Consuming reserved zonal resources

Customers can reserve Compute Engine instances in a specific zone to ensure resources are available for their workloads when needed. For more details on how to manage reservations, see Reserving Compute Engine zonal resources.

After creating reservations, you can create Google Kubernetes Engine (GKE) clusters and node pools to consume the reserved instances. GKE supports the same consumption modes as Compute Engine:

Before you begin

Before you start, make sure you have performed the following tasks:

Set up default gcloud settings using one of the following methods:

  • Using gcloud init, if you want to be walked through setting defaults.
  • Using gcloud config, to individually set your project ID, zone, and region.

Using gcloud init

If you receive the error One of [--zone, --region] must be supplied: Please specify location, complete this section.

  1. Run gcloud init and follow the directions:

    gcloud init

    If you are using SSH on a remote server, use the --console-only flag to prevent the command from launching a browser:

    gcloud init --console-only
  2. Follow the instructions to authorize gcloud to use your Google Cloud account.
  3. Create a new configuration or select an existing one.
  4. Choose a Google Cloud project.
  5. Choose a default Compute Engine zone.

Using gcloud config

  • Set your default project ID:
    gcloud config set project project-id
  • If you are working with zonal clusters, set your default compute zone:
    gcloud config set compute/zone compute-zone
  • If you are working with regional clusters, set your default compute region:
    gcloud config set compute/region compute-region
  • Update gcloud to the latest version:
    gcloud components update

Consuming reserved instances in GKE

When you create a cluster or node pool, you can indicate the reservation consumption mode by specifying the --reservation-affinity flag.

Consuming any matching reservations

To consume from any matching reservations automatically, set the reservation affinity flag to --reservation-affinity=any.

In the any reservation consumption mode, nodes first take capacity from any matching reservations in the same zone, and if that's insufficient, fulfill the rest from the general Compute Engine resource pool. See How reservations work for details on how Compute Engine matches reservations.

To create a reservation and instances to consume any reservation, perform the following steps:

  1. Create a reservation of three VM instances:

    gcloud compute reservations create RESERVATION_NAME \
        --machine-type=MACHINE_TYPE --vm-count=3
    

    Replace the following:

    • RESERVATION_NAME: the name of the reservation to create.
    • MACHINE_TYPE: the type of machine (name only) to use for the reservation. For example, n1-standard-2.
  2. Verify the reservation was created successfully:

    gcloud compute reservations describe RESERVATION_NAME
    

    Replace RESERVATION_NAME with the name of the reservation you just created.

  3. Create a cluster having one node to consume any matching reservation:

    gcloud container clusters create CLUSTER_NAME \
        --machine-type=MACHINE_TYPE --num-nodes=1 \
        --reservation-affinity=any
    

    Replace the following:

    • CLUSTER_NAME: the name of the cluster to create.
    • MACHINE_TYPE: the type of machine (name only) to use for the cluster. For example n1-standard-2.
  4. Create a node pool with three nodes to consume any matching reservation:

    gcloud container node-pools create NODEPOOL_NAME \
        --cluster CLUSTER_NAME --num-nodes=3 \
        --machine-type=MACHINE_TYPE --reservation-affinity=any
    

    Replace the following:

    • NODEPOOL_NAME: the name of the node pool to create.
    • CLUSTER_NAME: the name of the cluster you created earlier.
    • MACHINE_TYPE: the type of machine (name only) to use for the node pool. For example n1-standard-2.

The total number of nodes is four, which exceeds the capacity of the reservation. Three of the nodes consume the reservation while the last node takes capacity from the general Compute Engine resource pool.

Consuming a specific reservation

To consume a specific reservation, set the reservation affinity flag to --reservation-affinity=specific and provide the specific reservation name. In this mode, instances must take capacity from the specified reservation in the zone. The request fails if the reservation does not have sufficient capacity.

To create a reservation and instances to consume a specific reservation, perform the following steps:

  1. Create a specific reservation of three VM instances:

    gcloud compute reservations create RESERVATION_NAME \
        --machine-type=MACHINE_TYPE --vm-count=3 \
        --require-specific-reservation
    

    Replace the following:

    • RESERVATION_NAME: the name of the reservation to create.
    • MACHINE_TYPE: the type of machine (name only) to use for the reservation. For example, n1-standard-2.
  2. Create a cluster having one node to consume any matching reservation:

    gcloud container clusters create CLUSTER_NAME \
        --machine-type=MACHINE_TYPE --num-nodes=1 \
        --reservation-affinity=specific --reservation=RESERVATION_NAME
    

    Replace the following:

    • CLUSTER_NAME: the name of the cluster to create.
    • MACHINE_TYPE: the type of machine (name only) to use for the cluster. For example n1-standard-2.
    • RESERVATION_NAME: the name of the reservation to consume.
  3. Create a node pool with two nodes to consume any matching reservation:

    gcloud container node-pools create NODEPOOL_NAME \
        --cluster CLUSTER_NAME --num-nodes=2 \
        --machine-type=MACHINE_TYPE \
        --reservation-affinity=specific --reservation=RESERVATION_NAME
    

    Replace the following:

    • NODEPOOL_NAME: the name of the node pool to create.
    • CLUSTER_NAME: the name of the cluster you created earlier.
    • MACHINE_TYPE: the type of machine (name only) to use for the node pool. For example n1-standard-2.
    • RESERVATION_NAME: the name of the reservation to consume.

Additional considerations for consuming from a specific reservation

When a node pool is created with specific reservation affinity, including default node pools during cluster creation, its size is limited to the capacity of the specific reservation over the node pool's entire lifetime. This affects the following GKE features:

  • Cluster with multiple zones: In regional or multi-zonal clusters, nodes of a node pool can span across multiple zones. Since reservations are single-zonal, multiple reservations are needed. To create a node pool consuming specific reservation in these clusters, you must create a specific reservation with exactly the same name and machine properties in each zone of the node pool.
  • Cluster autoscaling/surge upgrade: If you don't have extra capacity in the specific reservation, surge upgrades or auto-scaling of the node pool might fail because both require creating extra instances. To resolve this, you can change the size of the reservation, or free up some of its bounded resources.

Creating nodes without consuming reservations

To explicitly avoid consuming resources from any reservations, set the affinity to --reservation-affinity=none.

  1. Create a cluster to consume any matching reservation:

    gcloud container clusters create CLUSTER_NAME --reservation-affinity=none
    

    Replace CLUSTER_NAME with the name of the cluster to create.

  2. Create a node pool to consume any matching reservation:

    gcloud container node-pools create NODEPOOL_NAME \
        --cluster CLUSTER_NAME \
        --reservation-affinity=none
    

    Replace the following:

    • NODEPOOL_NAME: the name of the node pool to create.
    • CLUSTER_NAME: the name of the cluster you created earlier.

Cleaning up

To avoid incurring charges to your Google Cloud account for the resources used in this page:

  1. Delete the clusters you created by running the following command for each of the clusters:

    gcloud container clusters delete CLUSTER_NAME
    
  2. Delete the reservations you created by running the following command for each of the reservations:

    gcloud compute reservations delete RESERVATION_NAME
    

What's next