Add RNode implementation of label and annotation selectors.

kyaml/yaml/internal/k8sgen/doc.go

@@ -0,0 +1,27 @@
+// Copyright 2020 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+// Package k8sgen contains code generated by copying bits of k8s.io code.
+// The copier is in generator/main.go.
+//
+// kyaml (and indirectly kustomize) wants to reuse the k/k label selection code.
+// Labels and annotations are a key part of k8s metadata.
+//
+// kyaml cannot depend on it via a normal Go import because kubectl will
+// depend on kyaml eventually (see kubernetes-sigs/kustomize/issues/1500).
+// While kubectl remains in the k/k repo, it depends on local relative symlinked
+// path to a 'staging' version of k8s.io code.  No code imported by kubectl can
+// refer to any other version of k8s.io code.
+//
+// So to do what that code does, kyaml must either reimplement it or copy it.
+// When/if kubectl is finally extracted from k/k to its own repo, it can
+// depend on apimachinery code via normal imports, and so can kyaml.
+// At that point, this copy (and copying mechanism) can be dropped.
+//
+// Until then, if a bug is found in a particular instance of copied k8s.io
+// (unlikely, since this code is old and stable), just increment
+// apiMachineryVersion below to match the fixed version, possibly change
+// the files copied, re-generate, and if need be adjust call points.
+//
+//go:generate go run generator/main.go
+package k8sgen