Add Redis and Memcached support

[wojtekn]

Related issues

Fixes STU-1178

Proposed Changes

I propose to enable Redis and Memcached PHP extensions for all Studio sites.

Testing Instructions

Confirm:

• Sites can be created, started, stopped, deleted
• Redis and Memcached are now available to WordPress installations on Studio sites without UI changes.
• Studio CLI works

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[wpmobilebot]

📊 Performance Test Results

Comparing 5d4b955 vs trunk

site-editor

Metric	trunk	5d4b955	Diff	Change
load	1436.00 ms	1475.00 ms	+39.00 ms	⚪ 0.0%

site-startup

Metric	trunk	5d4b955	Diff	Change
siteCreation	7121.00 ms	7150.00 ms	+29.00 ms	⚪ 0.0%
siteStartup	3945.00 ms	3958.00 ms	+13.00 ms	⚪ 0.0%

---

Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change (<50ms diff)

[ivan-ottinger]

All site operations still work well. I did not observe any issues with the CLI.

Regarding the reported slowdown of the site creation (+1010.00 ms | 🔴 14.2%), I run the performance test locally (3 rounds) and here are the results:

  site-editor
  ┌────────┬─────────┬─────────┬───────────────┐
  │ Metric │  trunk  │ branch  │     Diff      │
  ├────────┼─────────┼─────────┼───────────────┤
  │ load   │ 2918 ms │ 1446 ms │ -50.4% faster │
  └────────┴─────────┴─────────┴───────────────┘
  site-startup
  ┌──────────────┬─────────┬─────────┬─────────────┐
  │    Metric    │  trunk  │ branch  │    Diff     │
  ├──────────────┼─────────┼─────────┼─────────────┤
  │ siteCreation │ 7044 ms │ 7047 ms │ +3 ms (~0%) │
  ├──────────────┼─────────┼─────────┼─────────────┤
  │ siteStartup  │ 3908 ms │ 3910 ms │ +2 ms (~0%) │
  └──────────────┴─────────┴─────────┴─────────────┘

So in that front it is looking good as well. 🙂

[sejas]

The code looks good to me, and Sites start correctly, and I didn’t notice any performance degradation., although I’m not sure how to use Redis in my Studio sites. When installing https://wordpress.org/plugins/redis-cache/, I see the same error message as in trunk Redis is unreachable: Error while reading line from the server. [tcp://127.0.0.1:6379].

Same overview results for trunk and this branch:

The plugin diagnostics show the PhpRedis is installed for this PR:

Before / After Diff

Status: Not enabled
Client: 
Drop-in: Not installed
Disabled: No
-PhpRedis: Not loaded
+PhpRedis: 6.3.0
Relay: Not loaded
Predis: 2.4.0
Credis: Not loaded
PHP Version: 8.3.30
Plugin Version: 2.7.0
Redis Version: Unknown
Multisite: No
Metrics: Disabled
Metrics recorded: 0
Filesystem: Writable
WP_REDIS_PLUGIN_PATH: "/wordpress/wp-content/plugins/redis-cache"
Drop-ins: [
    "SQLite integration (Drop-in) v1.0.0 by WordPress Performance Team"
]

[sejas]

I think this is an unrelated change 🤔

[wojtekn]

Yeah, removed.

[fredrikekelund]

Redis and Memcached are now available to WordPress installations on Studio sites without UI changes

@wojtekn, how do we actually test this?

[wojtekn]

@wojtekn, how do we actually test this?

I dumped phpinfo() in the wp-config.php and confirmed the extension data is there, but based on @sejas comment shared above, it seems we need to check it it really works.

[wojtekn]

@sejas @fredrikekelund I tested Redis and confirmed it works fine:

1. Start Redis server using Docker

docker run --name studio-redis -p 6379:6379 -d redis                                                                                          

2. Start Studio from this PR
3. Create a new site
4. Open WP Admin and install "Redis Object Cache" plugin
5. Configure Redis server address in wp-config.php file:

define( 'WP_REDIS_HOST', '127.0.0.1' );
define( 'WP_REDIS_PORT', 6379 );

6. Enable Redis as object cache in WP Admin

I see the following in backend:

And CLI:

% studio wp redis status
Status: Connected
Client: PhpRedis (v6.3.0)
[...]

I see the cache data in redis-cli, too:

% redis-cli
127.0.0.1:6379> KEYS *
 1) "wp:site-transient:theme_roots"
 2) "wp:terms:last_changed"
[...]

[sejas]

@wojtekn, thanks for expanding on the testing steps. I can confirm that I was able to start a Redis server in Docker using docker run -d --name redis -p 6379:6379 redis:latest, and my Studio site successfully connected to it.

One last observation is that we’re enabling Redis and Memcached for all sites, even though most of them won’t use them. I didn’t observe any performance impact during my testing, but it’s something to keep in mind.

[wojtekn]

One last observation is that we’re enabling Redis and Memcached for all sites, even though most of them won’t use them. I didn’t observe any performance impact during my testing, but it’s something to keep in mind.

Yes, performance metrics don't show any decrease.