Add warning for smart placement w/assets (#7568)

* Provide validation around experimental_serve_directly usage in dev and deploy

* Update based on PR feedback

Author: WillTaylorDev

.changeset/tidy-kiwis-arrive.md

@@ -0,0 +1,5 @@
+---
+"wrangler": minor
+---
+
+Warn users when using smart placement with Workers + Assets and `serve_directly` is set to `false`

packages/wrangler/src/__tests__/deploy.test.ts

@@ -4687,6 +4687,55 @@ addEventListener('fetch', event => {});`
 			`);
 		});
 
+		it("should warn when using smart placement with Worker first", async () => {
+			const assets = [
+				{ filePath: ".assetsignore", content: "*.bak\nsub-dir" },
+				{ filePath: "file-1.txt", content: "Content of file-1" },
+				{ filePath: "file-2.bak", content: "Content of file-2" },
+				{ filePath: "file-3.txt", content: "Content of file-3" },
+				{ filePath: "sub-dir/file-4.bak", content: "Content of file-4" },
+				{ filePath: "sub-dir/file-5.txt", content: "Content of file-5" },
+			];
+			writeAssets(assets, "assets");
+			writeWorkerSource({ format: "js" });
+			writeWranglerConfig({
+				main: "index.js",
+				assets: {
+					directory: "assets",
+					experimental_serve_directly: false,
+					binding: "ASSETS",
+				},
+				placement: {
+					mode: "smart",
+				},
+			});
+			const bodies: AssetManifest[] = [];
+			await mockAUSRequest(bodies);
+			mockSubDomainRequest();
+			mockUploadWorkerRequest({
+				expectedAssets: {
+					jwt: "<<aus-completion-token>>",
+					config: {
+						serve_directly: false,
+					},
+				},
+				expectedMainModule: "index.js",
+				expectedBindings: [{ name: "ASSETS", type: "assets" }],
+			});
+
+			await runWrangler("deploy");
+
+			expect(std.warn).toMatchInlineSnapshot(`
+				"▲ [WARNING] Turning on Smart Placement in a Worker that is using assets and serve_directly set to false means that your entire Worker could be moved to run closer to your data source, and all requests will go to that Worker before serving assets.
+
+				  This could result in poor performance as round trip times could increase when serving assets.
+
+				  Read more: https://developers.cloudflare.com/workers/static-assets/binding/#smart-placement
+
+				"
+			`);
+		});
+
 		it("should warn if experimental_serve_directly=false but no binding is provided", async () => {
 			const assets = [
 				{ filePath: ".assetsignore", content: "*.bak\nsub-dir" },

packages/wrangler/src/assets.ts

@@ -444,6 +444,18 @@ export function validateAssetsArgsAndConfig(
 		);
 	}
 
+	// Smart placement turned on when using assets
+	if (
+		config?.placement?.mode === "smart" &&
+		config?.assets?.experimental_serve_directly === false
+	) {
+		logger.warn(
+			"Turning on Smart Placement in a Worker that is using assets and serve_directly set to false means that your entire Worker could be moved to run closer to your data source, and all requests will go to that Worker before serving assets.\n" +
+				"This could result in poor performance as round trip times could increase when serving assets.\n\n" +
+				"Read more: https://developers.cloudflare.com/workers/static-assets/binding/#smart-placement"
+		);
+	}
+
 	// User Worker ahead of assets, but no assets binding provided
 	if (
 		"legacy" in args