Add errors for local links

docs/src/content/docs/configuration.md

@@ -125,6 +125,28 @@ export default defineConfig({
 })
 ```
 
+### `errorOnLocalLinks`
+
+**Type:** `boolean`  
+**Default:** `true`
+
+By default, the Starlight Links Validator plugin will error on local links, e.g. URLs with a hostname of `localhost` or `127.0.0.1`, as they are usually used for development purposes and should not be present in production.
+If you want to allow such links, you can set this option to `false`.
+
+```js {6}
+export default defineConfig({
+  integrations: [
+    starlight({
+      plugins: [
+        starlightLinksValidator({
+          errorOnLocalLinks: false,
+        }),
+      ],
+    }),
+  ],
+})
+```
+
 ### `exclude`
 
 **Type:** `string[]`  

packages/starlight-links-validator/index.ts

@@ -41,6 +41,12 @@ const starlightLinksValidatorOptionsSchema = z
      * @default true
      */
     errorOnInvalidHashes: z.boolean().default(true),
+    /**
+     * Defines whether the plugin should error on local links, e.g. URLs with a hostname of `localhost` or `127.0.0.1`.
+     *
+     * @default true
+     */
+    errorOnLocalLinks: z.boolean().default(true),
     /**
      * Defines a list of links or glob patterns that should be excluded from validation.
      *

packages/starlight-links-validator/libs/remark.ts

@@ -61,7 +61,7 @@ export const remarkStarlightLinksValidator: Plugin<[{ base: string; srcDir: URL
           break
         }
         case 'link': {
-          if (isInternalLink(node.url)) {
+          if (shouldValidateLink(node.url)) {
             fileLinks.push(node.url)
           }
 
@@ -70,7 +70,7 @@ export const remarkStarlightLinksValidator: Plugin<[{ base: string; srcDir: URL
         case 'linkReference': {
           const definition = fileDefinitions.get(node.identifier)
 
-          if (definition && isInternalLink(definition)) {
+          if (definition && shouldValidateLink(definition)) {
             fileLinks.push(definition)
           }
 
@@ -96,7 +96,7 @@ export const remarkStarlightLinksValidator: Plugin<[{ base: string; srcDir: URL
               continue
             }
 
-            if (isInternalLink(attribute.value)) {
+            if (shouldValidateLink(attribute.value)) {
               fileLinks.push(attribute.value)
             }
           }
@@ -125,7 +125,7 @@ export const remarkStarlightLinksValidator: Plugin<[{ base: string; srcDir: URL
               htmlNode.tagName === 'a' &&
               hasProperty(htmlNode, 'href') &&
               typeof htmlNode.properties.href === 'string' &&
-              isInternalLink(htmlNode.properties.href)
+              shouldValidateLink(htmlNode.properties.href)
             ) {
               fileLinks.push(htmlNode.properties.href)
             }
@@ -145,8 +145,18 @@ export function getValidationData() {
   return { headings, links }
 }
 
-function isInternalLink(link: string) {
-  return !isAbsoluteUrl(link)
+function shouldValidateLink(link: string) {
+  if (!isAbsoluteUrl(link)) {
+    return true
+  }
+
+  try {
+    const url = new URL(link)
+
+    return url.hostname === 'localhost' || url.hostname === '127.0.0.1'
+  } catch {
+    return false
+  }
 }
 
 function getFilePath(base: string, filePath: string, slug: string | undefined) {

packages/starlight-links-validator/libs/validation.ts

@@ -17,6 +17,7 @@ export const ValidationErrorType = {
   InconsistentLocale: 'inconsistent locale',
   InvalidHash: 'invalid hash',
   InvalidLink: 'invalid link',
+  LocalLink: 'local link',
   RelativeLink: 'relative link',
   TrailingSlash: 'trailing slash',
 } as const
@@ -115,6 +116,14 @@ function validateLink(context: ValidationContext) {
     return
   }
 
+  if (/^https?:\/\//.test(link)) {
+    if (options.errorOnLocalLinks) {
+      addError(errors, filePath, link, ValidationErrorType.LocalLink)
+    }
+
+    return
+  }
+
   const sanitizedLink = link.replace(/^\//, '')
   const segments = sanitizedLink.split('#')
 

packages/starlight-links-validator/tests/basics.test.ts

@@ -21,7 +21,7 @@ test('does not build with invalid links', async () => {
 
   expect(status).toBe('error')
 
-  expectValidationErrorCount(output, 61, 4)
+  expectValidationErrorCount(output, 64, 4)
 
   expectValidationErrors(output, 'test/', [
     ['/https://starlight.astro.build/', ValidationErrorType.InvalidLink],
@@ -52,6 +52,9 @@ test('does not build with invalid links', async () => {
     ['/guidelines/ui.pdf?query=string', ValidationErrorType.InvalidLink],
     ['/unknown-ref?query=string', ValidationErrorType.InvalidLink],
     ['?query=string#unknown-ref', ValidationErrorType.InvalidHash],
+    ['http://localhost', ValidationErrorType.LocalLink],
+    ['http://localhost:4321/', ValidationErrorType.LocalLink],
+    ['https://127.0.0.1:4321/getting-started', ValidationErrorType.LocalLink],
   ])
 
   expectValidationErrors(output, 'guides/example/', [

packages/starlight-links-validator/tests/fixtures/invalid-links/src/content/docs/test.md

@@ -77,3 +77,9 @@ some content
 
 [ref-with-query-string-unknown-page]: /unknown-ref?query=string
 [ref-with-query-string-invalid-hash]: ?query=string#unknown-ref
+
+## Local links
+
+- [Local link](http://localhost)
+- [Local link with port](http://localhost:4321/)
+- [Local link using HTTPS](https://127.0.0.1:4321/getting-started)