Add command "app:config:status" to check if "app:config:import" needed

app/code/Magento/Deploy/Console/Command/App/ConfigStatusCommand.php

@@ -0,0 +1,64 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Magento\Deploy\Console\Command\App;
+
+use Magento\Deploy\Model\DeploymentConfig\ChangeDetector;
+use Magento\Framework\Console\Cli;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+/**
+ * Command for checking if Config propagation is up to date
+ */
+class ConfigStatusCommand extends Command
+{
+    /**
+     * Code for error when config import is required.
+     */
+    const EXIT_CODE_CONFIG_IMPORT_REQUIRED = 2;
+
+    /**
+     * @var ChangeDetector
+     */
+    private $changeDetector;
+
+    /**
+     * ConfigStatusCommand constructor.
+     * @param ChangeDetector $changeDetector
+     */
+    public function __construct(ChangeDetector $changeDetector)
+    {
+        $this->changeDetector = $changeDetector;
+        parent::__construct();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function configure()
+    {
+        $this->setName('app:config:status')
+            ->setDescription('Checks if config propagation requires update');
+        parent::configure();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function execute(InputInterface $input, OutputInterface $output)
+    {
+        if ($this->changeDetector->hasChanges()) {
+            $output->writeln(
+                '<info>Config files have changed. ' .
+                'Run app:config:import or setup:upgrade command to synchronize configuration.</info>'
+            );
+            return self::EXIT_CODE_CONFIG_IMPORT_REQUIRED;
+        }
+        $output->writeln('<info>Config files are up to date.</info>');
+        return Cli::RETURN_SUCCESS;
+    }
+}

app/code/Magento/Deploy/Test/Unit/Console/Command/App/ConfigStatusCommandTest.php

@@ -0,0 +1,76 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Magento\Deploy\Test\Unit\Console\Command\App;
+
+use Magento\Deploy\Console\Command\App\ConfigStatusCommand;
+use Magento\Deploy\Model\DeploymentConfig\ChangeDetector;
+use Magento\Framework\Console\Cli;
+use Symfony\Component\Console\Tester\CommandTester;
+
+/**
+ * @inheritdoc
+ */
+class ConfigStatusCommandTest extends \PHPUnit\Framework\TestCase
+{
+
+    /**
+     * @var ConfigStatusCommand
+     */
+    private $command;
+    /**
+     * @var ChangeDetector
+     */
+    private $changeDetector;
+
+    /**
+     * @inheritdoc
+     */
+    protected function setUp()
+    {
+        $this->changeDetector = $this->getMockBuilder(ChangeDetector::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+
+        $this->command = new ConfigStatusCommand($this->changeDetector);
+    }
+
+    /**
+     * @param bool $hasChanges
+     * @param string $expectedMessage
+     * @param int $expectedCode
+     *
+     * @dataProvider executeDataProvider
+     */
+    public function testExecute(bool $hasChanges, $expectedMessage, $expectedCode)
+    {
+        $this->changeDetector->expects($this->once())
+            ->method('hasChanges')
+            ->will($this->returnValue($hasChanges));
+
+        $tester = new CommandTester($this->command);
+        $tester->execute([]);
+
+        $this->assertEquals($expectedMessage, $tester->getDisplay());
+        $this->assertSame($expectedCode, $tester->getStatusCode());
+    }
+
+    public function executeDataProvider()
+    {
+        return [
+            'Config is up to date' => [
+                false,
+                'Config files are up to date.' . PHP_EOL,
+                Cli::RETURN_SUCCESS
+            ],
+            'Config needs update' => [
+                true,
+                'Config files have changed. ' .
+                'Run app:config:import or setup:upgrade command to synchronize configuration.' . PHP_EOL,
+                ConfigStatusCommand::EXIT_CODE_CONFIG_IMPORT_REQUIRED,
+            ],
+        ];
+    }
+}

app/code/Magento/Deploy/etc/di.xml

@@ -31,6 +31,7 @@
                 <item name="dumpApplicationCommand" xsi:type="object">\Magento\Deploy\Console\Command\App\ApplicationDumpCommand</item>
                 <item name="sensitiveConfigSetCommand" xsi:type="object">\Magento\Deploy\Console\Command\App\SensitiveConfigSetCommand</item>
                 <item name="configImportCommand" xsi:type="object">Magento\Deploy\Console\Command\App\ConfigImportCommand</item>
+                <item name="configStatusCommand" xsi:type="object">Magento\Deploy\Console\Command\App\ConfigStatusCommand</item>
             </argument>
         </arguments>
     </type>