fix: allow assets in multiworker setup (#7290)

* multidev assets

* assert rpc and named entrypoints do not work

* fixups

* fixup bindings earlier

* aaaaargh

* don't touch sockets

Author: emily-shen

.changeset/poor-otters-drop.md

@@ -0,0 +1,10 @@
+---
+"miniflare": patch
+"wrangler": patch
+---
+
+fix: add support for workers with assets when running multiple workers in one `wrangler dev` instance
+
+https://github.com/cloudflare/workers-sdk/pull/7251 added support for running multiple Workers in one `wrangler dev`/miniflare session. e.g. `wrangler dev -c wrangler.toml -c ../worker2/wrangler.toml`, which among other things, allowed cross-service RPC to Durable Objects.
+
+However this did not work in the same way as production when there was a Worker with assets - this PR should fix that.

packages/miniflare/src/index.ts

@@ -1130,14 +1130,6 @@ export class Miniflare {
 			innerBindings: Worker_Binding[];
 		}[] = [];
 
-		if (this.#workerOpts[0].assets.assets) {
-			// This will be the UserWorker, or the vitest pool worker wrapping the UserWorker
-			// The asset plugin needs this so that it can set the binding between the RouterWorker and the UserWorker
-			// TODO: apply this to ever this.#workerOpts, not just the first (i.e this.#workerOpts[0])
-			this.#workerOpts[0].assets.assets.workerName =
-				this.#workerOpts[0].core.name;
-		}
-
 		for (let i = 0; i < allWorkerOpts.length; i++) {
 			const previousWorkerOpts = allPreviousWorkerOpts?.[i];
 			const workerOpts = allWorkerOpts[i];
@@ -1152,6 +1144,12 @@ export class Miniflare {
 				}
 			}
 
+			if (workerOpts.assets.assets) {
+				// This will be the UserWorker, or the vitest pool worker wrapping the UserWorker
+				// The asset plugin needs this so that it can set the binding between the RouterWorker and the UserWorker
+				workerOpts.assets.assets.workerName = workerOpts.core.name;
+			}
+
 			// Collect all bindings from this worker
 			const workerBindings: Worker_Binding[] = [];
 			allWorkerBindings.set(workerName, workerBindings);
@@ -1202,6 +1200,20 @@ export class Miniflare {
 								});
 							}
 						}
+						if ("service" in binding) {
+							const targetWorkerName = binding.service?.name?.replace(
+								"core:user:",
+								""
+							);
+							const maybeAssetTargetService = allWorkerOpts.find(
+								(worker) =>
+									worker.core.name === targetWorkerName && worker.assets.assets
+							);
+							if (maybeAssetTargetService) {
+								assert(binding.service?.name);
+								binding.service.name = `${ROUTER_SERVICE_NAME}:${targetWorkerName}`;
+							}
+						}
 					}
 				}
 			}
@@ -1305,7 +1317,7 @@ export class Miniflare {
 				!this.#workerOpts[0].core.name?.startsWith(
 					"vitest-pool-workers-runner-"
 				)
-					? ROUTER_SERVICE_NAME
+					? `${ROUTER_SERVICE_NAME}:${this.#workerOpts[0].core.name}`
 					: getUserServiceName(this.#workerOpts[0].core.name),
 			loopbackPort,
 			log: this.#log,
@@ -1340,7 +1352,6 @@ export class Miniflare {
 					"Ensure wrapped bindings don't have bindings to themselves."
 			);
 		}
-
 		return { services: servicesArray, sockets, extensions };
 	}
 

packages/miniflare/src/plugins/assets/index.ts

@@ -39,7 +39,9 @@ export const ASSETS_PLUGIN: Plugin<typeof AssetsOptionsSchema> = {
 			{
 				// binding between User Worker and Asset Worker
 				name: options.assets.binding,
-				service: { name: ASSETS_SERVICE_NAME },
+				service: {
+					name: `${ASSETS_SERVICE_NAME}:${options.assets.workerName}`,
+				},
 			},
 		];
 	},
@@ -68,8 +70,10 @@ export const ASSETS_PLUGIN: Plugin<typeof AssetsOptionsSchema> = {
 			options.assets.directory
 		);
 
+		const id = options.assets.workerName;
+
 		const namespaceService: Service = {
-			name: ASSETS_KV_SERVICE_NAME,
+			name: `${ASSETS_KV_SERVICE_NAME}:${id}`,
 			worker: {
 				compatibilityDate: "2023-07-24",
 				compatibilityFlags: ["nodejs_compat"],
@@ -93,7 +97,7 @@ export const ASSETS_PLUGIN: Plugin<typeof AssetsOptionsSchema> = {
 		};
 
 		const assetService: Service = {
-			name: ASSETS_SERVICE_NAME,
+			name: `${ASSETS_SERVICE_NAME}:${id}`,
 			worker: {
 				compatibilityDate: "2024-08-01",
 				modules: [
@@ -105,7 +109,9 @@ export const ASSETS_PLUGIN: Plugin<typeof AssetsOptionsSchema> = {
 				bindings: [
 					{
 						name: "ASSETS_KV_NAMESPACE",
-						kvNamespace: { name: ASSETS_KV_SERVICE_NAME },
+						kvNamespace: {
+							name: `${ASSETS_KV_SERVICE_NAME}:${id}`,
+						},
 					},
 					{
 						name: "ASSETS_MANIFEST",
@@ -120,7 +126,7 @@ export const ASSETS_PLUGIN: Plugin<typeof AssetsOptionsSchema> = {
 		};
 
 		const routerService: Service = {
-			name: ROUTER_SERVICE_NAME,
+			name: `${ROUTER_SERVICE_NAME}:${id}`,
 			worker: {
 				compatibilityDate: "2024-08-01",
 				modules: [
@@ -132,11 +138,13 @@ export const ASSETS_PLUGIN: Plugin<typeof AssetsOptionsSchema> = {
 				bindings: [
 					{
 						name: "ASSET_WORKER",
-						service: { name: ASSETS_SERVICE_NAME },
+						service: {
+							name: `${ASSETS_SERVICE_NAME}:${id}`,
+						},
 					},
 					{
 						name: "USER_WORKER",
-						service: { name: getUserServiceName(options.assets.workerName) },
+						service: { name: getUserServiceName(id) },
 					},
 					{
 						name: "CONFIG",

packages/miniflare/src/plugins/core/index.ts

@@ -262,7 +262,7 @@ function getCustomServiceDesignator(
 	} else if (service === kCurrentWorker) {
 		// Sets SELF binding to point to router worker instead if assets are present.
 		serviceName = hasAssetsAndIsVitest
-			? ROUTER_SERVICE_NAME
+			? `${ROUTER_SERVICE_NAME}:${refererName}`
 			: getUserServiceName(refererName);
 	} else {
 		// Regular user worker