Introduce new kubernetes-novolume mode

[nikola-jokic]

As part of the effort to remove volumes on the hook side, we are introducing a new mode. The purpose is to ship the new feature, but also keep the old way the hook worked. The new way of not having volumes is risky in a sense that we are not certain they are covering 100% of the cases, and will impose new limitations while eliminating some of the old limitations. Therefore, we are shipping a new mode so you can quickly revert the change and use the normal kubernetes mode while we are fixing the hook.

The intention is to ship the new hook as a normal "kubernetes" mode as soon as we are certain it covers most of the cases.

Related work: actions/runner-container-hooks#244

[Copilot]

Pull Request Overview

This PR introduces a new kubernetes-novolume container mode as an alternative to the existing kubernetes mode, designed to eliminate volume dependencies while maintaining compatibility with the current approach. The change provides a safer rollout path for volume-less runners while allowing quick fallback to the original implementation.

• Adds kubernetes-novolume as a third container mode option alongside dind and kubernetes
• Implements specialized template handling for the new mode with different environment variables and no volume mounts
• Updates RBAC permissions to exclude job-related permissions for the novolume mode

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
values.yaml	Updates documentation to include the new kubernetes-novolume mode option
template_test.go	Adds comprehensive test coverage for the new kubernetes-novolume mode including RBAC, TLS, and template rendering
kube_mode_serviceaccount.yaml	Extends service account creation condition to include kubernetes-novolume mode
kube_mode_role_binding.yaml	Extends role binding creation condition to include kubernetes-novolume mode
kube_mode_role.yaml	Extends role creation condition and excludes job permissions for kubernetes-novolume mode
autoscalingrunnerset.yaml	Adds template selection logic and cleanup annotations for kubernetes-novolume mode
_helpers.tpl	Implements new template helper for kubernetes-novolume mode container configuration

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}