doc.go

// Copyright 2019 The Kubernetes Authors.
// SPDX-License-Identifier: Apache-2.0

// 2019 Nov 06  These notes are somewhat out of date, but left
// for historical purposes need to be updated (or simply removed
// with all the code).  The kubectl integration plan described
// below is no longer the plan of record.
//
// --------
//
// It's possible that kustomize's features will be vendored into
// the kubernetes/kubernetes repo and made available to kubectl
// commands, while at the same time the kustomize program will
// continue to exist as an independent CLI.  Vendoring snapshots
// would be taken just before a kubectl release.
//
// This creates a problem in that freestanding-kustomize depends on
// (for example):
//
//   https://github.com/kubernetes/apimachinery/
//       tree/master/pkg/util/yaml
//
// It vendors that package into
//   sigs.k8s.io/kustomize/vendor/k8s.io/apimachinery/
//
// Whereas kubectl-kustomize would have to depend on the "staging"
// version of this code, located at
//
//   https://github.com/kubernetes/kubernetes/
//       blob/master/staging/src/k8s.io/apimachinery/pkg/util/yaml
//
// which is "vendored" via symlinks:
//   k8s.io/kubernetes/vendor/k8s.io/apimachinery
// is a symlink to
//   ../../staging/src/k8s.io/apimachinery
//
// The staging version is the canonical, under-development
// version of the code that kubectl depends on, whereas the packages
// at kubernetes/apimachinery are periodic snapshots of staging made
// for outside tools to depend on.
//
// apimachinery isn't the only package that poses this problem, just
// using it as a specific example.
//
// The kubectl binary cannot vendor in kustomize code that in
// turn vendors in the non-staging packages.
//
// One way to fix some of this would be to copy code - a hard fork.
// This has all the problems associated with a hard forking.
//
// Another way would be to break the kustomize repo into three:
//
// (1) kustomize - repo with the main() function,
//     vendoring (2) and (3).
//
// (2) kustomize-libs - packages used by (1) with no
//     apimachinery dependence.
//
// (3) kustomize-k8sdeps - A thin code layer that depends
//     on (vendors) apimachinery to provide thin implementations
//     to interfaces used in (2).
//
// The kubectl repo would then vendor from (2) only, and have
// a local implementation of (3).  With that in mind, it's clear
// that (3) doesn't have to be a repo; the kustomize version of
// the thin layer can live directly in (1).
//
// This package is the code in (3), meant for kustomize.

package k8sdeps