How to set up a watcher on a CR?

[AndreasDavour]

Using:

let api = Api::<Pod>::default_namespaced(client);
let stream = watcher(api, Config::default()).default_backoff().applied_objects();

I can create a client connection, and using that tell my watcher what kind of api objects I care about. Now, if I have created a CRD and loaded it in my cluster, Pods are not all I could be interested in watching for, right?

So, If I have a Book CR created in my cluster, how do I write the code above?

Api::<Book>::deafult_namespaced(client)

doesn't work. I'm missing a step, am I not? Documentation, explanations and examples welcome.

[clux]

Not completely sure I understand the issue, but generally you create one Api for the object/CR, as you have done and feed it to one watcher and things should all work if you have installed the crd yaml, and are remembering to poll the watcher future (via a for_each or a for loop).

The crd_reflector example should do basically what you want for CR watches in https://github.com/kube-rs/kube/blob/main/examples/crd_reflector.rs (just ignore the reflect/reflector calls and its spawned tokio::task).

[AndreasDavour]

I have written a CRD.yaml and loaded it into my cluster, but not in rust.

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::try_default().await?;
    let tracks: Api<KCDTrack2> = Api::all(client);
    let watcher = watcher(tracks, Default::default());

But, when I try to compile it, rustc complains:

error[E0412]: cannot find type `KCDTrack2` in this scope
  --> src/main.rs:31:19
   |
31 |     let pods: Api<KCDTrack2> = Api::all(client);
   |                   ^^^^^^^^^ not found in this scope

Which kind of makes sense. But, k8s API knows about that CRD. So, how do I make rustc aware of that new Kind? I feel like I'm missing something, and it's probably a mix of lack of rust and lack of k8s knowledge. I checked the example of the reflector, but I don't see what I'm missing. The only that code does is the same I've done with "kubectl apply -f crd.yaml" is it not?

[clux]

you need rust structs corresponding to the openapi types of the schema which is contained your CR. if you're not writing them yourself (and using the rust structs to generate the schema/customresourcedefinition), then you can instead use kopium to generate rust structs from the customresourcedefinition.

[AndreasDavour]

Right, if the type is not defined in the kube::api namespace, I need to provide a struct for it.

But if I have a struct defined, like this:

#[derive(CustomResource, Deserialize, Serialize, Clone, Debug, JsonSchema)]
#[kube(group = "clux.dev", version = "v1", kind = "Foo", namespaced)]
pub struct FooSpec {
    name: String,
    info: String,
}

Then I should be able to create a client on that type, in this case 'Foo'?

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::try_default().await?;
    let tracks: Api<Foo> = Api::all(client);

Because that derive macro is creating the type for me, is it not?
I still get that "not found in this scope" error.

Am I missing something about how the types work with that macro?

[clux]

that's how it should work yeah. looks right to me.
maybe you need to import it from the module that defines FooSpec (if you have different files)?

[AndreasDavour]

Nah, it's the same file.

Hmm. Then I'm on the correct track. I wonder why it doesn't work?

I will see if I can create a full test case, as my files are filled with commented out blocks and lots of stuff apart from this problem.

[AndreasDavour]

Re-written without all the incremental changes, it works like I expected. Thanks a lot for clarifying that for me!