Add option to allow all URLs to be crawlable via robots.txt

CHANGELOG.md

@@ -4,6 +4,23 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com), and this project adheres to [Semantic Versioning](https://semver.org).
 
+## [Unreleased]
+### Added
+* [#2018](https://github.com/shlinkio/shlink/issues/2018) Add option to allow all short URLs to be unconditionally crawlable in robots.txt, via `ROBOTS_ALLOW_ALL_SHORT_URLS=true` env var, or config options.
+
+### Changed
+* *Nothing*
+
+### Deprecated
+* *Nothing*
+
+### Removed
+* *Nothing*
+
+### Fixed
+* *Nothing*
+
+
 ## [4.1.0] - 2024-04-14
 ### Added
 * [#1330](https://github.com/shlinkio/shlink/issues/1330) All visit-related endpoints now expose the `visitedUrl` prop for any visit.

composer.json

@@ -47,7 +47,7 @@
         "shlinkio/shlink-config": "^3.0",
         "shlinkio/shlink-event-dispatcher": "^4.1",
         "shlinkio/shlink-importer": "^5.3.2",
-        "shlinkio/shlink-installer": "^9.1",
+        "shlinkio/shlink-installer": "dev-develop#11e66d8 as 9.2",
         "shlinkio/shlink-ip-geolocation": "^4.0",
         "shlinkio/shlink-json": "^1.1",
         "spiral/roadrunner": "^2023.3",

config/autoload/installer.global.php

@@ -45,6 +45,7 @@ return [
             Option\UrlShortener\EnableMultiSegmentSlugsConfigOption::class,
             Option\UrlShortener\EnableTrailingSlashConfigOption::class,
             Option\UrlShortener\ShortUrlModeConfigOption::class,
+            Option\UrlShortener\RobotsAllowAllShortUrlsConfigOption::class,
             Option\Tracking\IpAnonymizationConfigOption::class,
             Option\Tracking\OrphanVisitsTrackingConfigOption::class,
             Option\Tracking\DisableTrackParamConfigOption::class,

config/autoload/robots.global.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shlinkio\Shlink\Core;
+
+return [
+
+    'robots' => [
+        'allow-all-short-urls' => (bool) Config\EnvVars::ROBOTS_ALLOW_ALL_SHORT_URLS->loadFromEnv(false),
+    ],
+
+];

module/Core/config/dependencies.config.php

@@ -189,7 +189,7 @@ return [
             'Logger_Shlink',
             Options\QrCodeOptions::class,
         ],
-        Action\RobotsAction::class => [Crawling\CrawlingHelper::class],
+        Action\RobotsAction::class => [Crawling\CrawlingHelper::class, 'config.robots.allow-all-short-urls'],
 
         ShortUrl\Resolver\PersistenceShortUrlRelationResolver::class => [
             'em',

module/Core/src/Action/RobotsAction.php

@@ -15,9 +15,9 @@ use function sprintf;
 
 use const PHP_EOL;
 
-class RobotsAction implements RequestHandlerInterface, StatusCodeInterface
+readonly class RobotsAction implements RequestHandlerInterface, StatusCodeInterface
 {
-    public function __construct(private readonly CrawlingHelperInterface $crawlingHelper)
+    public function __construct(private CrawlingHelperInterface $crawlingHelper, private bool $allowAllShortUrls)
     {
     }
 
@@ -37,6 +37,12 @@ class RobotsAction implements RequestHandlerInterface, StatusCodeInterface
 
         ROBOTS;
 
+        if ($this->allowAllShortUrls) {
+            // Disallow rest URLs, but allow all short codes
+            yield 'Disallow: /rest/';
+            return;
+        }
+
         $shortCodes = $this->crawlingHelper->listCrawlableShortCodes();
         foreach ($shortCodes as $shortCode) {
             yield sprintf('Allow: /%s%s', $shortCode, PHP_EOL);

module/Core/src/Config/EnvVars.php

@@ -69,8 +69,9 @@ enum EnvVars: string
     case DEFAULT_DOMAIN = 'DEFAULT_DOMAIN';
     case AUTO_RESOLVE_TITLES = 'AUTO_RESOLVE_TITLES';
     case REDIRECT_APPEND_EXTRA_PATH = 'REDIRECT_APPEND_EXTRA_PATH';
-    case TIMEZONE = 'TIMEZONE';
     case MULTI_SEGMENT_SLUGS_ENABLED = 'MULTI_SEGMENT_SLUGS_ENABLED';
+    case ROBOTS_ALLOW_ALL_SHORT_URLS = 'ROBOTS_ALLOW_ALL_SHORT_URLS';
+    case TIMEZONE = 'TIMEZONE';
     case MEMORY_LIMIT = 'MEMORY_LIMIT';
 
     public function loadFromEnv(mixed $default = null): mixed

module/Core/test/Action/RobotsActionTest.php

@@ -14,24 +14,25 @@ use Shlinkio\Shlink\Core\Crawling\CrawlingHelperInterface;
 
 class RobotsActionTest extends TestCase
 {
-    private RobotsAction $action;
     private MockObject & CrawlingHelperInterface $helper;
 
     protected function setUp(): void
     {
         $this->helper = $this->createMock(CrawlingHelperInterface::class);
-        $this->action = new RobotsAction($this->helper);
     }
 
     #[Test, DataProvider('provideShortCodes')]
-    public function buildsRobotsLinesFromCrawlableShortCodes(array $shortCodes, string $expected): void
-    {
+    public function buildsRobotsLinesFromCrawlableShortCodes(
+        array $shortCodes,
+        bool $allowAllShortUrls,
+        string $expected,
+    ): void {
         $this->helper
-            ->expects($this->once())
+            ->expects($allowAllShortUrls ? $this->never() : $this->once())
             ->method('listCrawlableShortCodes')
             ->willReturn($shortCodes);
 
-        $response = $this->action->handle(ServerRequestFactory::fromGlobals());
+        $response = $this->action($allowAllShortUrls)->handle(ServerRequestFactory::fromGlobals());
 
         self::assertEquals(200, $response->getStatusCode());
         self::assertEquals($expected, $response->getBody()->__toString());
@@ -40,7 +41,7 @@ class RobotsActionTest extends TestCase
 
     public static function provideShortCodes(): iterable
     {
-        yield 'three short codes' => [['foo', 'bar', 'baz'], <<<ROBOTS
+        yield 'three short codes' => [['foo', 'bar', 'baz'], false, <<<ROBOTS
         # For more information about the robots.txt standard, see:
         # https://www.robotstxt.org/orig.html
 
@@ -50,7 +51,7 @@ class RobotsActionTest extends TestCase
         Allow: /baz
         Disallow: /
         ROBOTS];
-        yield 'five short codes' => [['foo', 'bar', 'some', 'thing', 'baz'], <<<ROBOTS
+        yield 'five short codes' => [['foo', 'bar', 'some', 'thing', 'baz'], false, <<<ROBOTS
         # For more information about the robots.txt standard, see:
         # https://www.robotstxt.org/orig.html
 
@@ -62,12 +63,31 @@ class RobotsActionTest extends TestCase
         Allow: /baz
         Disallow: /
         ROBOTS];
-        yield 'no short codes' => [[], <<<ROBOTS
+        yield 'no short codes' => [[], false, <<<ROBOTS
         # For more information about the robots.txt standard, see:
         # https://www.robotstxt.org/orig.html
 
         User-agent: *
         Disallow: /
         ROBOTS];
+        yield 'three short codes and allow all short urls' => [['foo', 'bar', 'some'], true, <<<ROBOTS
+        # For more information about the robots.txt standard, see:
+        # https://www.robotstxt.org/orig.html
+
+        User-agent: *
+        Disallow: /rest/
+        ROBOTS];
+        yield 'no short codes and allow all short urls' => [[], true, <<<ROBOTS
+        # For more information about the robots.txt standard, see:
+        # https://www.robotstxt.org/orig.html
+
+        User-agent: *
+        Disallow: /rest/
+        ROBOTS];
+    }
+
+    private function action(bool $allowAllShortUrls = false): RobotsAction
+    {
+        return new RobotsAction($this->helper, allowAllShortUrls: $allowAllShortUrls);
     }
 }