Issue #3173988: Azure/AWS: Take into account CONFIG command may not work

src/Controller/ReportController.php

@@ -4,9 +4,11 @@ namespace Drupal\redis\Controller;
 
 use Drupal\Core\Controller\ControllerBase;
 use Drupal\Core\Datetime\DateFormatterInterface;
+use Drupal\Core\Logger\RfcLogLevel;
 use Drupal\Core\Url;
 use Drupal\redis\ClientFactory;
 use Drupal\redis\RedisPrefixTrait;
+use Exception;
 use Predis\Collection\Iterator\Keyspace;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
@@ -167,21 +169,38 @@ class ReportController extends ControllerBase {
     }
 
     $end = microtime(TRUE);
-    $memory_config = $this->redis->config('get', 'maxmemory*');
-
-    if ($memory_config['maxmemory']) {
-      $memory_value = $this->t('@used_memory / @max_memory (@used_percentage%), maxmemory policy: @policy', [
-        '@used_memory' => $info['used_memory_human'] ?? $info['Memory']['used_memory_human'],
-        '@max_memory' => format_size($memory_config['maxmemory']),
-        '@used_percentage' => (int) ($info['used_memory'] ?? $info['Memory']['used_memory'] / $memory_config['maxmemory'] * 100),
-        '@policy' => $memory_config['maxmemory-policy'],
-      ]);
+
+    // Various Redis providers may have actually disabled the CONFIG command, so
+    // try this, but don't be surprised if it fails.
+    try {
+      $memory_config = $this->redis->config('get', 'maxmemory*');
+
+      if ($memory_config['maxmemory']) {
+        $memory_value = $this->t('@used_memory / @max_memory (@used_percentage%), maxmemory policy: @policy', [
+          '@used_memory' => $info['used_memory_human'] ?? $info['Memory']['used_memory_human'],
+          '@max_memory' => format_size($memory_config['maxmemory']),
+          '@used_percentage' => (int) ($info['used_memory'] ?? $info['Memory']['used_memory'] / $memory_config['maxmemory'] * 100),
+          '@policy' => $memory_config['maxmemory-policy'],
+        ]);
+      }
+      else {
+        $memory_value = $this->t('@used_memory / unlimited, maxmemory policy: @policy', [
+          '@used_memory' => $info['used_memory_human'] ?? $info['Memory']['used_memory_human'],
+          '@policy' => $memory_config['maxmemory-policy'],
+        ]);
+      }
     }
-    else {
-      $memory_value = $this->t('@used_memory / unlimited, maxmemory policy: @policy', [
-        '@used_memory' => $info['used_memory_human'] ?? $info['Memory']['used_memory_human'],
-        '@policy' => $memory_config['maxmemory-policy'],
-      ]);
+    // We can't be sure what sort of Exception will be thrown, depends on the
+    // integration used.
+    catch (Exception $e) {
+      $memory_value = $info['used_memory_human'] ?? $info['Memory']['used_memory_human'];
+
+      watchdog_exception(
+        'redis',
+        $e,
+        'Exception caught while trying to retrieve memory configuration from Redis. This may just be a security measure from your Redis provider. %type: @message in %function (line %line of %file).',
+        [],
+        RfcLogLevel::INFO);
     }
 
     $requirements = [
@@ -248,7 +267,7 @@ class ReportController extends ControllerBase {
     ];
 
     // Warnings/hints.
-    if ($memory_config['maxmemory-policy'] == 'noeviction') {
+    if (isset($memory_config['maxmemory-policy']) && $memory_config['maxmemory-policy'] == 'noeviction') {
       $redis_url = Url::fromUri('https://redis.io/topics/lru-cache', [
         'fragment' => 'eviction-policies',
         'attributes' => [