On-Demand Nodes

On-demand instances are individual, on-time instances created via the Operator API on request. This is separate from standard auto-scaling instances created by the Nstance Server reconciler.

All instances references a Group to derive its configuration. On-demand instances are additional instances beyond the group’s desired size and are not managed by the Nstance Server reconciler — they are not counted in reconciliation decisions and will not be automatically scaled down if the group size is reduced.

Pod-Triggered Provisioning

The Nstance Operator watches for Pods with the on-demand.nstance.dev/group annotation.

If found, it will create a new CAPI Machine resource, and looks for the following annotations to use for the NstanceMachine fields:

• groupRef: = on-demand.nstance.dev/group: the name of the Nstance Group to use for the on-demand node
• instanceType: = on-demand.nstance.dev/instance-type: the instance type to use for the on-demand node

Lifecycle

1. Pod created with on-demand.nstance.dev/group annotation
2. Operator creates CAPI Machine + NstanceMachine resources
3. Server creates instance, agent registers, node joins
4. Pod scheduler places Pod on new node

On-demand instances can be configured with a maximum age via server.expiry.ondemandAge to ensure temporary instances don’t persist indefinitely. See Instance Expiry for details.