Feature Request: Add support for PHP extensions required for object caching

[shivapoudel]

What

Add support for PHP object caching extensions within WordPress Studio:

• Memcached (php-memcached)
• PhpRedis (php-redis)

These extensions are required by popular object caching plugins like Redis Object Cache and W3 Total Cache to enable persistent object caching in WordPress.

Why

Object caching is a critical performance optimization used in production WordPress environments. Many hosting providers (including WordPress.com, Pressable, WP Engine, Pantheon) offer Redis or Memcached for object caching.

Without these extensions in Studio, developers cannot:

1. Test object caching behavior locally before deploying to production
2. Debug caching-related issues that only manifest with persistent object cache enabled
3. Develop and test object cache drop-ins (e.g., object-cache.php)
4. Ensure plugin/theme compatibility with cached environments

Given Studio Sync's integration with WordPress.com and Pressable (which offer object caching), having these extensions would allow more accurate local replication of production environments and bring Studio closer to feature parity with tools like Local by Flywheel, DevKinsta, DDEV, and Lando.

How

Possible implementation approaches:

1. Built-in toggle in site settings to enable object caching extensions
2. Local Redis/Memcached service bundled or optionally installable alongside WordPress Playground
3. Configuration option to connect to an external Redis/Memcached server running on the host machine

No mockups available, but the feature could potentially be exposed as a checkbox or toggle in the site settings panel similar to how PHP version selection works.

[wojtekn]

Hey @shivapoudel ! Thanks for adding the feature request. We will review if and how those PHP extensions could be added to the Playground. Having them would let you connect the Studio site to an external Redis/Memcached server running on your machine.

The good news is that you can already use the Redis Object Cache plugin in your Studio site with a Redis server - it doesn't require PhpRedis extension, and it ships Predis. Here is my Studio site running with Redis:

[shivapoudel]

@wojtekn While Predis works as a pure-PHP Redis client, there are notable trade-offs:

1. Performance: PhpRedis is a C extension and significantly faster than Predis—benchmarks show it can be 2-5x faster for high-throughput scenarios due to native socket handling and serialization
2. Production parity: Most managed WordPress hosts (WP Engine, Pantheon, WordPress.com) use PhpRedis, not Predis. Testing with Predis locally doesn't replicate production behavior accurately
3. Memcached has no pure-PHP alternative: Unlike Redis, WP Cached Memcached (Automattic's own solution) requires the memcached extension - there's no Predis equivalent

Rather than bundling specific extensions, consider allowing developers to install PHP extensions themselves. This approach:

• Keeps Studio lightweight by not bundling services developers may not need
• Provides flexibility for edge cases (e.g. APCu or OPcache)
• Mirrors real-world workflows where developers configure their environment

A simple UX could be:

1. A "PHP Extensions" section in site settings
2. List common extensions with install/enable toggles
3. Or an "Advanced" option to specify custom extensions

Suggested Implementation

Building on the UX pattern from #2242 (Xdebug support), a unified "PHP Settings" section could be added to site settings:

Simple UI:

Setting	Status	Actions
PHP Version	8.2	[Change]
Xdebug	✅ Enabled	[Disable]
Redis	❌ Not installed	[Install]
Memcached	❌ Not installed	[Install]
+ Add extension

Advanced users: A studio.json configuration for full control:

{
  "php": {
    "version": "8.3",
    "xdebug": {
      "enabled": true,
      "mode": "debug",
      "start_with_request": "yes",
      "client_port": 9003
    },
    "extensions": ["redis", "memcached", "imagick", "intl"],
    "ini": {
      "opcache.memory_consumption": 256,
      "memory_limit": "512M"
    }
  }
}

This would consolidate PHP version selection, Xdebug configuration, and extension management into a single cohesive settings area—providing a streamlined experience for general users while giving advanced users full control via configuration file.

The extension list shouldn't be hardcoded—developers should be able to install any extension available from PECL or system packages. This gives Studio the flexibility to match any production environment configuration.