diff --git a/.config/redis.config.php b/.config/redis.config.php
index a5b13da6..2069812f 100644
--- a/.config/redis.config.php
+++ b/.config/redis.config.php
@@ -14,4 +14,8 @@ if (getenv('REDIS_HOST')) {
   } elseif (getenv('REDIS_HOST')[0] != '/') {
     $CONFIG['redis']['port'] = 6379;
   }
+
+  if (getenv('REDIS_HOST_USER') !== false) {
+    $CONFIG['redis']['user'] = (string) getenv('REDIS_HOST_USER');
+  }
 }
diff --git a/28/fpm-alpine/Dockerfile b/28/fpm-alpine/Dockerfile
index 02cd4a23..63569f89 100644
--- a/28/fpm-alpine/Dockerfile
+++ b/28/fpm-alpine/Dockerfile
@@ -1,5 +1,5 @@
 # DO NOT EDIT: created by update.sh from Dockerfile-alpine.template
-FROM php:8.2-fpm-alpine3.20
+FROM php:8.2-fpm-alpine3.21
 
 # entrypoint.sh and cron.sh dependencies
 RUN set -ex; \
diff --git a/29/fpm-alpine/Dockerfile b/29/fpm-alpine/Dockerfile
index 4e147a5c..6e4ea4d1 100644
--- a/29/fpm-alpine/Dockerfile
+++ b/29/fpm-alpine/Dockerfile
@@ -1,5 +1,5 @@
 # DO NOT EDIT: created by update.sh from Dockerfile-alpine.template
-FROM php:8.2-fpm-alpine3.20
+FROM php:8.2-fpm-alpine3.21
 
 # entrypoint.sh and cron.sh dependencies
 RUN set -ex; \
diff --git a/30/fpm-alpine/Dockerfile b/30/fpm-alpine/Dockerfile
index 52ea716c..9bd77015 100644
--- a/30/fpm-alpine/Dockerfile
+++ b/30/fpm-alpine/Dockerfile
@@ -1,5 +1,5 @@
 # DO NOT EDIT: created by update.sh from Dockerfile-alpine.template
-FROM php:8.2-fpm-alpine3.20
+FROM php:8.2-fpm-alpine3.21
 
 # entrypoint.sh and cron.sh dependencies
 RUN set -ex; \
diff --git a/README.md b/README.md
index 6745faa3..6fdd5ec9 100644
--- a/README.md
+++ b/README.md
@@ -236,6 +236,7 @@ To use Redis for memory caching as well as PHP session storage, specify the foll
 
 - `REDIS_HOST` (not set by default) Name of Redis container
 - `REDIS_HOST_PORT` (default: `6379`) Optional port for Redis, only use for external Redis servers that run on non-standard ports.
+- `REDIS_HOST_USER` (not set by default) Optional username for Redis, only use for external Redis servers that require a user.
 - `REDIS_HOST_PASSWORD` (not set by default) Redis password
 
 Check the [Nextcloud documentation](https://docs.nextcloud.com/server/latest/admin_manual/configuration_server/caching_configuration.html) for more information.
diff --git a/update.sh b/update.sh
index 6e576238..89f3d6f2 100755
--- a/update.sh
+++ b/update.sh
@@ -2,7 +2,7 @@
 set -eo pipefail
 
 declare -A alpine_version=(
-	[default]='3.20'
+	[default]='3.21'
 )
 
 declare -A debian_version=(
diff --git a/versions.json b/versions.json
index ec8b3ca9..09f25557 100644
--- a/versions.json
+++ b/versions.json
@@ -20,7 +20,7 @@
       "fpm-alpine": {
         "variant": "fpm-alpine",
         "base": "alpine",
-        "baseVersion": "3.20",
+        "baseVersion": "3.21",
         "phpVersion": "8.2"
       }
     }
@@ -46,7 +46,7 @@
       "fpm-alpine": {
         "variant": "fpm-alpine",
         "base": "alpine",
-        "baseVersion": "3.20",
+        "baseVersion": "3.21",
         "phpVersion": "8.2"
       }
     }
@@ -72,7 +72,7 @@
       "fpm-alpine": {
         "variant": "fpm-alpine",
         "base": "alpine",
-        "baseVersion": "3.20",
+        "baseVersion": "3.21",
         "phpVersion": "8.2"
       }
     }