[Proposal] Gitea subcommand for installation

[lunny]

Feature Description

As Gitea's configuration becomes more and more and once some configuration changes, gitea needs to be restarted. So we introduced database-based global configuration in #18058 . But once most of system configurations have been moved to database-based global configuration. For those who want to quickly set up a predefined Gitea instance, it becomes very difficult. Then I suppose we could have a subcommand which could be named install or init. i.e.

./gitea install --config gitea.yml

The subcommand will become an alternative choice of the current Web-based installation guide. It accepts a YAML configuration file. The file could contain all possible app.ini configurations, database-based global configurations and even authentication sources (LDAP, OAuth2), and some default users, orgs and etc.

Screenshots

No response

[wxiaoguang]

I would suggest to improve the db-config (#18058) to a complete solution first, instead of leaving it as a semi-finished approach.

There are some design problems of #18058 :

1. Most uses of it require cache/context, not general enough
2. It causes unsolvable cycle-import if it would be used in some (low-level) packages
3. There is no UI support to migrate more options
4. The performance is not good enough even if there is a cache
5. Difficult to use, the code for each option is always complex

There are too many technical debts in Gitea's code base, the similar things happen again and again: an idea -> try -> incomplete solution gets merged -> difficult to use / have problems -> nobody cares -> unmaintainable legacy code.

[a1012112796]

I think a command like git config is also usefull.