Reservation Affinity

spec.reservationAffinity on GCPManagedMachinePools (or GCPManagedMachinePoolTemplates) controls the behaviour that GKE takes towards any compute reservations that you want to use with GKE node pools. For further information about this feature see Google’s Documentation

Reservations allow you to reserve compute capacity with a high degree of confidence, so that you can have a higher degree of certainty that your cluster has node capacity when required.

Note: spec.reservationAffinity is immutable and can only be set at creation. Therefore if it needs to be changed you must create a new pool to do so.

Configuring Reservation Affinity

To configure Reservation Affinity, set the reservationAffinity key on GCPManagedMachinePool as below:

apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
kind: GCPManagedMachinePool
metadata:
  name: my-nodepool
spec:
  reservationAffinity:
    consumeReservationType: "NO_RESERVATION"

There are four values that consumeReservationType can be set to, which each induce different behavior:

• NO_RESERVATION - Explicitly do not take capacity from any reservations, instead draw it all from the general pool
• ANY_RESERVATION - Take capacity from any reservation that is available
• ANY_RESERVATION_THEN_FAIL - Take capacity from any reservation but fail if there is insufficient capacity in the reservations
• SPECIFIC_RESERVATION - Take capacity from a specific named reservation (see below)

SPECIFIC_RESERVATION is special because it requires two other configuration settings key and values, as can be seen below

apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
kind: GCPManagedMachinePool
metadata:
  name: my-nodepool
spec:
  reservationAffinity:
    consumeReservationType: "SPECIFIC_RESERVATION"
    key: "compute.googleapis.com/reservation-name"
    values:
      - "my-reservation"

key is the property and values is the set of values that need to match for capacity to be consumed.

key must be exactly compute.googleapis.com/reservation-name and values must list the names of reservations. If you set these values for any other consumeReservationType you will get a validation error.