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2024-10-18T06:44:45Z

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1>Aviation hacker: Quick mention of the Request cache up top as well.

2023-09-01T05:16:01Z

Quick mention of the Request cache up top as well.

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{{Performance}}
The Redis cache store is one of the best options to handle session and application cache as it supports: data guarantee, locking, key awareness. (and also can be used for [[Session_handling#Redis_session_driver|user's sessions caching]] in the config.php file). Unfortunately due to the data types it supports and the data involved, it isn't fully compatible with the request cache, and so we'll only be configuring it for the Application and Session caches in this document. That isn't to say you couldn't have parts of the request cache using Redis, you would just need to manually set those cached objects to use Redis instead (and there are quite a few of them!).

Before Redis is available as a cache store, you will need to install Redis service (daemon) on your Moodle server, locally in case of a single Moodle app node architecture or externally if you are using a cluster of Moodle nodes. only then, you can configure Redis as an application or session level cache store.

If you are configuring a cluster of Moodle servers/nodes, the Redis service (daemon) should be installed on an external server and all Moodle nodes (servers/instances) should point to that external Redis, so that all the user's cached data (namely Session) is available when the user is using/connected to any of the Moodle nodes. An external Redis (NoSQL) service can be installed on the main SQL server alongside the MySQL/MariaDB service, just make sure you have enough memory allocated on that server for both services.

A good practice is to give the Redis cache store prefix a proper short name and not leave it empty, as later on, it might conflict with user's session Redis cache you might choose to use, or other Moodle instances that will be installed on the same server. for example "my-school-name_cs_", where you replace "my-school-name" with your short school name. (and if you are also using a user's session store on the config.php file, you might like to prefix it with "my-school-name_us_")

When using a cluster setup with several Moodle instances on each node that belong to different Schools/Institutes/clients, make sure that you use the same Prefix for all Moodle instances that are on different nodes and are of the same School/Institute/Client.
==Installing Redis server==
There are plenty of guides on the internet on how to install Redis, so we won't repeat them here. Since Redis is a listening service, once it's installed it'll be ready to use (and should already be running) and ready to receive requests from Moodle, with no further configuration needed. With that said however, it's still wise to have a look through the configuration options and decide what is best for you and your setup - the DigitalOcean guide is a good place to start for adjusting these settings, as they're basically all in the redis.conf file.
* [https://www.digitalocean.com/community/tutorials/how-to-install-and-secure-redis-on-ubuntu-22-04 DigitalOcean's How To Install and Secure Redis on Ubuntu 22.04]
*[[Session_handling#Redis_session_driver]] and [https://www.digitalocean.com/community/tutorials/how-to-set-up-a-redis-server-as-a-session-handler-for-php-on-ubuntu-14-04 How to Set Up a Redis Server as a Session Handler for PHP]
* Install [https://dl.iuscommunity.org/pub/ius/stable/CentOS/7/x86_64/repoview/redis5.html Redis 5] via IUS CentOS 7 repository.
*[https://github.com/zkteco-home/redis-windows Redis Windows Port - zkteco-home/redis-windows on GitHub]
==Installing Redis php driver==
* For CentOS, you can use either [https://rpms.remirepo.net/ Remi] or [https://ius.io/ IUS] repositories, and install the [https://dl.iuscommunity.org/pub/ius/stable/CentOS/7/x86_64/repoview/php71u-pecl-redis.html php71u-pecl-redis] driver.
* [https://gist.github.com/hollodotme/418e9b7c6ebc358e7fda Redis php-fpm 7 driver on Ubuntu 14.04]
* [https://pecl.php.net/package/redis Windows PHP extensions] including DLLs for Windows. Check your PHP version, CPU (64bit or x86) and thread-safe value (see Site Admin > Server > PHP Info) to get the right version; add DLL file to ext directory, add 'extension=php_redis.dll' entry to php.ini and restart your web server.
==Configuring Redis in Moodle==
* Navigate to Site admin > Plugins > Caching > Configuration.
* When installed, you should see a green tick next to "Redis" under "Installed cache stores" and a link to add an instance.
[[File:Redis_cache_ready.png]]
* Click "Add instance".
** Give your Redis instance a name, like "Redis1" and set the IP:port for the Redis server. If it is on the same machine, the default would be 127.0.0.1:6379.
** The new instance should appear under "Configured store instances" with a "Ready" tick.
* Under "Stores used when no mapping is present" click '''Edit mappings". Set "Redis1" (or the name used earlier) for the "Application" and "Session" caches.''' Note that Redis won't appear under the "Request" Cache section, since it isn't fully compatible with all of the different parts of the request cache. (Refer to the [[Caching]] page to better understand how the Moodle Universal Cache works).
[[File:Set_Redis_as_default_Application_and_Session_cache.png]]
* After saving this, you should see Redis as the cache for most cache stores, and should hopefully see a performance boost almost immediately.
* Next Step: Celebrate!
==See also==
* [https://gist.github.com/kabel/10023961 Monitor Redis stats (a php one page app)]
* MDL-48468 : Add a Redis cache store to Moodle core
* Redis lock : https://github.com/open-lms-open-source/moodle-local_redislock (get it into core: https://tracker.moodle.org/browse/MDL-67022)
* [https://redis.io/ Redis.io]
[[de:Redis Cache]]

Redis cache store - История изменений

Олег Давидович: 1 версия импортирована

1>Aviation hacker: Quick mention of the Request cache up top as well.