Dynamic Reflector support

[night-crawler]

Hi.

Currently, I'm trying to create a dynamic reflector for a CRD. The problem is that I don't know CRD's GVK in compile time, so I can't create a struct the usual way.

Here comes the next approach with creating a reflector of a DynamicObject. The problem here is that reflector::store() requires K implementing the Default trait, though discovery::ApiResource does not implement it at the moment. The snippet below does not compile, though after patching ApiResource derives with Default, it does.

pub async fn crd_store() -> Result<()> {
    let client = Client::try_default().await?;

    let group = "stable.example.com";
    let version = "v1";
    let kind = "CronTab";

    let gvk = GroupVersionKind::gvk(group, version, kind);
    let (ar, caps) = discovery::pinned_kind(&client, &gvk).await?;

    let api = Api::<DynamicObject>::all_with(client, &ar);

    let lp = ListParams::default();

    // the trait bound `ApiResource: Default` is not satisfied
    // the trait `Default` is not implemented for `ApiResource`
    let (reader, writer) = reflector::store();
    let rf = reflector(writer, watcher(api, lp));

    tokio::spawn(async move {
        loop {
            let nodes = reader.state().iter().map(|r| r.name_any()).collect::<Vec<_>>();
            println!("Current {} nodes: {:?}", nodes.len(), nodes);
            tokio::time::sleep(std::time::Duration::from_secs(10)).await;
        }
    });

    let mut rfa = rf.applied_objects().boxed();
    while let Some(event) = rfa.try_next().await? {
        if caps.scope == Scope::Cluster {
            println!("saw {}", event.name_any());
        } else {
            println!("saw {} in {}", event.name_any(), event.namespace().unwrap());
        }
    }

    Ok(())
}

Is there any other way to create a dynamic reflector without patching? If no, can Default be added to the ApiResource implementation?

Many thanks.

[clux]

Hey there! The reflector::store() fn is only a helping way to construct a Writer and a Store from this writer using Writer::default. The Writer::default call does genuinely require the default bound on the dynamic type - and as such only helps out the static cases - but you can create a Writer directly Writer::new(dyntype) using your ApiResource as a dyntype.