true`, which succeeds with the patch. Adapter unit tests and type checks also passed before this change. Co-authored-by: Vercel <vercel[bot]@users.noreply.github.com> Co-authored-by: teemingc <chewteeming01@gmail.com>

ottomated · 2026-10-28T02:26:46Z

@@ -0,0 +1 @@
+export const variables = { FOO: {} };


Same issue as last PR with FOO here. Currently we don't pick up variables defined in wrangler.jsonc, and I don't think we should.

Mm should we not? I think I overlooked this. There's an existing issue about this where it's a hassle to manually sync the vars in wrangler.jsonc and in .env. Maybe we should load them during dev, build, and preview? From the wrangler file property description it says: "A map of environment variables to set when deploying your Worker." so it seems like they're expected to be present wherever.

Hmm I guess we should if there are issues open about it. We can probably do that pretty easily as a vite plugin, right? I don't know how hard it is to augment vite's env variables.

feat: generate the Cloudflare Workers deployment output with the Vite…

484d97e

… plugin

teemingc added pkg:adapter-cloudflare needs-platform-tests This PR needs to run platform tests in order to merge. breaking change and removed breaking change labels Oct 22, 2026

teemingc added 14 commits October 23, 2026 14:59

Merge remote-tracking branch 'origin/teemingc-remove-cloudflare-pages…

9a3df63

…' into claude/cloudflare-workers-build-output # Conflicts: # documentation/docs/25-build-and-deploy/60-adapter-cloudflare.md # packages/adapter-cloudflare/index.spec.js

chore: remove unused imports

aa3d1b7

Update better-houses-vanish.md

2caef8e

Update 60-adapter-cloudflare.md

e47abb1

Update 60-adapter-cloudflare.md

c562393

Update 60-adapter-cloudflare.md

b48c3ec

Update index.d.ts

21354bf

clean up build test

c1db22a

Update package.json

b69e29e

Update package.json

2a6d837

Update vite.config.js

0b1ed17

Update index.js

08bd2ff

Update vite.config.js

625950e

override main and assets

97d047d

teemingc commented Oct 26, 2026

View reviewed changes

teemingc added 7 commits October 27, 2026 00:14

Update config.js

f9f875a

clean up

ae87b78

fix

28f0e00

Update config.js

b40c346

Update config.js

b6a6654

Update config.js

f67763b

clean up

d798472

Update package.json

f4992b3

teemingc commented Oct 27, 2026

View reviewed changes

teemingc added 4 commits October 27, 2026 23:24

Update package.json

9eca2f3

Update config.spec.js

0be70df

fix

e806240

fix

cdf98a4

teemingc commented Oct 27, 2026

View reviewed changes

teemingc added 2 commits October 28, 2026 00:03

clean up

af96682

revert

9225d3e

teemingc marked this pull request as ready for review October 27, 2026 14:07

This was linked to issues Oct 27, 2026

adapter-cloudflare seems to undo all code splitting, and worse #2963

Open

adapter-cloudflare@5.0.0 breaks deployment #13300

Open

vercel Bot reviewed Oct 27, 2026

View reviewed changes

Comment thread packages/adapter-cloudflare/config.js

Comment thread packages/adapter-cloudflare/index.js

Comment thread packages/adapter-cloudflare/config.js

vercel Bot and others added 4 commits October 27, 2026 14:39

only calculate padding once

652a2a0

ottomated approved these changes Oct 28, 2026

View reviewed changes

ottomated requested changes Oct 28, 2026

View reviewed changes

Comment thread packages/adapter-cloudflare/test/apps/workers/package.json

Update wrangler.jsonc

d218d58

Navigation Menu

Repository navigation

feat: generate the Cloudflare Workers deployment output with the Vite plugin - #17520

feat: generate the Cloudflare Workers deployment output with the Vite plugin#17520
teemingc wants to merge 34 commits into
teemingc-remove-cloudflare-pagesfrom
claude/cloudflare-workers-build-output

teemingc commented Oct 22, 2026 •

edited

Loading

Uh oh!

pkg-svelte-dev Bot commented Oct 22, 2026 •

edited

Loading

Uh oh!

changeset-bot Bot commented Oct 22, 2026 •

edited

Loading

Uh oh!

svelte-docs-bot Bot commented Oct 22, 2026

Uh oh!

teemingc Oct 26, 2026 •

edited

Loading

Uh oh!

teemingc Oct 27, 2026

Uh oh!

teemingc Oct 27, 2026

Uh oh!

Uh oh!

Uh oh!

Uh oh!

ottomated Oct 28, 2026

Uh oh!

teemingc Oct 28, 2026 •

edited

Loading

Uh oh!

ottomated Oct 28, 2026

Uh oh!

Uh oh!

This branch has not been deployed

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Conversation

teemingc commented Oct 22, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

pkg-svelte-dev Bot commented Oct 22, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

changeset-bot Bot commented Oct 22, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

🦋 Changeset detected

Uh oh!

svelte-docs-bot Bot commented Oct 22, 2026

Uh oh!

teemingc Oct 26, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

teemingc Oct 27, 2026

Choose a reason for hiding this comment

Uh oh!

teemingc Oct 27, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

ottomated Oct 28, 2026

Choose a reason for hiding this comment

Uh oh!

teemingc Oct 28, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

ottomated Oct 28, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

This branch has not been deployed

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

teemingc commented Oct 22, 2026 •

edited

Loading

pkg-svelte-dev Bot commented Oct 22, 2026 •

edited

Loading

changeset-bot Bot commented Oct 22, 2026 •

edited

Loading

teemingc Oct 26, 2026 •

edited

Loading

teemingc Oct 28, 2026 •

edited

Loading