Crate k8s_controller

This crate implements a lightweight framework around kube_runtime::Controller which provides a simpler interface for common controller patterns. To use it, you define the data that your controller is going to operate over, and implement the Context trait on that struct:

#[derive(Default, Clone)]
struct PodCounter {
    pods: Arc<Mutex<BTreeSet<String>>>,
}

impl PodCounter {
    fn pod_count(&self) -> usize {
        let mut pods = self.pods.lock().unwrap();
        pods.len()
    }
}

#[async_trait::async_trait]
impl k8s_controller::Context for PodCounter {
    type Resource = Pod;
    type Error = kube::Error;

    const FINALIZER_NAME: &'static str = "example.com/pod-counter";

    async fn apply(
        &self,
        client: Client,
        pod: &Self::Resource,
    ) -> Result<Option<Action>, Self::Error> {
        let mut pods = self.pods.lock().unwrap();
        pods.insert(pod.meta().uid.as_ref().unwrap().clone());
        Ok(None)
    }

    async fn cleanup(
        &self,
        client: Client,
        pod: &Self::Resource,
    ) -> Result<Option<Action>, Self::Error> {
        let mut pods = self.pods.lock().unwrap();
        pods.remove(pod.meta().uid.as_ref().unwrap());
        Ok(None)
    }
}

Then you can run it against your Kubernetes cluster by creating a Controller:

let kube_config = Config::infer().await.unwrap();
let kube_client = Client::try_from(kube_config).unwrap();
let context = PodCounter::default();
let controller = k8s_controller::Controller::namespaced_all(
    kube_client,
    context.clone(),
    watcher::Config::default(),
);
task::spawn(controller.run());

loop {
    println!("{} pods running", context.pod_count());
    sleep(Duration::from_secs(1));
}

Structs

Controller

The Controller watches a set of resources, calling methods on the provided Context when events occur.

Traits

Context

The Context trait should be implemented in order to provide callbacks for events that happen to resources watched by a Controller.