watcher-test.js

const k8s = require("@kubernetes/client-node");

async function run() {
  const kc = new k8s.KubeConfig();
  kc.loadFromDefault();
  const appsApi = kc.makeApiClient(k8s.AppsV1Api);
  const watch = new k8s.Watch(kc);
  const deploymentCache = new k8s.ListWatch(
    `/apis/apps/v1/namespaces/default/deployments`,
    watch,
    () => {
      console.log("ls");
      return appsApi.listNamespacedDeployment(
        "default",
        undefined,
        undefined,
        undefined,
        undefined,
        undefined,
        undefined,
        undefined,
        10
      );
    },
    false
  );
  deploymentCache.on("error", (e) => {
    if (e.metadata.name === "sql-engine-coordinator") {
      console.log("error", e.spec.replicas);
    }
  });
  deploymentCache.on("delete", (e) => {
    if (e.metadata.name === "sql-engine-coordinator") {
      console.log("delete", e.spec.replicas);
    }
  });
  deploymentCache.on("add", (e) => {
    if (e.metadata.name === "sql-engine-coordinator") {
      console.log("add", e.spec.replicas);
    }
  });
  deploymentCache.on("update", (e) => {
    if (e.metadata.name === "sql-engine-coordinator") {
      console.log("update", e.spec.replicas);
    }
  });
  deploymentCache.start();
  return true;
}

run().then(console.log).catch(console.log);