Add support for Redis database selection in MediaWiki RedisBagOStuff
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	Tessus
	Jun 2 2017, 9:02 PM

Description

The REDIS backend RedisConnectionPool.php and RedisBagOStuff.php do not support to select a DB index.

I'd like to add an additional connection option that allows just that. How do you like the option name dbindex?

e.g.:

$wgObjectCaches['redis'] = array(
    'class'                => 'RedisBagOStuff',
    'servers'              => array( '127.0.0.1:6379' ),
    // 'connectTimeout'    => 1,
    // 'persistent'        => false,
    // 'password'          => 'secret',
    // 'automaticFailOver' => true,
    // 'dbindex'           => 0,
);

I can code it myself and send a PR. What do you think?

Details

	Subject	Repo	Branch	Lines +/-
	redis, objectcache: Allow using 'db' option to select redis database.	mediawiki/core	master	+12 -1

Customize query in gerrit

Related Objects

Duplicates Merged Here: T202484: Add ability to select redis database

Event Timeline

Tessus created this task.Jun 2 2017, 9:02 PM

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptJun 2 2017, 9:02 PM

Aklapper added a project: MediaWiki-General.Jun 3 2017, 12:23 PM

Change 617123 had a related patch set uploaded (by Hyperzlib; owner: Hyperzlib):
[mediawiki/core@master] redis, objectcache: Allow using 'db' option to select redis database.

https://gerrit.wikimedia.org/r/617123

gerritbot added a project: Patch-For-Review.Jul 29 2020, 1:59 PM

RazeSoldier assigned this task to Hyperzlib.Jul 29 2020, 2:49 PM

RazeSoldier edited projects, added MediaWiki-libs-BagOStuff; removed MediaWiki-General.

RazeSoldier moved this task from General to libs/objectcache on the MediaWiki-libs-BagOStuff board.

I'm not entirely sure what this is for since MediaWiki generally does namespacing by prefix instead of separate DBs. What is the benefit or motivation for wanting this? Are there separate security/permission credentials?

Tagging PE to decide on this further.

I'll look this over.

@Krinkle @eprodromou This would be useful to have. This isn't a security feature since can't say that a particular client only has access to a particular database, but more an interoperability feature with other (non-MediaWiki) applications that are making use of the same redis instance just in case they happen to use the same keyspaces (unlikely, but possible). It could also be useful when sharing a single redis instance across multiple MediaWiki installations where it's desired to not share certain things (such as rate limits) across all of those wikis because they are meant to be independent and not part of a farm.

Both uses cases caused me to comment here as I was looking into a way to select the database index and stumbled across this task. I'm hosting a handful of independent wikis where I do not wish to share rate limiting information between them. I'm also hosting some non-MediaWiki applications that can make use of redis, and I didn't want to have to dig into the code for all of them to ensure there would be no possible overlap in the namespaces used in keys.

While I could spin up multiple redis instances (one per application), it'd be far easier from a systems management perspective to have a single instance for everything.

Aklapper removed • eprodromou as the assignee of this task.Apr 1 2021, 5:51 AM

Krinkle moved this task from libs/objectcache to General on the MediaWiki-libs-BagOStuff board.Jan 22 2022, 11:25 PM

Restricted Application added a project: Performance-Team. · View Herald TranscriptJan 22 2022, 11:25 PM

Krinkle merged a task: T202484: Add ability to select redis database.Jan 24 2022, 7:45 PM

Krinkle added a subscriber: TazzyTazzy.

Krinkle assigned this task to aaron.Jan 24 2022, 8:18 PM

The feature seems to be discouraged* by the author of redis, and doesn't gain much over key prefixes (MediaWiki code using BagOStuff already uses ones based on $wgDBname/$wgDBprefix and configurable IDs) or multiple redis instances.