From 2385ae7ee2763b3106e426c2ca3b331ad3dfa378 Mon Sep 17 00:00:00 2001
From: Michael Aherne <michael.aherne@strath.ac.uk>
Date: Mon, 17 Jun 2019 12:24:39 +0100
Subject: [PATCH] MDL-65941 cache: Prevent cache config failure on redis
 problems.

---
 cache/stores/redis/lib.php | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/cache/stores/redis/lib.php b/cache/stores/redis/lib.php
index bde6b9ecc0a..9a6b0576651 100644
--- a/cache/stores/redis/lib.php
+++ b/cache/stores/redis/lib.php
@@ -182,22 +182,28 @@ class cachestore_redis extends cache_store implements cache_is_key_aware, cache_
             $server = $serverconf[0];
             $port = $serverconf[1];
         }
-        if ($redis->connect($server, $port)) {
-            if (!empty($password)) {
-                $redis->auth($password);
+
+        try {
+            if ($redis->connect($server, $port)) {
+                if (!empty($password)) {
+                    $redis->auth($password);
+                }
+                // If using compressor, serialisation will be done at cachestore level, not php-redis.
+                if ($this->compressor == self::COMPRESSOR_NONE) {
+                    $redis->setOption(Redis::OPT_SERIALIZER, $this->serializer);
+                }
+                if (!empty($prefix)) {
+                    $redis->setOption(Redis::OPT_PREFIX, $prefix);
+                }
+                // Database setting option...
+                $this->isready = $this->ping($redis);
+            } else {
+                $this->isready = false;
             }
-            // If using compressor, serialisation will be done at cachestore level, not php-redis.
-            if ($this->compressor == self::COMPRESSOR_NONE) {
-                $redis->setOption(Redis::OPT_SERIALIZER, $this->serializer);
-            }
-            if (!empty($prefix)) {
-                $redis->setOption(Redis::OPT_PREFIX, $prefix);
-            }
-            // Database setting option...
-            $this->isready = $this->ping($redis);
-        } else {
+        } catch (\RedisException $e) {
             $this->isready = false;
         }
+
         return $redis;
     }