The following upgrade procedure was used in T2174:

cd /srv/mediawiki
git pull

cd /srv/mediawiki/extensions
ls -1 | grep -v README | xargs -I {} sh "cd {} && git pull"

cd /srv/mediawiki/skins
ls -1 | grep -v README | xargs -I {} sh "cd {} && git pull"

That could help if we've an helper script mediawiki-full-upgrade to automate this.

If we want to furthermore automate files:

cd /srv/mediawiki
composer update
npm update

To be able to run npm update, /srv/mediawiki/package-lock.json MUST be writable by mediawiki user.

And finally we could automate the procedures:

<command to list all databases> | xargs -I {} mw {} update