It would be useful to have a parameter to ignore existing LocalSettings.php.

In my case, also a wiki_farm, I run many wikis on the same MW codebase, and I have a script to create new wiki instances.

While trying to retrofit my instance creation script to use maintenance/install.php, I found out that there's no way to make it ignore the existing LocalSettings.php file in the shared codebase, which is effectively a dispatcher to instance-specific configuration files.

I expected that specifying --conf to a path where no LocalSettings.php file existed, would do the trick, but it seems that this option is ignored.

I haven't tested it myself, but we recently added MW_CONFIG_FILE as env variable in MediaWiki core. That either is, or perhaps should be, a way to influence this.

While general maintenance scripts do take a --conf option, the install.php script is special and I think understandably ignores those as they are primarily for existing wikis. I don't think it is intentionally ignored and indeed it seems sensible to try to make that work at the same time (or to unset the inherited parameters to avoid confusion).

An environment variable such as MW_CONFIG_FILE was indeed on my wishlist! It would simplify some farm setups.

As of 1.35.5, all mentions of MW_CONFIG_FILE seem to me to be processing PHP variables, rather than an environment variable. This is the case also in Setup.php where setting the value for MW_CONFIG_FILE is expected to take place, for all entry points.

If this is the case, then it would be useless for install.php, unless I write a wrapper for it.

I also found a patch related to T192003, but it doesn't seem to have been merged. which is expected, since it is not the right place to do it.

Here is a past change someone made to mediawiki install files to allow this behavior: https://www.mediawiki.org/wiki/Topic:Vn3phnl79hyleo6s

idk why bug bot didn't link this but this exists: https://gerrit.wikimedia.org/r/c/mediawiki/core/+/952276

Change 952276 had a related patch set uploaded (by Aklapper; author: Lectrician1):

[mediawiki/core@master] Implement installing MediaWiki with an existing LocalSettings from CLI

https://gerrit.wikimedia.org/r/952276

Because the commit message did not follow https://www.mediawiki.org/wiki/Gerrit/Commit_message_guidelines :)

I'm going to work on T352113, which I think is basically the same as this task for third party purposes, except that it uses a new maintenance script, and so has fewer backwards compatibility issues.