How do you use RedisSessionHandler in Symfony 4? Broken docs - php

Question

The documentation is broken and leads to a 404 page. I'm not too good at reverse engineering classes like this, any tips on how to setup services.yml to use it?
Doc page
https://symfony.com/doc/current/components/http_foundation/session_configuration.html
Session Handler 404
https://api.symfony.com/4.1/Symfony/Component/HttpFoundation/Session/Storage/Handler/RedisSessionHandler.html
Git Page for Session Handler
https://github.com/symfony/symfony/blob/master/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/RedisSessionHandler.php

Answer 1

You need to define 2 services:
One for the Redis connection.
One for RedisSessionHandler that will make use of that connection.
Edit the services file:
# config/services.yaml
services:
Redis:
class: Redis
calls:
- method: connect
arguments:
- '%env(REDIS_HOST)%'
- '%env(int:REDIS_PORT)%'
# If you need key prefix
# - method: setOption
# arguments:
# - !php/const Redis::OPT_PREFIX
# - 'my_prefix'
Symfony\Component\HttpFoundation\Session\Storage\Handler\RedisSessionHandler:
arguments:
- '#Redis'
(note that I stored here the Redis host & port as environment variables, but you can define them elsewhere if needed).
You can now make use of the service as your session handler:
# config/packages/framework.yaml
framework:
session:
handler_id: Symfony\Component\HttpFoundation\Session\Storage\Handler\RedisSessionHandler
I struggled a bit too, and wrote a more detailed articled: http://blog.michaelperrin.fr/2018/08/14/redis-session-handling-in-symfony/

Answer 2

For adding custom prefix, maybe the following is better:
Redis:
class: Redis
calls:
- method: connect
arguments:
- '%env(REDIS_HOST)%'
- '%env(int:REDIS_PORT)%'
# - method: setOption
# arguments:
# # #see https://symfony.com/blog/new-in-symfony-3-2-php-constants-in-yaml-files
# - !php/const Redis::OPT_PREFIX
Symfony\Component\HttpFoundation\Session\Storage\Handler\RedisSessionHandler:
arguments:
- '#Redis'
# #see https://symfony.com/doc/current/components/yaml/yaml_format.html
-
prefix: ivannotes_