PHP.GT

Redis session storage

RedisHandler stores session data in Redis-compatible storage.

This is useful when an application runs on more than one server, or when the server filesystem is temporary. Redis and Valkey are common choices for this kind of shared session storage.

[!IMPORTANT] RedisHandler requires the phpredis extension. The package suggests ext-redis, but Composer cannot install PHP extensions for us.

Basic configuration

use GT\Session\RedisHandler;
use GT\Session\Session;

$session = new Session(new RedisHandler(), [
	"name" => "GT",
	"save_path" => "redis://localhost:6379/0",
]);

The save path is a DSN. Session recognises DSN-style save paths and leaves them unchanged.

DSN examples

redis://localhost:6379
redis://:secret@localhost:6379/0
redis://default:secret@redis.internal:6379/2
rediss://default:secret@redis.internal:25061/0

The path part selects the Redis database. If no database is supplied, database 0 is used.

Authentication

If the DSN contains both a username and password, the handler passes both to Redis::auth().

redis://default:secret@redis.internal:6379/0

If the DSN contains only a password, the handler authenticates with just the password.

redis://:secret@redis.internal:6379/0

Query parameters

Supported query parameters are:

  • prefix
  • ttl
  • timeout
  • read_timeout
  • persistent
  • persistent_id
  • verify_peer
  • verify_peer_name

Example:

rediss://default:secret@example-redis.internal:25061/0?prefix=GT:&ttl=1440&timeout=1.5&read_timeout=2.5&persistent=1

Key prefix

By default, Redis keys are prefixed with the session name followed by a colon.

For a session named GT, the key for session ID abc123 is:

GT:abc123

Set the prefix query parameter to choose a different prefix:

redis://localhost:6379/0?prefix=app-session:

TTL

The ttl query parameter controls the Redis expiry time in seconds.

redis://localhost:6379/0?ttl=3600

If no TTL is supplied, the handler uses PHP’s session.gc_maxlifetime value.

When TTL is greater than zero, writes use setEx(). Otherwise, writes use set().

TLS

Use rediss:// or tls:// for TLS connections.

rediss://default:secret@redis.internal:25061/0

For local testing against a TLS endpoint with self-signed certificates, verification can be disabled:

rediss://default:secret@redis.internal:25061/0?verify_peer=0&verify_peer_name=0

Only disable verification when we understand the security trade-off.

WebEngine configuration

In WebEngine, the same handler can be configured in config.ini:

[session]
handler=GT\Session\RedisHandler
path=rediss://default:secret@example-redis.internal:25061/0?prefix=GT:&ttl=1440
name=GT
use_cookies=true

[!NOTE] WebEngine passes [session] path to this library as save_path. For Redis, that value should be the Redis DSN rather than a filesystem path.

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