This is a draft proposal, and likely needs more polish

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

Many stores provide the ability to associate arbitrary user-defined attributes with objects, it would be useful to expose this.

Describe the solution you'd like

I would like to propose a new put_opts call, in a similar vein to the existing get_opts. This would take a PutOptions

pub struct PutOptions {
    pub metadata: HashMap<String, String>
}

Stores that can't store metadata should return an error if passed metadata, and ObjectMeta should be updated to include such metadata.

Unix systems can likely make use of xattr to store user metadata

We will likely need to restrict the key names in some manner

Describe alternatives you've considered

Additional context

apache/arrow-rs#4498 also calls for some sort of put_opts style API

#294 would benefit from this functionality