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# Predis # [![Software license][ico-license]](LICENSE) [![Latest stable][ico-version-stable]][link-releases] [![Latest development][ico-version-dev]][link-releases] [![Monthly installs][ico-downloads-monthly]][link-downloads] [![Build status][ico-build]][link-actions] [![Coverage Status][ico-coverage]][link-coverage] A flexible and feature-complete [Redis](http://redis.io) client for PHP 7.2 and newer. More details about this project can be found on the [frequently asked questions](FAQ.md). ## Main features ## - Support for Redis from __3.0__ to __7.0__. - Support for clustering using client-side sharding and pluggable keyspace distributors. - Support for [redis-cluster](http://redis.io/topics/cluster-tutorial) (Redis >= 3.0). - Support for master-slave replication setups and [redis-sentinel](http://redis.io/topics/sentinel). - Transparent key prefixing of keys using a customizable prefix strategy. - Command pipelining on both single nodes and clusters (client-side sharding only). - Abstraction for Redis transactions (Redis >= 2.0) and CAS operations (Redis >= 2.2). - Abstraction for Lua scripting (Redis >= 2.6) and automatic switching between `EVALSHA` or `EVAL`. - Abstraction for `SCAN`, `SSCAN`, `ZSCAN` and `HSCAN` (Redis >= 2.8) based on PHP iterators. - Connections are established lazily by the client upon the first command and can be persisted. - Connections can be established via TCP/IP (also TLS/SSL-encrypted) or UNIX domain sockets. - Support for custom connection classes for providing different network or protocol backends. - Flexible system for defining custom commands and override the default ones. ## How to _install_ and use Predis ## This library can be found on [Packagist](http://packagist.org/packages/predis/predis) for an easier management of projects dependencies using [Composer](http://packagist.org/about-composer). Compressed archives of each release are [available on GitHub](https://github.com/predis/predis/releases). ```shell composer require predis/predis ``` ### Loading the library ### Predis relies on the autoloading features of PHP to load its files when needed and complies with the [PSR-4 standard](https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-4-autoloader.md). Autoloading is handled automatically when dependencies are managed through Composer, but it is also possible to leverage its own autoloader in projects or scripts lacking any autoload facility: ```php // Prepend a base path if Predis is not available in your "include_path". require 'Predis/Autoloader.php'; Predis\Autoloader::register(); ``` ### Connecting to Redis ### When creating a client instance without passing any connection parameter, Predis assumes `127.0.0.1` and `6379` as default host and port. The default timeout for the `connect()` operation is 5 seconds: ```php $client = new Predis\Client(); $client->set('foo', 'bar'); $value = $client->get('foo'); ``` Connection parameters can be supplied either in the form of URI strings or named arrays. The latter is the preferred way to supply parameters, but URI strings can be useful when parameters are read from non-structured or partially-structured sources: ```php // Parameters passed using a named array: $client = new Predis\Client([ 'scheme' => 'tcp', 'host' => '10.0.0.1', 'port' => 6379, ]); // Same set of parameters, passed using an URI string: $client = new Predis\Client('tcp://10.0.0.1:6379'); ``` Password protected servers can be accessed by adding `password` to the parameters set. When ACLs are enabled on Redis >= 6.0, both `username` and `password` are required for user authentication. It is also possible to connect to local instances of Redis using UNIX domain sockets, in this case the parameters must use the `unix` scheme and specify a path for the socket file: ```php $client = new Predis\Client(['scheme' => 'unix', 'path' => '/path/to/redis.sock']); $client = new Predis\Client('unix:/path/to/redis.sock'); ``` The client can leverage TLS/SSL encryption to connect to secured remote Redis instances without the need to configure an SSL proxy like stunnel. This can be useful when connecting to nodes running on various cloud hosting providers. Encryption can be enabled with using the `tls` scheme and an array of suitable [options](http://php.net/manual/context.ssl.php) passed via the `ssl` parameter: ```php // Named array of connection parameters: $client = new Predis\Client([ 'scheme' => 'tls', 'ssl' => ['cafile' => 'private.pem', 'verify_peer' => true], ]); // Same set of parameters, but using an URI string: $client = new Predis\Client('tls://127.0.0.1?ssl[cafile]=private.pem&ssl[verify_peer]=1'); ``` The connection schemes [`redis`](http://www.iana.org/assignments/uri-schemes/prov/redis) (alias of `tcp`) and [`rediss`](http://www.iana.org/assignments/uri-schemes/prov/rediss) (alias of `tls`) are also supported, with the difference that URI strings containing these schemes are parsed following the rules described on their respective IANA provisional registration documents. The actual list of supported connection parameters can vary depending on each connection backend so it is recommended to refer to their specific documentation or implementation for details. Predis can aggregate multiple connections when providing an array of connection parameters and the appropriate option to instruct the client about how to aggregate them (clustering, replication or a custom aggregation logic). Named arrays and URI strings can be mixed when providing configurations for each node: ```php $client = new Predis\Client([ 'tcp://10.0.0.1?alias=first-node', ['host' => '10.0.0.2', 'alias' => 'second-node'], ], [ 'cluster' => 'predis', ]); ``` See the [aggregate connections](#aggregate-connections) section of this document for more details. Connections to Redis are lazy meaning that the client connects to a server only if and when needed. While it is recommended to let the client do its own stuff under the hood, there may be times when it is still desired to have control of when the connection is opened or closed: this can easily be achieved by invoking `$client->connect()` and `$client->disconnect()`. Please note that the effect of these methods on aggregate connections may differ depending on each specific implementation. ### Client configuration ### Many aspects and behaviors of the client can be configured by passing specific client options to the second argument of `Predis\Client::__construct()`: ```php $client = new Predis\Client($parameters, ['prefix' => 'sample:']); ``` Options are managed using a mini DI-alike container and their values can be lazily initialized only when needed. The client options supported by default in Predis are: - `prefix`: prefix string applied to every key found in commands. - `exceptions`: whether the client should throw or return responses upon Redis errors. - `connections`: list of connection backends or a connection factory instance. - `cluster`: specifies a cluster backend (`predis`, `redis` or callable). - `replication`: specifies a replication backend (`predis`, `sentinel` or callable). - `aggregate`: configures the client with a custom aggregate connection (callable). - `parameters`: list of default connection parameters for aggregate connections. - `commands`: specifies a command factory instance to use through the library. Users can also provide custom options with values or callable objects (for lazy initialization) that are stored in the options container for later use through the library. ### Aggregate connections ### Aggregate connections are the foundation upon which Predis implements clustering and replication and they are used to group multiple connections to single Redis nodes and hide the specific logic needed to handle them properly depending on the context. Aggregate connections usually require an array of connection parameters along with the appropriate client opti