Issue #3333215 by enchufe, arunkumark, mfb, Nitin shrivastava, smustgrave, cilefen: Return early if syslog configs are NULL to avoid openlog deprecation

core/modules/syslog/src/Logger/SysLog.php

@@ -52,8 +52,13 @@ class SysLog implements LoggerInterface {
    */
   protected function openConnection() {
     if (!$this->connectionOpened) {
+      // Do not connect if identity or facility are not configured.
+      $identity = $this->config->get('identity');
       $facility = $this->config->get('facility');
-      $this->connectionOpened = openlog($this->config->get('identity'), LOG_NDELAY, $facility);
+      if ($identity === NULL || $facility === NULL) {
+        return;
+      }
+      $this->connectionOpened = openlog($identity, LOG_NDELAY, $facility);
     }
   }
 
@@ -73,6 +78,9 @@ class SysLog implements LoggerInterface {
 
     // Ensure we have a connection available.
     $this->openConnection();
+    if (!$this->connectionOpened) {
+      return;
+    }
 
     // Populate the message placeholders and then replace them in the message.
     $message_placeholders = $this->parser->parseMessagePlaceholders($message, $context);

core/modules/syslog/tests/src/Kernel/SyslogTest.php

@@ -62,6 +62,20 @@ class SyslogTest extends KernelTestBase {
     $this->assertFileDoesNotExist($log_filename);
   }
 
+  /**
+   * Tests that missing facility prevents writing to the syslog.
+   *
+   * @covers ::openConnection
+   */
+  public function testSyslogMissingFacility() {
+    $config = $this->container->get('config.factory')->getEditable('syslog.settings');
+    $config->clear('facility');
+    $config->save();
+    \Drupal::logger('my_module')->warning('My warning message.');
+    $log_filename = $this->container->get('file_system')->realpath('public://syslog.log');
+    $this->assertFileDoesNotExist($log_filename);
+  }
+
   /**
    * Tests severity level logging.
    *