Add option to customize user agents in robots.txt

CHANGELOG.md

@@ -6,7 +6,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com), and this
 
 ## [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.
+* [#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 option.
+* [#2109](https://github.com/shlinkio/shlink/issues/2109) Add option to customize user agents robots.txt, via `ROBOTS_USER_AGENTS=foo,bar,baz` env var, or config option.
 
 ### Changed
 * [#2096](https://github.com/shlinkio/shlink/issues/2096) Update to RoadRunner 2024.

config/autoload/robots.global.php

@@ -8,6 +8,7 @@ return [
 
     'robots' => [
         'allow-all-short-urls' => (bool) Config\EnvVars::ROBOTS_ALLOW_ALL_SHORT_URLS->loadFromEnv(false),
+        'user-agents' => splitByComma(Config\EnvVars::ROBOTS_USER_AGENTS->loadFromEnv()),
     ],
 
 ];

config/autoload/tracking.global.php

@@ -4,9 +4,7 @@ declare(strict_types=1);
 
 use Shlinkio\Shlink\Core\Config\EnvVars;
 
-return (static function (): array {
-    /** @var string|null $disableTrackingFrom */
-    $disableTrackingFrom = EnvVars::DISABLE_TRACKING_FROM->loadFromEnv();
+use function Shlinkio\Shlink\Core\splitByComma;
 
 return [
 
@@ -34,10 +32,7 @@ return (static function (): array {
         'disable_ua_tracking' => (bool) EnvVars::DISABLE_UA_TRACKING->loadFromEnv(false),
 
         // A list of IP addresses, patterns or CIDR blocks from which tracking is disabled by default
-            'disable_tracking_from' => $disableTrackingFrom === null
-                ? []
-                : array_map(trim(...), explode(',', $disableTrackingFrom)),
+        'disable_tracking_from' => splitByComma(EnvVars::DISABLE_TRACKING_FROM->loadFromEnv()),
     ],
 
 ];
-})();

module/Core/config/dependencies.config.php

@@ -32,6 +32,7 @@ return [
             Options\TrackingOptions::class => [ValinorConfigFactory::class, 'config.tracking'],
             Options\QrCodeOptions::class => [ValinorConfigFactory::class, 'config.qr_codes'],
             Options\RabbitMqOptions::class => [ValinorConfigFactory::class, 'config.rabbitmq'],
+            Options\RobotsOptions::class => [ValinorConfigFactory::class, 'config.robots'],
 
             RedirectRule\ShortUrlRedirectRuleService::class => ConfigAbstractFactory::class,
             RedirectRule\ShortUrlRedirectionResolver::class => ConfigAbstractFactory::class,
@@ -189,7 +190,7 @@ return [
             'Logger_Shlink',
             Options\QrCodeOptions::class,
         ],
-        Action\RobotsAction::class => [Crawling\CrawlingHelper::class, 'config.robots.allow-all-short-urls'],
+        Action\RobotsAction::class => [Crawling\CrawlingHelper::class, Options\RobotsOptions::class],
 
         ShortUrl\Resolver\PersistenceShortUrlRelationResolver::class => [
             'em',

module/Core/functions/functions.php

@@ -260,3 +260,16 @@ function enumToString(string $enum): string
 {
     return sprintf('["%s"]', implode('", "', enumValues($enum)));
 }
+
+/**
+ * Split provided string by comma and return a list of the results.
+ * An empty array is returned if provided value is empty
+ */
+function splitByComma(?string $value): array
+{
+    if ($value === null || trim($value) === '') {
+        return [];
+    }
+
+    return array_map(trim(...), explode(',', $value));
+}

module/Core/src/Action/RobotsAction.php

@@ -10,6 +10,7 @@ use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
 use Psr\Http\Server\RequestHandlerInterface;
 use Shlinkio\Shlink\Core\Crawling\CrawlingHelperInterface;
+use Shlinkio\Shlink\Core\Options\RobotsOptions;
 
 use function sprintf;
 
@@ -17,7 +18,7 @@ use const PHP_EOL;
 
 readonly class RobotsAction implements RequestHandlerInterface, StatusCodeInterface
 {
-    public function __construct(private CrawlingHelperInterface $crawlingHelper, private bool $allowAllShortUrls)
+    public function __construct(private CrawlingHelperInterface $crawlingHelper, private RobotsOptions $robotsOptions)
     {
     }
 
@@ -33,11 +34,15 @@ readonly class RobotsAction implements RequestHandlerInterface, StatusCodeInterf
         # For more information about the robots.txt standard, see:
         # https://www.robotstxt.org/orig.html
 
-        User-agent: *
 
         ROBOTS;
 
-        if ($this->allowAllShortUrls) {
+        $userAgents = $this->robotsOptions->hasUserAgents() ? $this->robotsOptions->userAgents : ['*'];
+        foreach ($userAgents as $userAgent) {
+            yield sprintf('User-agent: %s%s', $userAgent, PHP_EOL);
+        }
+
+        if ($this->robotsOptions->allowAllShortUrls) {
             // Disallow rest URLs, but allow all short codes
             yield 'Disallow: /rest/';
             return;

module/Core/src/Config/EnvVars.php

@@ -71,6 +71,7 @@ enum EnvVars: string
     case REDIRECT_APPEND_EXTRA_PATH = 'REDIRECT_APPEND_EXTRA_PATH';
     case MULTI_SEGMENT_SLUGS_ENABLED = 'MULTI_SEGMENT_SLUGS_ENABLED';
     case ROBOTS_ALLOW_ALL_SHORT_URLS = 'ROBOTS_ALLOW_ALL_SHORT_URLS';
+    case ROBOTS_USER_AGENTS = 'ROBOTS_USER_AGENTS';
     case TIMEZONE = 'TIMEZONE';
     case MEMORY_LIMIT = 'MEMORY_LIMIT';
 

module/Core/src/Options/RobotsOptions.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shlinkio\Shlink\Core\Options;
+
+use function count;
+
+final readonly class RobotsOptions
+{
+    public function __construct(
+        public bool $allowAllShortUrls = false,
+        /** @var string[] */
+        public array $userAgents = [],
+    ) {
+    }
+
+    public function hasUserAgents(): bool
+    {
+        return count($this->userAgents) > 0;
+    }
+}

module/Core/test/Action/RobotsActionTest.php

@@ -11,6 +11,7 @@ use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
 use Shlinkio\Shlink\Core\Action\RobotsAction;
 use Shlinkio\Shlink\Core\Crawling\CrawlingHelperInterface;
+use Shlinkio\Shlink\Core\Options\RobotsOptions;
 
 class RobotsActionTest extends TestCase
 {
@@ -24,15 +25,15 @@ class RobotsActionTest extends TestCase
     #[Test, DataProvider('provideShortCodes')]
     public function buildsRobotsLinesFromCrawlableShortCodes(
         array $shortCodes,
-        bool $allowAllShortUrls,
+        RobotsOptions $options,
         string $expected,
     ): void {
         $this->helper
-            ->expects($allowAllShortUrls ? $this->never() : $this->once())
+            ->expects($options->allowAllShortUrls ? $this->never() : $this->once())
             ->method('listCrawlableShortCodes')
             ->willReturn($shortCodes);
 
-        $response = $this->action($allowAllShortUrls)->handle(ServerRequestFactory::fromGlobals());
+        $response = $this->action($options)->handle(ServerRequestFactory::fromGlobals());
 
         self::assertEquals(200, $response->getStatusCode());
         self::assertEquals($expected, $response->getBody()->__toString());
@@ -41,7 +42,7 @@ class RobotsActionTest extends TestCase
 
     public static function provideShortCodes(): iterable
     {
-        yield 'three short codes' => [['foo', 'bar', 'baz'], false, <<<ROBOTS
+        yield 'three short codes' => [['foo', 'bar', 'baz'], new RobotsOptions(), <<<ROBOTS
         # For more information about the robots.txt standard, see:
         # https://www.robotstxt.org/orig.html
 
@@ -51,7 +52,7 @@ class RobotsActionTest extends TestCase
         Allow: /baz
         Disallow: /
         ROBOTS];
-        yield 'five short codes' => [['foo', 'bar', 'some', 'thing', 'baz'], false, <<<ROBOTS
+        yield 'five short codes' => [['foo', 'bar', 'some', 'thing', 'baz'], new RobotsOptions(), <<<ROBOTS
         # For more information about the robots.txt standard, see:
         # https://www.robotstxt.org/orig.html
 
@@ -63,31 +64,43 @@ class RobotsActionTest extends TestCase
         Allow: /baz
         Disallow: /
         ROBOTS];
-        yield 'no short codes' => [[], false, <<<ROBOTS
+        yield 'no short codes' => [[], new RobotsOptions(), <<<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
+        yield 'three short codes and allow all short urls' => [
+            ['foo', 'bar', 'some'],
+            new RobotsOptions(allowAllShortUrls: 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' => [[], new RobotsOptions(allowAllShortUrls: 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
+        yield 'allow user agents' => [[], new RobotsOptions(userAgents: ['foo', 'bar']), <<<ROBOTS
         # For more information about the robots.txt standard, see:
         # https://www.robotstxt.org/orig.html
 
-        User-agent: *
-        Disallow: /rest/
+        User-agent: foo
+        User-agent: bar
+        Disallow: /
         ROBOTS];
     }
 
-    private function action(bool $allowAllShortUrls = false): RobotsAction
+    private function action(RobotsOptions $options): RobotsAction
     {
-        return new RobotsAction($this->helper, allowAllShortUrls: $allowAllShortUrls);
+        return new RobotsAction($this->helper, $options);
     }
 }