The main idea behind that was to be able to do more sophisticated
merging for stuff that goes into `postgresql.conf`:
`shared_preload_libraries` is a comma-separated list in a `types.str`
and thus not mergeable. With this change, the option accepts both a
comma-separated string xor a list of strings.
This can be implemented rather quick using `coercedTo` +
freeform modules. The interface still behaves equally, but it allows to
merge declarations for this option together.
One side-effect was that I had to change the `attrsOf (oneOf ...)` part into
a submodule to allow declaring options for certain things. While at it,
I decided to move `log_line_prefix` and `port` into this structure as
well.
This makes sure we don't need any workarounds for running Invidious with a local
PostgreSQL database.
Changing the default user should be fine as the new init script for PostgreSQL automatically
creates the new user and changes the existing database's owner to the new user. The old user
will still linger and must be removed manually.
See also: https://github.com/NixOS/nixpkgs/pull/266270
Invidious uses a strange setup where the database name is different from the system username
for non-explicit reasons.
Because of that, it makes it hard to migrate it to use `ensureDBOwnership`, we leave it to Invidious' maintainers
to pick up the pieces.
