feat(config): add serverid configuration and use it for Snowflakes

Signed-off-by: Benjamin Gaussorgues <benjamin.gaussorgues@nextcloud.com>

apps/settings/composer/composer/autoload_classmap.php

@@ -132,6 +132,7 @@ return array(
     'OCA\\Settings\\SetupChecks\\ReadOnlyConfig' => $baseDir . '/../lib/SetupChecks/ReadOnlyConfig.php',
     'OCA\\Settings\\SetupChecks\\SchedulingTableSize' => $baseDir . '/../lib/SetupChecks/SchedulingTableSize.php',
     'OCA\\Settings\\SetupChecks\\SecurityHeaders' => $baseDir . '/../lib/SetupChecks/SecurityHeaders.php',
+    'OCA\\Settings\\SetupChecks\\ServerIdConfig' => $baseDir . '/../lib/SetupChecks/ServerIdConfig.php',
     'OCA\\Settings\\SetupChecks\\SupportedDatabase' => $baseDir . '/../lib/SetupChecks/SupportedDatabase.php',
     'OCA\\Settings\\SetupChecks\\SystemIs64bit' => $baseDir . '/../lib/SetupChecks/SystemIs64bit.php',
     'OCA\\Settings\\SetupChecks\\TaskProcessingPickupSpeed' => $baseDir . '/../lib/SetupChecks/TaskProcessingPickupSpeed.php',

apps/settings/composer/composer/autoload_static.php

@@ -147,6 +147,7 @@ class ComposerStaticInitSettings
         'OCA\\Settings\\SetupChecks\\ReadOnlyConfig' => __DIR__ . '/..' . '/../lib/SetupChecks/ReadOnlyConfig.php',
         'OCA\\Settings\\SetupChecks\\SchedulingTableSize' => __DIR__ . '/..' . '/../lib/SetupChecks/SchedulingTableSize.php',
         'OCA\\Settings\\SetupChecks\\SecurityHeaders' => __DIR__ . '/..' . '/../lib/SetupChecks/SecurityHeaders.php',
+        'OCA\\Settings\\SetupChecks\\ServerIdConfig' => __DIR__ . '/..' . '/../lib/SetupChecks/ServerIdConfig.php',
         'OCA\\Settings\\SetupChecks\\SupportedDatabase' => __DIR__ . '/..' . '/../lib/SetupChecks/SupportedDatabase.php',
         'OCA\\Settings\\SetupChecks\\SystemIs64bit' => __DIR__ . '/..' . '/../lib/SetupChecks/SystemIs64bit.php',
         'OCA\\Settings\\SetupChecks\\TaskProcessingPickupSpeed' => __DIR__ . '/..' . '/../lib/SetupChecks/TaskProcessingPickupSpeed.php',

apps/settings/lib/AppInfo/Application.php

@@ -69,6 +69,7 @@ use OCA\Settings\SetupChecks\RandomnessSecure;
 use OCA\Settings\SetupChecks\ReadOnlyConfig;
 use OCA\Settings\SetupChecks\SchedulingTableSize;
 use OCA\Settings\SetupChecks\SecurityHeaders;
+use OCA\Settings\SetupChecks\ServerIdConfig;
 use OCA\Settings\SetupChecks\SupportedDatabase;
 use OCA\Settings\SetupChecks\SystemIs64bit;
 use OCA\Settings\SetupChecks\TaskProcessingPickupSpeed;
@@ -207,6 +208,7 @@ class Application extends App implements IBootstrap {
 		$context->registerSetupCheck(RandomnessSecure::class);
 		$context->registerSetupCheck(ReadOnlyConfig::class);
 		$context->registerSetupCheck(SecurityHeaders::class);
+		$context->registerSetupCheck(ServerIdConfig::class);
 		$context->registerSetupCheck(SchedulingTableSize::class);
 		$context->registerSetupCheck(SupportedDatabase::class);
 		$context->registerSetupCheck(SystemIs64bit::class);

apps/settings/lib/SetupChecks/ServerIdConfig.php

@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2025 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OCA\Settings\SetupChecks;
+
+use OCP\IConfig;
+use OCP\IL10N;
+use OCP\IURLGenerator;
+use OCP\SetupCheck\ISetupCheck;
+use OCP\SetupCheck\SetupResult;
+use Override;
+
+final class ServerIdConfig implements ISetupCheck {
+	public function __construct(
+		private readonly IL10N $l10n,
+		private readonly IConfig $config,
+		private readonly IURLGenerator $urlGenerator,
+	) {
+	}
+
+	#[Override]
+	public function getName(): string {
+		return $this->l10n->t('Configuration server ID');
+	}
+
+	#[Override]
+	public function getCategory(): string {
+		return 'config';
+	}
+
+	#[Override]
+	public function run(): SetupResult {
+		$serverid = $this->config->getSystemValueInt('serverid', PHP_INT_MIN);
+		$linkToDoc = $this->urlGenerator->linkToDocs('admin-update');
+
+		if ($serverid === PHP_INT_MIN) {
+			return SetupResult::info(
+				$this->l10n->t('server identifier isn’t configured. It is recommended if your Nextcloud instance is running on several PHP servers. Add a serverid in your configuration.'),
+				$linkToDoc,
+			);
+		}
+
+		if ($serverid < 0 || $serverid > 1023) {
+			return SetupResult::error(
+				$this->l10n->t('"%d" is not a valid server identifier. It must be between 0 and 1023.', [$serverid]),
+				$linkToDoc,
+			);
+		}
+
+		return SetupResult::success($this->l10n->t('server identifier is configured and valid.'));
+	}
+}

config/config.sample.php

@@ -45,6 +45,20 @@ $CONFIG = [
 	 */
 	'instanceid' => '',
 
+	/**
+	 * This is a unique identifier for your server.
+	 * It is useful when your Nextcloud instance is using different PHP servers.
+	 * Once it's set it shouldn't be changed.
+	 *
+	 * Value must be an integer, comprised between 0 and 1023.
+	 *
+	 * When config.php is shared between different servers, this value should be overriden with "NC_serverid=<int>" on each server.
+	 * Note that it must be overriden for CLI and for your webserver.
+	 *
+	 * Example for CLI: NC_serverid=42 occ config:list system
+	 */
+	'serverid' => -1,
+
 	/**
 	 * The salt used to hash all passwords, auto-generated by the Nextcloud
 	 * installer. (There are also per-user salts.) If you lose this salt, you lose

lib/private/Snowflake/Generator.php

@@ -10,6 +10,7 @@ declare(strict_types=1);
 namespace OC\Snowflake;
 
 use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\IConfig;
 use OCP\Snowflake\IGenerator;
 use Override;
 
@@ -23,6 +24,7 @@ use Override;
 final class Generator implements IGenerator {
 	public function __construct(
 		private readonly ITimeFactory $timeFactory,
+		private readonly IConfig $config,
 		private readonly ISequence $sequenceGenerator,
 	) {
 	}
@@ -100,8 +102,14 @@ final class Generator implements IGenerator {
 		];
 	}
 
+	/**
+	 * Return configured serverid or generate one if not set
+	 */
 	private function getServerId(): int {
-		return crc32(gethostname() ?: random_bytes(8));
+		$serverid = $this->config->getSystemValueInt('serverid', -1);
+		return $serverid > 0
+			? $serverid
+			: crc32(gethostname() ?: random_bytes(8));
 	}
 
 	private function isCli(): bool {

tests/lib/Snowflake/GeneratorTest.php

@@ -14,6 +14,7 @@ use OC\Snowflake\Decoder;
 use OC\Snowflake\Generator;
 use OC\Snowflake\ISequence;
 use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\IConfig;
 use OCP\Snowflake\IGenerator;
 use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\MockObject\MockObject;
@@ -24,17 +25,25 @@ use Test\TestCase;
  */
 class GeneratorTest extends TestCase {
 	private Decoder $decoder;
+	private IConfig&MockObject $config;
 	private ISequence&MockObject $sequence;
 
 	public function setUp():void {
 		$this->decoder = new Decoder();
+
+		$this->config = $this->createMock(IConfig::class);
+		$this->config->method('getSystemValueInt')
+			->with('serverid')
+			->willReturn(42);
+
 		$this->sequence = $this->createMock(ISequence::class);
 		$this->sequence->method('isAvailable')->willReturn(true);
 		$this->sequence->method('nextId')->willReturn(421);
+
 	}
 
 	public function testGenerator(): void {
-		$generator = new Generator(new TimeFactory(), $this->sequence);
+		$generator = new Generator(new TimeFactory(), $this->config, $this->sequence);
 		$snowflakeId = $generator->nextId();
 		$data = $this->decoder->decode($generator->nextId());
 
@@ -52,6 +61,9 @@ class GeneratorTest extends TestCase {
 
 		// Check CLI
 		$this->assertTrue($data['isCli']);
+
+		// Check serverId
+		$this->assertEquals(42, $data['serverId']);
 	}
 
 	#[DataProvider('provideSnowflakeData')]
@@ -60,11 +72,12 @@ class GeneratorTest extends TestCase {
 		$timeFactory = $this->createMock(ITimeFactory::class);
 		$timeFactory->method('now')->willReturn($dt);
 
-		$generator = new Generator($timeFactory, $this->sequence);
+		$generator = new Generator($timeFactory, $this->config, $this->sequence);
 		$data = $this->decoder->decode($generator->nextId());
 
 		$this->assertEquals($expectedSeconds, ($data['createdAt']->format('U') - IGenerator::TS_OFFSET));
 		$this->assertEquals($expectedMilliseconds, (int)$data['createdAt']->format('v'));
+		$this->assertEquals(42, $data['serverId']);
 	}
 
 	public static function provideSnowflakeData(): array {