restore with latest

[deitch]

Fixes #436

I am not 100% sure that this will work. The logic is mostly right, but getting tests in place is complex. If you want to try it @ZetaMap and see if it does it, that would be good enough for now.

CI should check that there are no regressions, although restore tests have always been thin.

[ZetaMap]

mmm i'm not sure if the ?latest url parameter. a cli parameter is not good? or you want to let the server choose the latest backup, or it's not possible to list the files and choose the latest according to the file format?

[deitch]

I am not sure myself. I originally went down a different path, and had another parameter. It then got messy with extra parameter and config. Not terrible, but messy. There is something nice about the URL being self-contained to say "here is what you should take", and it either being a path to an actual file, or to a root that might contain multiple files - could be a directory, or prefix in S3, or even file glob (although globs are not supported right now) - and it indicates what to take.

It also makes it a bit easier to implement, but that is a secondary concern.

[ZetaMap]

Mmm ok, but the server will need to have some additional configuration to be able to understand the parameter in the URL and decide what to do.
it's not really practical.

[deitch]

the server will need to have some additional configuration to be able to understand the parameter in the URL and decide what to do.

What do you mean? Which server will need additional configuration? Not the database, and not the target (smb, s3, file), because those all are parsed internal to mysql-backup anyways.

[ZetaMap]

Mmmm but if it's parsed, why using an url option instead of a command option? I don't understand.

[deitch]

Mainly because --target <target> encapsulates the target as a single URL. It is simpler to still have a single URL:

• https://example.com/foo/bar/file1.tgz = restore this exact file /foo/bar/file1.tgz
• https://example.com/foo/bar?latest = look in /foo/bar for the most recent file and restore it

Single URL captures it all.

Is there a particular reason to object to it? What is the advantage of any other approach?