[wrangler] Improve asset upload performance with single-file uploads by jbwcloudflare · Pull Request #14305 · cloudflare/workers-sdk

jbwcloudflare · 2026-06-15T12:54:40Z

Fixes #WC-4107

Begin onboarding wrangler to use the improved API endpoint for uploading Workers Assets.
This is being staged as a gradual rollout:

By default, users will continue to use the existing wrangler codepath and API endpoint.
Users that are opted-in to the new feature (controlled on the server side) will use the new endpoint.

This allows us to gradually roll out and validate the new feature without a hard cutover during a new wrangler release, or the need for emergency wrangler patch releases if something goes wrong.

Tests
- Tests included/updated
- Automated tests not possible - manual testing has been completed as follows:
- Additional testing not necessary because:
Public documentation
- Cloudflare docs PR(s):
- Documentation not necessary because: not a new feature just an implementation detail change

A picture of a cute animal (not mandatory, but encouraged)

changeset-bot · 2026-06-15T12:54:46Z

🦋 Changeset detected

Latest commit: c48cd7c

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

This PR includes changesets to release 3 packages

Name	Type
wrangler	Patch
@cloudflare/vite-plugin	Patch
@cloudflare/vitest-pool-workers	Patch

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

pkg-pr-new · 2026-06-15T13:08:57Z

create-cloudflare

npm i https://pkg.pr.new/create-cloudflare@14305

@cloudflare/deploy-helpers

npm i https://pkg.pr.new/@cloudflare/deploy-helpers@14305

@cloudflare/kv-asset-handler

npm i https://pkg.pr.new/@cloudflare/kv-asset-handler@14305

miniflare

npm i https://pkg.pr.new/miniflare@14305

@cloudflare/pages-shared

npm i https://pkg.pr.new/@cloudflare/pages-shared@14305

@cloudflare/unenv-preset

npm i https://pkg.pr.new/@cloudflare/unenv-preset@14305

@cloudflare/vite-plugin

npm i https://pkg.pr.new/@cloudflare/vite-plugin@14305

@cloudflare/vitest-pool-workers

npm i https://pkg.pr.new/@cloudflare/vitest-pool-workers@14305

@cloudflare/workers-auth

npm i https://pkg.pr.new/@cloudflare/workers-auth@14305

@cloudflare/workers-editor-shared

npm i https://pkg.pr.new/@cloudflare/workers-editor-shared@14305

@cloudflare/workers-utils

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wrangler

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commit: c48cd7c

workers-devprod · 2026-06-15T14:09:50Z

Codeowners approval required for this PR:

@cloudflare/wrangler

Show detailed file reviewers

.changeset/edge-kv-asset-upload.md: [@cloudflare/wrangler]
packages/deploy-helpers/src/deploy/helpers/assets.ts: [@cloudflare/wrangler]
packages/deploy-helpers/src/deploy/helpers/jwt.ts: [@cloudflare/wrangler]
packages/wrangler/src/tests/deploy/assets.test.ts: [@cloudflare/wrangler]
packages/wrangler/src/tests/deploy/helpers.ts: [@cloudflare/wrangler]
packages/wrangler/src/pages/upload.ts: [@cloudflare/wrangler]

devin-ai-integration

Devin Review found 1 new potential issue.

devin-ai-integration · 2026-06-15T20:16:31Z

+export function getEdgeKvUploadConcurrency(jwt: string): number {
+	try {
+		const value = Number(decodeJwtPayload(jwt).edge_kv_upload_concurrency);
+		return value > 0 ? Math.floor(value) : EDGE_KV_UPLOAD_CONCURRENCY;


🟡 getEdgeKvUploadConcurrency can return 0 for fractional JWT values between 0 and 1, breaking PQueue

When edge_kv_upload_concurrency in the JWT is a fractional value in the range (0, 1) — e.g. 0.5 — the check value > 0 passes but Math.floor(value) produces 0. PQueue requires concurrency ≥ 1; setting it to 0 will cause the queue to either throw or hang indefinitely, preventing any uploads from completing. While the value is server-controlled (making this unlikely in practice), a simple guard like Math.max(1, Math.floor(value)) or checking value >= 1 would make this robust.

Suggested change

return value > 0 ? Math.floor(value) : EDGE_KV_UPLOAD_CONCURRENCY;

return value >= 1 ? Math.floor(value) : EDGE_KV_UPLOAD_CONCURRENCY;

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it's fine lol we will not set this to a fractional value between 0 and 1 on the server side

jbwcloudflare · 2026-06-17T19:09:24Z

-						},
-						body: payload,
+				let res: UploadResponse;
+				if (useEdgeKvUpload) {


this is the new codepath: if the gate is on, use the new single-file upload endpoint

jbwcloudflare · 2026-06-17T19:09:35Z

+						}
+					);
+				} else {
+					// Populate the payload only when actually uploading (this is limited to 3 concurrent uploads at 50 MiB per bucket meaning we'd only load in a max of ~150 MiB)


this is the old codepath: just moved down into the else

matthewdavidrodgers · 2026-06-17T19:20:52Z

+					const contentType = getContentType(absFilePath);
+					res = await fetchResult<UploadResponse>(
+						complianceConfig,
+						`/accounts/${accountId}/workers/assets/upload/${manifestEntry[1].hash}`,


didn't realize we were using the same endpoint but with different semantics, i kinda figured we'd have a new endpoint? not an issue though

the old bulk one is:
/accounts/${accountId}/workers/assets/upload,

and the new single file-one is:
/accounts/${accountId}/workers/assets/upload/:hash

so they are different, unless i'm misunderstanding the question?

matthewdavidrodgers · 2026-06-17T19:27:13Z

+
+	const queue = new PQueue({
+		concurrency: useEdgeKvUpload
+			? getEdgeKvUploadConcurrency(initializeAssetsResponse.jwt)


do we need concurrency limits for single-file uploads? i guess probably if there's any level of buffering, and definitely better start there and increase it.

not sure i'm following: edgeKvUpload is the single-file mode and this will currently set the concurrency limit to 25 by default (it's actually a setting in the JWT so we can increase it from EWC later if we want)

is that what you meant? or some kind of server side concurrency limit maybe?

workers-devprod added this to workers-sdk Jun 15, 2026

github-project-automation Bot moved this to Untriaged in workers-sdk Jun 15, 2026

jbwcloudflare force-pushed the wrangler-edge-kv-asset-upload branch from 5b5e896 to c549f98 Compare June 15, 2026 13:53

jbwcloudflare marked this pull request as ready for review June 15, 2026 14:09

jbwcloudflare requested a review from workers-devprod as a code owner June 15, 2026 14:09

workers-devprod requested review from a team and james-elicx and removed request for a team June 15, 2026 14:09

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jbwcloudflare force-pushed the wrangler-edge-kv-asset-upload branch from c549f98 to ba647bb Compare June 15, 2026 18:23

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jbwcloudflare force-pushed the wrangler-edge-kv-asset-upload branch from ba647bb to 13f5a9f Compare June 15, 2026 19:21

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jbwcloudflare marked this pull request as draft June 15, 2026 19:36

jbwcloudflare force-pushed the wrangler-edge-kv-asset-upload branch from 13f5a9f to 6676947 Compare June 15, 2026 19:42

jbwcloudflare marked this pull request as ready for review June 15, 2026 19:43

jbwcloudflare force-pushed the wrangler-edge-kv-asset-upload branch from 6676947 to 5d74650 Compare June 15, 2026 20:10

devin-ai-integration Bot reviewed Jun 15, 2026

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james-elicx marked this pull request as draft June 15, 2026 20:44

jbwcloudflare changed the title ~~[wrangler] Support Edge KV single-file asset uploads~~ [wrangler] Improve asset upload performance with single-file uploads Jun 16, 2026

[wrangler] Support Edge KV single-file asset uploads

c48cd7c

jbwcloudflare force-pushed the wrangler-edge-kv-asset-upload branch from 5d74650 to c48cd7c Compare June 17, 2026 19:04

jbwcloudflare commented Jun 17, 2026

View reviewed changes

matthewdavidrodgers approved these changes Jun 17, 2026

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	return value > 0 ? Math.floor(value) : EDGE_KV_UPLOAD_CONCURRENCY;
	return value >= 1 ? Math.floor(value) : EDGE_KV_UPLOAD_CONCURRENCY;

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jbwcloudflare commented Jun 15, 2026

This allows us to gradually roll out and validate the new feature without a hard cutover during a new wrangler release, or the need for emergency wrangler patch releases if something goes wrong.

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