Add API endpoint to get a server by external ID

app/Http/Controllers/Api/Application/Servers/ExternalServerController.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace Pterodactyl\Http\Controllers\Api\Application\Servers;
+
+use Pterodactyl\Transformers\Api\Application\ServerTransformer;
+use Pterodactyl\Http\Controllers\Api\Application\ApplicationApiController;
+use Pterodactyl\Http\Requests\Api\Application\Servers\GetExternalServerRequest;
+
+class ExternalServerController extends ApplicationApiController
+{
+    /**
+     * Retrieve a specific server from the database using its external ID.
+     *
+     * @param \Pterodactyl\Http\Requests\Api\Application\Servers\GetExternalServerRequest $request
+     * @return array
+     */
+    public function index(GetExternalServerRequest $request): array
+    {
+        return $this->fractal->item($request->getServerModel())
+            ->transformWith($this->getTransformer(ServerTransformer::class))
+            ->toArray();
+    }
+}

app/Http/Requests/Api/Application/Servers/GetExternalServerRequest.php

@@ -0,0 +1,57 @@
+<?php
+
+namespace Pterodactyl\Http\Requests\Api\Application\Servers;
+
+use Pterodactyl\Models\Server;
+use Pterodactyl\Services\Acl\Api\AdminAcl;
+use Pterodactyl\Exceptions\Repository\RecordNotFoundException;
+use Pterodactyl\Contracts\Repository\ServerRepositoryInterface;
+use Pterodactyl\Http\Requests\Api\Application\ApplicationApiRequest;
+
+class GetExternalServerRequest extends ApplicationApiRequest
+{
+    /**
+     * @var \Pterodactyl\Models\Server
+     */
+    private $serverModel;
+
+    /**
+     * @var string
+     */
+    protected $resource = AdminAcl::RESOURCE_SERVERS;
+
+    /**
+     * @var int
+     */
+    protected $permission = AdminAcl::READ;
+
+    /**
+     * Determine if the requested external user exists.
+     *
+     * @return bool
+     */
+    public function resourceExists(): bool
+    {
+        $repository = $this->container->make(ServerRepositoryInterface::class);
+
+        try {
+            $this->serverModel = $repository->findFirstWhere([
+                ['external_id', '=', $this->route()->parameter('external_id')],
+            ]);
+        } catch (RecordNotFoundException $exception) {
+            return false;
+        }
+
+        return true;
+    }
+
+    /**
+     * Return the server model for the requested external server.
+     *
+     * @return \Pterodactyl\Models\Server
+     */
+    public function getServerModel(): Server
+    {
+        return $this->serverModel;
+    }
+}