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User guide: pause and resume (spec.powerState: Paused)

Suspend a running Machine's guest CPUs without tearing anything down -- Kairon's equivalent of virtctl pause/unpause. Distinct from Stopped (which deletes the FluxVM runtime entirely, freeing its RAM) and from guest quiesce (which freezes the guest's own filesystem I/O via qemu-guest-agent, not its CPUs, and needs guest cooperation).

What this does​

apiVersion: kairon.zyvor.dev/v1alpha1
kind: Machine
metadata: {name: db}
spec:
  powerState: Paused   # was Running
  # ... unchanged otherwise

Or via kaironctl pause db / kaironctl resume db (kubectl kairon pause db works identically), or the dashboard's Pause/Resume buttons.

Pausing calls FluxVM's real QMP stop (or the Cloud Hypervisor/ Firecracker equivalent -- backend-agnostic, unlike CPU/memory hotplug's QEMU-only restriction) to suspend guest CPU execution. RAM, device state, and network attachment all stay fully resident and unchanged -- resuming (spec.powerState: Running, kaironctl resume, or the dashboard button) continues exactly where the guest left off, with no boot, no re-attach, nothing lost. status.phase reports Paused while suspended.

Real limits today (first cut)​

  • Requires an existing runtime. Setting powerState: Paused on a Machine that's never been realized against FluxVM (no prior Running state) doesn't create one paused-from-the-start -- status.phase stays Pending with a clear message instead. Set powerState: Running first, let it actually start, then pause it.
  • A Paused Machine still counts against the scheduler's per-node capacity, the same as Running -- unlike Stopped (which tears the runtime down and genuinely frees the node), a paused VMM process and its resident RAM are still there. Don't expect pausing a Machine to make room for another one on the same node.
  • No timeout or auto-resume. A Machine can stay Paused indefinitely; nothing here ever resumes it automatically.
  • Interaction with migration/hotplug is untested. Pausing a Machine mid-migration, or attempting spec.resources hotplug while paused, is real FluxVM/QMP behavior this guide doesn't make any claims about -- treat it as unsupported until verified, not silently safe.
  • No admission-time guard against pausing a Machine mid-migration -- spec.powerState and MachineMigration are reconciled independently; changing one while the other is mid-flight is between you and FluxVM's own QMP semantics, not something Kairon checks first.