feat(release): publish Helm chart to OCI repo on release

[Vedansh074]

What this PR does

Right now the Nutanix CCM Helm chart is published from a separate place, so its
version drifts from the CCM image and releasing it is a manual, out-of-band step.
This PR brings the chart into this repo and makes our existing release workflow
publish it automatically — so every time we tag a CCM release, a matching Helm
chart is pushed to the same GHCR location we already use.

In short: tag vX.Y.Z → the workflow builds the image and ships
ghcr.io/nutanix-cloud-native/chart/nutanix-cloud-provider:X.Y.Z alongside it.

Why it's built this way

A couple of decisions worth calling out for review:

• The chart is intentionally a copy of the currently published 0.5.6 chart.
  I pulled the live chart from GHCR and matched it template-for-template and
  value-for-value, so existing users' values.yaml files and --set flags keep
  working unchanged. The only differences are in Chart.yaml (see below). If you
  want to diff it against the published one, everything except Chart.yaml is
  byte-identical.

• We publish with plain helm package + helm push, not
  chart-releaser-action. The chart is consumed as an OCI artifact, and
  chart-releaser-action is really for GitHub-Pages chart repos — it would also
  create its own GitHub Releases and collide with the release this workflow
  already produces. Plain package/push is simpler and matches how the chart is
  actually distributed.

• Version handling. The chart version uses the tag without the leading v
  (e.g. 0.6.5, because Helm chart versions must be plain semver), while
  appVersion keeps the v (e.g. v0.6.5) so the chart's default image tag
  lines up with the image this same job builds and pushes.

Changes

New chart — charts/nutanix-cloud-provider/

• Deployment, ConfigMap, RBAC (SA + ClusterRole + binding), and an optional
  credentials Secret, plus helpers/NOTES — mirrored from the published chart.
• Chart.yaml: version/appVersion are 0.0.0 placeholders that the release
  workflow overwrites from the tag; I also dropped the version-specific
  artifacthub.io/changes annotation so it doesn't go stale every release.

Release workflow — .github/workflows/release.yaml

• Added packages: write (+ contents: write) to the build_release job so it
  can push to GHCR.
• Added steps to set up Helm, package the chart with the tag-derived version, and
  push it to oci://ghcr.io/nutanix-cloud-native/chart.

Docs

• charts/.../README.md: fixed install/upgrade instructions to use the OCI
  registry (they previously pointed at the old nutanix.github.io/helm
  GitHub-Pages repo), cleaned up leftover "Nutanix-CSI" copy-paste text, corrected
  a default value, and made the Contributing/Issues links absolute (the relative
  ../../issues link was broken from the chart's directory depth).
• Root README.md: added an Installation section documenting the Helm/OCI install
  method, linking to the chart README.

How I tested it

• helm lint passes.
• Chart renders cleanly and the generated nutanix_config.json is valid JSON.
• Confirmed the chart is byte-for-byte identical to the published 0.5.6 chart
  except for the intentional Chart.yaml changes.
• Simulated a v0.6.5 release locally: produces nutanix-cloud-provider-0.6.5.tgz,
  the rendered image resolves to controller:v0.6.5, and the push target is
  ghcr.io/nutanix-cloud-native/chart/nutanix-cloud-provider:0.6.5.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.75%. Comparing base (48ff296) to head (37bba9d).
⚠️ Report is 23 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #253      +/-   ##
==========================================
- Coverage   79.64%   77.75%   -1.89%     
==========================================
  Files           8        8              
  Lines         393      517     +124     
==========================================
+ Hits          313      402      +89     
- Misses         80      115      +35     

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[thunderboltsid]

@Vedansh074 this would also have to be backported to v0.5.x, v0.6.x, and v0.7.x branches

[Copilot]

Pull request overview

Adds the Nutanix CCM Helm chart to this repository and extends the existing release workflow so a Git tag release publishes both the controller image and a matching Helm chart to GHCR as an OCI artifact.

Changes:

• Introduces charts/nutanix-cloud-provider/ (templates, values, docs) for the CCM Helm chart.
• Updates .github/workflows/release.yaml to lint, package, and push the chart to ghcr.io/... on tag releases.
• Updates root and chart docs to describe OCI-based Helm install/upgrade.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 14 comments.

Show a summary per file

File	Description
README.md	Adds OCI Helm installation instructions and links to the chart README.
.github/workflows/release.yaml	Adds Helm/chart-testing setup, linting, packaging, and OCI push to GHCR during release.
charts/nutanix-cloud-provider/Chart.yaml	Adds chart metadata and placeholder version/appVersion for release-time override.
charts/nutanix-cloud-provider/README.md	Documents OCI install/upgrade/uninstall and configuration values.
charts/nutanix-cloud-provider/values.yaml	Defines default chart values for Prism Central, image, scheduling, etc.
charts/nutanix-cloud-provider/.helmignore	Adds standard Helm packaging ignore patterns.
charts/nutanix-cloud-provider/templates/_helpers.tpl	Adds helper template definitions (labels/names).
charts/nutanix-cloud-provider/templates/cloud-provider-nutanix-deployment.yaml	Adds the CCM Deployment template.
charts/nutanix-cloud-provider/templates/cm.yaml	Adds ConfigMap templates including generated nutanix_config.json and CA bundle ConfigMap.
charts/nutanix-cloud-provider/templates/secret.yaml	Adds optional credentials Secret template.
charts/nutanix-cloud-provider/templates/rbac.yaml	Adds ServiceAccount, ClusterRole, and ClusterRoleBinding templates.
charts/nutanix-cloud-provider/templates/NOTES.txt	Adds post-install Helm notes output.

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[Vedansh074]

💚 All backports created successfully

Status	Branch	Result
✅	release-v0.6

Questions ?

Please refer to the Backport tool documentation

[Vedansh074]

💚 All backports created successfully

Status	Branch	Result
✅	release-v0.5

Questions ?

Please refer to the Backport tool documentation