[Proposal] Gitea repository storage abstract

[lunny]

Current status

Gitea's repositories are stored in a single directory that is configured via app.ini.

#24783 would like hot/cold storage. i.e. repo archived repository will be stored in a HDD but the hot repository will be stored in SSD

#22532 would like to store the repository in different directories with a hash

#13791 request a distributed git storages like gitaly

The problems

• setting.Repository.RepoRootPath has been used by many places which fixed the usage to visit the repository
• modules/git.Command has an option Dir which fixed the git command run directory

Resolution

• First step, build an abstract level to visit repositories and avoid visit setting.Repository.RepoRootPath directly
• Most function will accept a relative repository path
• Refactor git.Command to visit the abstract level

Others

Some ideas are storing git repositories with repository id but not username/reponame, how to handle it?

[6543]

to have nice proxy-pattern and can switch between different git backend's ...

TODO:

• 1. move current implementation in subpackage
• 2. move types into own subpackage
• 3. define an engine
• 4. migrate to engine in steps

[6543]

this also might enable to use https://gitlab.com/gitlab-org/gitaly for us ... or split gitea int microservices ... (as one option)

[6543]

• instead of individual git version checks all over the code - save capabilitis and let it report the engine

[6543]

Sorry somebody else might pick it up befor me ... i still intent to pick it up again if not addressed later :)

[lunny]

I think this could be replaced by #29033