Add APIs for computing status based on fetching resource info from a

cluster

kstatus/wait/doc.go

@@ -0,0 +1,57 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+// Package wait contains functionality for getting the statuses
+// of a list of kubernetes resources. Unlike the status package,
+// the functions exposed in the wait package will talk to a
+// live kubernetes cluster to get the latest state of resources
+// and provides functionality for polling the cluster until the
+// resources reach the Current status.
+//
+// FetchAndResolve will fetch resources from a cluster, compute the
+// status for each of them and then return the results. The list of
+// resources is defined as a slice of ResourceIdentifier, which is
+// an interface that is implemented by the Unstructured type. It
+// only requires functions for getting the apiVersion, kind, name
+// and namespace of a resource.
+//
+// import (
+//   "k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+//   "k8s.io/apimachinery/pkg/types"
+//   "sigs.k8s.io/kustomize/kstatus/wait"
+// )
+//
+// key := types.NamespacedName{Name: "name", Namespace: "namespace"}
+// deployment := &unstructured.Unstructured{
+//   Object: map[string]interface{}{
+//     "apiVersion": "apps/v1",
+//     "kind":       "Deployment",
+//   },
+// }
+// client.Get(context.Background(), key, deployment)
+// resourceIdentifiers := []wait.ResourceIdentifier{deployment}
+//
+// resolver := wait.NewResolver(client)
+// results := resolver.FetchAndResolve(context.Background(), resourceIdentifiers)
+//
+// WaitForStatus also looks up status for a list of resources, but it will
+// block until all the provided resources has reached the Current status or
+// the wait is cancelled through the passed-in context. The function returns
+// a channel that will provide updates as the status of the different
+// resources change.
+//
+// import (
+//   "sigs.k8s.io/kustomize/kstatus/wait"
+// )
+// resolver := wait.NewResolver(client)
+// eventsChan := resolver.WaitForStatus(context.Background(), resourceIdentifiers, 2 * time.Second)
+// for {
+//   select {
+//   case event, ok := <-eventsChan:
+//     if !ok {
+//       return
+//     }
+//     fmt.Printf(event) // do something useful here.
+//   }
+// }
+package wait