Dear Sébastien,
I am currently trying your extension to setup a monoversion wikifarm within my MediaWiki 1.23 installation (this is a migration project, too...) on a CentOS 7 machine.
The wiki code lives in `/var/www/html/wiki.ou.site.de/w`
Following the docs I did:
# Install the extension in `extensions` folder and ran `composer` to install the yaml dep.
# Shuffled around the `LocalSettings.php` files
# Used the monoversion template for `farms.yaml`, put that in `extensions/MediaWikiFarm/config`, edited the `server` string to match my host.
# Added following to the `LocalSettings.php`: `$wgMediaWikiFarmConfigDir = '/var/www/html/wiki.ou.site.de/w/extensions/MediaWikiFarm/config';`
First nothing worked, until I added `$wgMediaWikiFarmCacheDir = false;`, which seems to be related to your last comment on https://www.mediawiki.org/wiki/User_talk:Seb35#MediaWikiFarm_on_MediaWiki-Vagrant.
After that, at least my main page was showing up, but no CSS, JS, etc was loaded. Looking into the Firefox Debugger I found many Error 500 statuses for these (pointing to load.php).
Looking inside `/var/log/messages` I found:
```
mediawikifarm: Logging parameter must be false or a string
mediawikifarm: Only explicitly-defined wikis declared in existence lists are allowed in monoversion mode.
mediawikifarm: Only explicitly-defined wikis declared in existence lists are allowed in monoversion mode.
mediawikifarm: Only explicitly-defined wikis declared in existence lists are allowed in monoversion mode.
```
After setting `$wgMediaWikiFarmSyslog = 'mediawikifarm';` inside `LocalSettings.php`, that error went away.
Looking up the other error lead my to [[ https://github.com/wikimedia/mediawiki-extensions-MediaWikiFarm/blob/e819db74970e444ecd3f2953fcf4a2870fc31a74/src/MediaWikiFarm.php#L1072 | Line 1072 of `src/MediaWikiFarm.php` ]]
Digging into the code, I wondered why `$explicitExistance` is not true and I think the reason is that with the default monoversion template for `farms.yaml` there is no hash `variables` given, which results in `$explicitExistance = null` ([[ https://github.com/wikimedia/mediawiki-extensions-MediaWikiFarm/blob/e819db74970e444ecd3f2953fcf4a2870fc31a74/src/MediaWikiFarm.php#L912 | Line 912 of `src/MediaWikiFarm.php` ]])
So: shall I fix my farms.yaml and fix the template, too (would create a merge request for this) or should the code be fixed for this case?
Thanks for your work and help,
Cheers,
Oliver