#Redis

• Introduction
• Configuration
  • Clusters
  • Predis
  • phpredis
• Interacting With Redis
  • Transactions
  • Pipelining Commands
• Pub / Sub

#Introduction

Redis is an open source, advanced key-value store. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets, and sorted sets.

Before using Redis with Laravel, we encourage you to install and use the phpredis PHP extension via PECL. The extension is more complex to install compared to "user-land" PHP packages but may yield better performance for applications that make heavy use of Redis. If you are using Laravel Sail, this extension is already installed in your application's Docker container.

If you are unable to install the phpredis extension, you may install the predis/predis package via Composer. Predis is a Redis client written entirely in PHP and does not require any additional extensions:

composer require predis/predis

#Configuration

You may configure your application's Redis settings via the config/database.php configuration file. Within this file, you will see a redis array containing the Redis servers utilized by your application:

'redis' => [

    'client' => env('REDIS_CLIENT', 'phpredis'),

    'default' => [
        'host' => env('REDIS_HOST', '127.0.0.1'),
        'password' => env('REDIS_PASSWORD'),
        'port' => env('REDIS_PORT', 6379),
        'database' => env('REDIS_DB', 0),
    ],

    'cache' => [
        'host' => env('REDIS_HOST', '127.0.0.1'),
        'password' => env('REDIS_PASSWORD'),
        'port' => env('REDIS_PORT', 6379),
        'database' => env('REDIS_CACHE_DB', 1),
    ],

],

Each Redis server defined in your configuration file is required to have a name, host, and a port unless you define a single URL to represent the Redis connection:

'redis' => [

    'client' => env('REDIS_CLIENT', 'phpredis'),

    'default' => [
        'url' => 'tcp://127.0.0.1:6379?database=0',
    ],

    'cache' => [
        'url' => 'tls://user:password@127.0.0.1:6380?database=1',
    ],

],

#Configuring The Connection Scheme

By default, Redis clients will use the tcp scheme when connecting to your Redis servers; however, you may use TLS / SSL encryption by specifying a scheme configuration option in your Redis server's configuration array:

'redis' => [

    'client' => env('REDIS_CLIENT', 'phpredis'),

    'default' => [
        'scheme' => 'tls',
        'host' => env('REDIS_HOST', '127.0.0.1'),
        'password' => env('REDIS_PASSWORD'),
        'port' => env('REDIS_PORT', 6379),
        'database' => env('REDIS_DB', 0),
    ],

],

#Clusters

If your application is utilizing a cluster of Redis servers, you should define these clusters within a clusters key of your Redis configuration. This configuration key does not exist by default so you will need to create it within your application's config/database.php configuration file:

'redis' => [

    'client' => env('REDIS_CLIENT', 'phpredis'),

    'clusters' => [
        'default' => [
            [
                'host' => env('REDIS_HOST', 'localhost'),
                'password' => env('REDIS_PASSWORD'),
                'port' => env('REDIS_PORT', 6379),
                'database' => 0,
            ],
        ],
    ],

],

By default, clusters will perform client-side sharding across your nodes, allowing you to pool nodes and create a large amount of available RAM. However, client-side sharding does not handle failover; therefore, it is primarily suited for transient cached data that is available from another primary data store.

If you would like to use native Redis clustering instead of client-side sharding, you may specify this by setting the options.cluster configuration value to redis within your application's config/database.php configuration file:

'redis' => [

    'client' => env('REDIS_CLIENT', 'phpredis'),

    'options' => [
        'cluster' => env('REDIS_CLUSTER', 'redis'),
    ],

    'clusters' => [
        // ...
    ],

],

#Predis

If you would like your application to interact with Redis via the Predis package, you should ensure the REDIS_CLIENT environment variable's value is predis:

'redis' => [

    'client' => env('REDIS_CLIENT', 'predis'),

    // ...
],

In addition to the default host, port, database, and password server configuration options, Predis supports additional connection parameters that may be defined for each of your Redis servers. To utilize these additional configuration options, add them to your Redis server configuration in your application's config/database.php configuration file:

'default' => [
    'host' => env('REDIS_HOST', 'localhost'),
    'password' => env('REDIS_PASSWORD'),
    'port' => env('REDIS_PORT', 6379),
    'database' => 0,
    'read_write_timeout' => 60,
],

#The Redis Facade Alias

Laravel's config/app.php configuration file contains an aliases array which defines all of the class aliases that will be registered by the framework. By default, no Redis alias is included because it would conflict with the Redis class name provided by the phpredis extension. If you are using the Predis client and would like to add a Redis alias, you may add it to the aliases array in your application's config/app.php configuration file:

'aliases' => Facade::defaultAliases()->merge([
    'Redis' => Illuminate\Support\Facades\Redis::class,
])->toArray(),

#phpredis

By default, Laravel will use the phpredis extension to communicate with Redis. The client that Laravel will use to communicate with Redis is dictated by the value of the redis.client configuration option, which typically reflects the value of the REDIS_CLIENT environment variable:

'redis' => [

    'client' => env('REDIS_CLIENT', 'phpredis'),

    // Rest of Redis configuration...
],

In addition to the default scheme, host, port, database, and password server configuration options, phpredis supports the following additional connection parameters: name, persistent, persistent_id, prefix, read_timeout, retry_interval, timeout, and context. You may add any of these options to your Redis server configuration in the config/database.php configuration file:

'default' => [
    'host' => env('REDIS_HOST', 'localhost'),
    'password' => env('REDIS_PASSWORD'),
    'port' => env('REDIS_PORT', 6379),
    'database' => 0,
    'read_timeout' => 60,
    'context' => [
        // 'auth' => ['username', 'secret'],
        // 'stream' => ['verify_peer' => false],
    ],
],

#phpredis Serialization & Compression

The phpredis extension may also be configured to use a variety of serialization and compression algorithms. These algorithms can be configured via the options array of your Redis configuration:

'redis' => [

    'client' => env('REDIS_CLIENT', 'phpredis'),

    'options' => [
        'serializer' => Redis::SERIALIZER_MSGPACK,
        'compression' => Redis::COMPRESSION_LZ4,
    ],

    // Rest of Redis configuration...
],

Currently supported serialization algorithms include: Redis::SERIALIZER_NONE (default), Redis::SERIALIZER_PHP, Redis::SERIALIZER_JSON, Redis::SERIALIZER_IGBINARY, and Redis::SERIALIZER_MSGPACK.

Supported compression algorithms include: Redis::COMPRESSION_NONE (default), Redis::COMPRESSION_LZF, Redis::COMPRESSION_ZSTD, and Redis::COMPRESSION_LZ4.

#Interacting With Redis

You may interact with Redis by calling various methods on the Redis facade. The Redis facade supports dynamic methods, meaning you may call any Redis command on the facade and the command will be passed directly to Redis. In this example, we will call the Redis GET command by calling the get method on the Redis facade:

<?php

namespace App\Http\Controllers;

use App\Http\Controllers\Controller;
use Illuminate\Support\Facades\Redis;
use Illuminate\View\View;

class UserController extends Controller
{
    /**
     * Show the profile for the given user.
     */
    public function show(string $id): View
    {
        return view('user.profile', [
            'user' => Redis::get('user:profile:'.$id)
        ]);
    }
}

As mentioned above, you may call any of Redis' commands on the Redis facade. Laravel uses magic methods to pass the commands to the Redis server. If a Redis command expects arguments, you should pass those to the facade's corresponding method:

use Illuminate\Support\Facades\Redis;

Redis::set('name', 'Taylor');

$values = Redis::lrange('names', 5, 10);

Alternatively, you may pass commands to the server using the Redis facade's command method, which accepts the name of the command as its first argument and an array of values as its second argument:

$values = Redis::command('lrange', ['name', 5, 10]);

#Using Multiple Redis Connections

Your application's config/database.php configuration file allows you to define multiple Redis connections / servers. You may obtain a connection to a specific Redis connection using the Redis facade's connection method:

$redis = Redis::connection('connection-name');

To obtain an instance of the default Redis connection, you may call the connection method without any additional arguments:

$redis = Redis::connection();

#Transactions

The Redis facade's transaction method provides a convenient wrapper around Redis' native MULTI and EXEC commands. The transaction method accepts a closure as its only argument. This closure will receive a Redis connection instance and may issue any commands it would like to this instance. All of the Redis commands issued within the closure will be executed in a single, atomic transaction:

use Redis;
use Illuminate\Support\Facades;

Facades\Redis::transaction(function (Redis $redis) {
    $redis->incr('user_visits', 1);
    $redis->incr('total_visits', 1);
});

Warning
When defining a Redis transaction, you may not retrieve any values from the Redis connection. Remember, your transaction is executed as a single, atomic operation and that operation is not executed until your entire closure has finished executing its commands.

#Lua Scripts

The eval method provides another method of executing multiple Redis commands in a single, atomic operation. However, the eval method has the benefit of being able to interact with and inspect Redis key values during that operation. Redis scripts are written in the Lua programming language.

The eval method can be a bit scary at first, but we'll explore a basic example to break the ice. The eval method expects several arguments. First, you should pass the Lua script (as a string) to the method. Secondly, you should pass the number of keys (as an integer) that the script interacts with. Thirdly, you should pass the names of those keys. Finally, you may pass any other additional arguments that you need to access within your script.

In this example, we will increment a counter, inspect its new value, and increment a second counter if the first counter's value is greater than five. Finally, we will return the value of the first counter:

$value = Redis::eval(<<<'LUA'
    local counter = redis.call("incr", KEYS[1])

    if counter > 5 then
        redis.call("incr", KEYS[2])
    end

    return counter
LUA, 2, 'first-counter', 'second-counter');

Warning
Please consult the Redis documentation for more information on Redis scripting.

#Pipelining Commands

Sometimes you may need to execute dozens of Redis commands. Instead of making a network trip to your Redis server for each command, you may use the pipeline method. The pipeline method accepts one argument: a closure that receives a Redis instance. You may issue all of your commands to this Redis instance and they will all be sent to the Redis server at the same time to reduce network trips to the server. The commands will still be executed in the order they were issued:

use Redis;
use Illuminate\Support\Facades;

Facades\Redis::pipeline(function (Redis $pipe) {
    for ($i = 0; $i < 1000; $i++) {
        $pipe->set("key:$i", $i);
    }
});

#Pub / Sub

Laravel provides a convenient interface to the Redis publish and subscribe commands. These Redis commands allow you to listen for messages on a given "channel". You may publish messages to the channel from another application, or even using another programming language, allowing easy communication between applications and processes.

First, let's setup a channel listener using the subscribe method. We'll place this method call within an Artisan command since calling the subscribe method begins a long-running process:

<?php

namespace App\Console\Commands;

use Illuminate\Console\Command;
use Illuminate\Support\Facades\Redis;

class RedisSubscribe extends Command
{
    /**
     * The name and signature of the console command.
     *
     * @var string
     */
    protected $signature = 'redis:subscribe';

    /**
     * The console command description.
     *
     * @var string
     */
    protected $description = 'Subscribe to a Redis channel';

    /**
     * Execute the console command.
     */
    public function handle(): void
    {
        Redis::subscribe(['test-channel'], function (string $message) {
            echo $message;
        });
    }
}

Now we may publish messages to the channel using the publish method:

use Illuminate\Support\Facades\Redis;

Route::get('/publish', function () {
    // ...

    Redis::publish('test-channel', json_encode([
        'name' => 'Adam Wathan'
    ]));
});

#Wildcard Subscriptions

Using the psubscribe method, you may subscribe to a wildcard channel, which may be useful for catching all messages on all channels. The channel name will be passed as the second argument to the provided closure:

Redis::psubscribe(['*'], function (string $message, string $channel) {
    echo $message;
});

Redis::psubscribe(['users.*'], function (string $message, string $channel) {
    echo $message;
});

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