Change 598901 had a related patch set uploaded (by Art-Baltai; owner: Art-Baltai):
[mediawiki/core@master] PoC that allows the extension to add a new type of database to the installer

https://gerrit.wikimedia.org/r/598901

Worked PoC with minimal changes
https://gerrit.wikimedia.org/r/c/mediawiki/core/+/598901

Test extension with db-engine: https://github.com/artbaltai/mediawiki-dbext

Tested with LocalSettings.php:

<?php
wfLoadExtension( 'DBExt' );

Technical minuses:

• final LocalSettings.php is created without existed parameters
• We need to make a universal hook injection to the installer (not only for DBType injection)
• We need to use the correct method to read extension.json (now it is a reader from a temporary queue)
• We need to use the hooks mechanism
• We need to create some method like isLocalSettingsConfigured
• autotest is broken: Fatal error: Interface 'Wikibase\Store' not found in /workspace/src/extensions/Wikibase/repo/includes/Store/Sql/SqlStore.php on line 64 - I did not touch this file

Here is more detail on the approach we discussed:

• installer should not require existing LocalSettings.php file before installation
• installer should not require code injected via hook into installer
• installer will scan extension directory for extension.json files that implement database support
  • perhaps use type field (https://www.mediawiki.org/wiki/Manual:Extension.json/Schema#type)
  • non-standard location for extension directory is out of scope
• if a database loaded from an extension is selected, then when the installer prompts for which extensions/skins to enable:
  • the selected database extension should be pre-selected and it should not be possible to disable it
  • no other database extensions should be listed/selectable
• selected extensions are loaded before the database is created
  • determine if there is anything else that needs to happen for this to work correctly
• it should be possible to check in CI that an extension that is marked as a database extension implements required interfaces/hooks for that to be so

Definition of done:

• proof of concept of the above approach
• decision on how to identify a database extension in extension.json
• document what interfaces/hooks must be implemented in an extension for it to satisfy requirements to provide database support

Change 601650 had a related patch set uploaded (by Art-Baltai; owner: Art-Baltai):
[mediawiki/core@master] PoC that allows the extension to add a new type of database to the installer from extension without config

https://gerrit.wikimedia.org/r/601650

Change 598901 abandoned by Art-Baltai:
PoC that allows the extension to add a new type of database to the installer

Reason:
works, but not actual by requirements

https://gerrit.wikimedia.org/r/598901

Change 604477 had a related patch set uploaded (by Art-Baltai; owner: Art-Baltai):
[mediawiki/core@master] Add a new type of database to the installer from extension

https://gerrit.wikimedia.org/r/604477

Change 601650 abandoned by Art-Baltai:
PoC that allows the extension to add a new type of database to the installer from extension without config

Reason:
see https://gerrit.wikimedia.org/r/c/mediawiki/core/ /604477

https://gerrit.wikimedia.org/r/601650

@Helga_sf , will your team reassign Art Baltai's open tasks?