feat: support Cloudflare Workers Builds

.changeset/plenty-cougars-wave.md

@@ -0,0 +1,6 @@
+---
+'@sveltejs/adapter-cloudflare': minor
+'@sveltejs/adapter-auto': minor
+---
+
+feat: support Cloudflare Workers Builds by detecting the `WORKERS_CI` environment variable

packages/adapter-auto/adapters.js

@@ -11,7 +11,7 @@ export const adapters = [
 	},
 	{
 		name: 'Cloudflare Pages',
-		test: () => !!process.env.CF_PAGES,
+		test: () => !!process.env.WORKERS_CI || !!process.env.CF_PAGES,
 		module: '@sveltejs/adapter-cloudflare',
 		version: '7'
 	},

packages/adapter-auto/index.js

@@ -84,7 +84,7 @@ async function get_adapter() {
 
 				console.log(`Successfully installed ${match.module}.`);
 				console.warn(
-					`\nIf you plan on staying on this deployment platform, consider replacing @sveltejs/adapter-auto with ${match.module}. This will give you faster and more robust installs, and more control over deployment configuration.\n`
+					`\nIf you plan on staying on this deployment platform, consider replacing @sveltejs/adapter-auto with ${match.module}. This will give you faster installs and more control over deployment configuration.\n`
 				);
 			} catch (e) {
 				throw new Error(

packages/adapter-cloudflare/index.js

@@ -27,8 +27,7 @@ export default function (options = {}) {
 				);
 			}
 
-			const wrangler_config = validate_config(options.config);
-			const building_for_cloudflare_pages = is_building_for_cloudflare_pages(wrangler_config);
+			const { wrangler_config, building_for_cloudflare_pages } = validate_config(options.config);
 
 			let dest = builder.getBuildDirectory('cloudflare');
 			let worker_dest = `${dest}/_worker.js`;
@@ -266,52 +265,59 @@ _redirects
 
 /**
  * @param {string} config_file
- * @returns {import('wrangler').Unstable_Config}
+ * @returns {{
+ * 	wrangler_config: import('wrangler').Unstable_Config,
+ * 	building_for_cloudflare_pages: boolean
+ * }}
  */
 function validate_config(config_file = undefined) {
 	const wrangler_config = unstable_readConfig({ config: config_file });
 
-	// we don't support workers sites
+	const wrangler_file = wrangler_config.configPath || 'your wrangler.jsonc file';
+
+	// we don't support Workers Sites
 	if (wrangler_config.site) {
 		throw new Error(
-			`You must remove all \`site\` keys in ${wrangler_config.configPath}. Consult https://svelte.dev/docs/kit/adapter-cloudflare#Migrating-from-Workers-Sites-to-Workers-Static-Assets`
+			`You must remove all \`site\` keys in ${wrangler_file}. Consult https://svelte.dev/docs/kit/adapter-cloudflare#Migrating-from-Workers-Sites-to-Workers-Static-Assets`
 		);
 	}
 
+	// we don't need to validate the config if we're building for Cloudflare Pages
+	// because the `main` and `assets` values cannot be changed
 	if (is_building_for_cloudflare_pages(wrangler_config)) {
-		return wrangler_config;
+		return {
+			wrangler_config,
+			building_for_cloudflare_pages: true
+		};
 	}
 
-	// probably deploying to Cloudflare Workers
-	if (wrangler_config.main || wrangler_config.assets) {
-		if (!wrangler_config.assets?.directory) {
-			throw new Error(
-				`You must specify the \`assets.directory\` key in ${wrangler_config.configPath}. Consult https://developers.cloudflare.com/workers/static-assets/binding/#directory`
-			);
-		}
+	if (!wrangler_config.assets?.directory) {
+		throw new Error(
+			`You must specify the \`assets.directory\` key in ${wrangler_file}. Consult https://developers.cloudflare.com/workers/static-assets/binding/#directory`
+		);
+	}
 
-		if (!wrangler_config.assets?.binding) {
-			throw new Error(
-				`You must specify the \`assets.binding\` key in ${wrangler_config.configPath}. Consult https://developers.cloudflare.com/workers/static-assets/binding/#binding`
-			);
-		}
+	if (!wrangler_config.assets?.binding) {
+		throw new Error(
+			`You must specify the \`assets.binding\` key in ${wrangler_file}. Consult https://developers.cloudflare.com/workers/static-assets/binding/#binding`
+		);
 	}
 
-	return wrangler_config;
+	return {
+		wrangler_config,
+		building_for_cloudflare_pages: false
+	};
 }
 
 /**
  * @param {import('wrangler').Unstable_Config} wrangler_config
  * @returns {boolean}
  */
 function is_building_for_cloudflare_pages(wrangler_config) {
-	return (
-		!!process.env.CF_PAGES ||
-		!wrangler_config.configPath ||
-		!!wrangler_config.pages_build_output_dir ||
-		!wrangler_config.main ||
-		!wrangler_config.assets
-	);
+	if (!!process.env.WORKERS_CI || wrangler_config.main || wrangler_config.assets) {
+		return false;
+	}
+	return true;
 }
 
 /** @param {string} str */