Add sourcemapBaseUrl option (#4527)

* Add sourcemapBaseUrl option

* Use sourcemapBaseUrl if it's present

* Add tests

* Update docs

* Run lint

* Extend documentation, add bad URL test

* Align CLI docs

Co-authored-by: Lukas Taegert-Atkinson <lukas.taegert-atkinson@tngtech.com>

cli/help.md

@@ -54,6 +54,7 @@ Basic options:
 --no-sanitizeFileName       Do not replace invalid characters in file names
 --shimMissingExports        Create shim variables for missing exports
 --silent                    Don't print warnings
+--sourcemapBaseUrl <url>    Emit absolute sourcemap URLs with given base
 --sourcemapExcludeSources   Do not include source code in source maps
 --sourcemapFile <file>      Specify bundle position for source maps
 --stdin=ext                 Specify file extension used for stdin input

docs/01-command-line-reference.md

@@ -90,6 +90,7 @@ export default {
     preserveModules,
     preserveModulesRoot,
     sourcemap,
+    sourcemapBaseUrl,
     sourcemapExcludeSources,
     sourcemapFile,
     sourcemapPathTransform,
@@ -360,6 +361,7 @@ Many options have command line equivalents. In those cases, any arguments passed
 --no-sanitizeFileName       Do not replace invalid characters in file names
 --shimMissingExports        Create shim variables for missing exports
 --silent                    Don't print warnings
+--sourcemapBaseUrl <url>    Emit absolute sourcemap URLs with given base
 --sourcemapExcludeSources   Do not include source code in source maps
 --sourcemapFile <file>      Specify bundle position for source maps
 --stdin=ext                 Specify file extension used for stdin input

docs/999-big-list-of-options.md

@@ -1075,11 +1075,17 @@ Type: `boolean | 'inline' | 'hidden'`<br> CLI: `-m`/`--sourcemap`/`--no-sourcema
 
 If `true`, a separate sourcemap file will be created. If `"inline"`, the sourcemap will be appended to the resulting `output` file as a data URI. `"hidden"` works like `true` except that the corresponding sourcemap comments in the bundled files are suppressed.
 
+### output.sourcemapBaseUrl
+
+Type: `string`<br> CLI: `--sourcemapBaseUrl <url>`
+
+By default, sourcemap files generated by Rollup uses relative URLs to reference the files they describe. By providing an absolute base URL, e.g. `https://example.com`, sourcemaps will use absolute URLs instead.
+
 #### output.sourcemapExcludeSources
 
 Type: `boolean`<br> CLI: `--sourcemapExcludeSources`/`--no-sourcemapExcludeSources`<br> Default: `false`
 
-If `true`, the actual code of the sources will not be added to the sourcemaps making them considerably smaller.
+If `true`, the actual code of the sources will not be added to the sourcemaps, making them considerably smaller.
 
 #### output.sourcemapFile
 

src/rollup/rollup.ts

@@ -284,7 +284,11 @@ async function writeOutputFile(
 			if (outputOptions.sourcemap === 'inline') {
 				url = outputFile.map.toUrl();
 			} else {
-				url = `${basename(outputFile.fileName)}.map`;
+				const { sourcemapBaseUrl } = outputOptions;
+				const sourcemapFileName = `${basename(outputFile.fileName)}.map`;
+				url = sourcemapBaseUrl
+					? new URL(sourcemapFileName, sourcemapBaseUrl).toString()
+					: sourcemapFileName;
 				writeSourceMapPromise = fs.writeFile(`${fileName}.map`, outputFile.map.toString());
 			}
 			if (outputOptions.sourcemap !== 'hidden') {

src/rollup/types.d.ts

@@ -692,6 +692,7 @@ export interface OutputOptions {
 	preserveModulesRoot?: string;
 	sanitizeFileName?: boolean | ((fileName: string) => string);
 	sourcemap?: boolean | 'inline' | 'hidden';
+	sourcemapBaseUrl?: string;
 	sourcemapExcludeSources?: boolean;
 	sourcemapFile?: string;
 	sourcemapPathTransform?: SourcemapPathTransformOption;
@@ -739,6 +740,7 @@ export interface NormalizedOutputOptions {
 	preserveModulesRoot: string | undefined;
 	sanitizeFileName: (fileName: string) => string;
 	sourcemap: boolean | 'inline' | 'hidden';
+	sourcemapBaseUrl: string | undefined;
 	sourcemapExcludeSources: boolean;
 	sourcemapFile: string | undefined;
 	sourcemapPathTransform: SourcemapPathTransformOption | undefined;

src/utils/options/mergeOptions.ts

@@ -263,6 +263,7 @@ function mergeOutputOptions(
 		preserveModulesRoot: getOption('preserveModulesRoot'),
 		sanitizeFileName: getOption('sanitizeFileName'),
 		sourcemap: getOption('sourcemap'),
+		sourcemapBaseUrl: getOption('sourcemapBaseUrl'),
 		sourcemapExcludeSources: getOption('sourcemapExcludeSources'),
 		sourcemapFile: getOption('sourcemapFile'),
 		sourcemapPathTransform: getOption('sourcemapPathTransform'),

src/utils/options/normalizeOutputOptions.ts

@@ -10,6 +10,7 @@ import { ensureArray } from '../ensureArray';
 import { errInvalidExportOptionValue, errInvalidOption, error, warnDeprecation } from '../error';
 import { resolve } from '../path';
 import { sanitizeFileName as defaultSanitizeFileName } from '../sanitizeFileName';
+import { isValidUrl } from '../url';
 import {
 	generatedCodePresets,
 	type GenericConfigObject,
@@ -76,6 +77,7 @@ export function normalizeOutputOptions(
 				? id => id
 				: defaultSanitizeFileName,
 		sourcemap: config.sourcemap || false,
+		sourcemapBaseUrl: getSourcemapBaseUrl(config),
 		sourcemapExcludeSources: config.sourcemapExcludeSources || false,
 		sourcemapFile: config.sourcemapFile,
 		sourcemapPathTransform: config.sourcemapPathTransform as
@@ -471,3 +473,21 @@ const getNamespaceToStringTag = (
 	}
 	return generatedCode.symbols || false;
 };
+
+const getSourcemapBaseUrl = (
+	config: OutputOptions
+): NormalizedOutputOptions['sourcemapBaseUrl'] => {
+	const { sourcemapBaseUrl } = config;
+	if (sourcemapBaseUrl) {
+		if (isValidUrl(sourcemapBaseUrl)) {
+			return sourcemapBaseUrl;
+		}
+		return error(
+			errInvalidOption(
+				'output.sourcemapBaseUrl',
+				'outputsourcemapbaseurl',
+				`must be a valid URL, received ${JSON.stringify(sourcemapBaseUrl)}`
+			)
+		);
+	}
+};

src/utils/url.ts

@@ -0,0 +1,8 @@
+export function isValidUrl(url: string): boolean {
+	try {
+		new URL(url);
+	} catch (_) {
+		return false;
+	}
+	return true;
+}

test/function/samples/sourcemap-base-url-invalid/_config.js

@@ -0,0 +1,14 @@
+module.exports = {
+	description: 'throws for invalid sourcemapBaseUrl',
+	options: {
+		output: {
+			sourcemapBaseUrl: 'example.com'
+		}
+	},
+	generateError: {
+		code: 'INVALID_OPTION',
+		message:
+			'Invalid value for option "output.sourcemapBaseUrl" - must be a valid URL, received "example.com".',
+		url: 'https://rollupjs.org/guide/en/#outputsourcemapbaseurl'
+	}
+};

test/function/samples/sourcemap-base-url-invalid/main.js

@@ -0,0 +1 @@
+console.log( 42 );

test/sourcemaps/samples/sourcemap-base-url/_config.js

@@ -0,0 +1,22 @@
+const assert = require('assert');
+const fs = require('fs');
+const path = require('path');
+
+module.exports = {
+	description: 'adds a sourcemap base url',
+	options: {
+		output: {
+			sourcemapBaseUrl: 'https://example.com'
+		}
+	},
+	test: (code, map, profile) => {
+		assert.equal(map.file, `bundle.${profile.format}.js`);
+		const bundlePath = path.join(__dirname, `_actual/bundle.${profile.format}.js`);
+		const bundledCode = fs.readFileSync(bundlePath, { encoding: 'utf8', flag: 'r' });
+		const sourceMappingURL = bundledCode.split('\n').slice(-2)[0];
+		assert.equal(
+			sourceMappingURL,
+			`//# sourceMappingURL=https://example.com/bundle.${profile.format}.js.map`
+		);
+	}
+};

test/sourcemaps/samples/sourcemap-base-url/main.js

@@ -0,0 +1 @@
+console.log( 42 );