H4HIP: Move pkgs to be internal

hips/hip-XXXX.md

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+---
+hip: 9999
+title: "Moving non-Action packages to be internal"
+authors: [ "George Jenkins <[email protected]>" ]
+created: "2020-08-13"
+type: "feature"
+status: "draft"
+helm-version: "4"
+---
+
+## Abstract
+
+This HIP proposes moving non-Action packages which are unlikely to be used by Helm SDK clients to be internal/non-public.
+
+## Motivation
+
+A significant awkwardness with Helm 3, was that all public packages had to remain API compatible.
+And a large portion of Heln's implementation code was directly exposed as public packages.
+Having no seperatation between API interface and implementation frequently made it difficult to introduce changes to Helm's codebase.
+Even if public APIs were unlikely to be used by external SDK users.
+
+## Rationale
+
+Moving packages to be internal should allow more flexibility for Helm to make changes in the the future.
+Functionality that is desired to be exposed to public can be exposed via public API specific wrappers.
+Reducing the friction between improving/extending/modifying/extending Helm's functionality.
+And providing stable API guarentees.
+
+## Specification
+
+The following packages could be moved to be `internal`:
+
+```
+pkg/chart
+pkg/chartrelease
+pkg/chartutil
+pkg/engine
+pkg/gates
+pkg/ignore
+pkg/kube
+pkg/kube/fake
+pkg/lint
+pkg/lint/rules
+pkg/lint/support
+pkg/plugin
+pkg/plugin/cache
+pkg/plugin/installer
+pkg/postrender
+pkg/provenance
+pkg/pusher
+pkg/registry
+pkg/release // Some external usage, replacement public API creation should be examined
+pkg/releaseutil
+pkg/repo
+pkg/repo/repotest
+pkg/storage
+pkg/storage/driver
+pkg/strvals
+pkg/time
+pkg/uploader
+```
+
+The following packages should remain as public facing packages:
+```
+pkg/action
+pkg/cli
+pkg/getter // Implementations should be moved to be internal
+pkg/helmpath
+pkg/chart/loader
+pkg/downloader
+```
+
+## Backwards compatibility
+
+From a search in public github, the list to move to internal seems to either be minimally (indicating a limited pulic API could be created, or public use deprecated) or unused.
+As such, moving these packages to internal will likely have minimal/insignificant impact to the community.
+If required, packages could easily be returned to being public should the community request even once Helm 4 is released.
+
+## Rejected ideas
+
+Moving packages which provide core SDK functionality, such as `pkg/action`.
+Or packages which seem to have significant external usage.