Scaling based on CPU utilization

Console

1. In the console, go to the Instance groups page.

   Go to Instance groups

2. If you have an instance group, click the name of the instance group, and then click Edit. On the edit instance group page, do the following:

   1. Click Group size & autosclaing to expand the section.
   2. Click Configure autoscaling.

3. If you don't have an instance group, click Create instance group and do the following:

   1. In the Name field, specify a name for the group.
   2. In the Instance template list, select a template.

   3. In the Location section, depending on whether you're creating a zonal or regional MIG, choose an option as follows:

      • For a zonal MIG, select Single zone, and then select a region and a zone.
      • For a regional MIG, select Multiple zones, and then select a region and zones.

4. In the Autoscaling section, a CPU utilization autoscaling signal is added by default. You can either use the default values for the signal or do the following:

   1. Specify the minimum and the maximum numbers of instances that you want the autoscaler to create in this group.

   2. To edit the target CPU utilization, click the CPU utilization signal to expand the section and specify the percentage.

      1. Under Predictive autoscaling, select Off. To learn more about predictive autoscaling, and whether it is suitable for your workload, see Scaling based on predictions.

   3. Click Done.

5. You can use the Initialization period to tell the autoscaler how long it takes for your application to initialize. Specifying an accurate initialization period improves autoscaler decisions. For example, when scaling out, the autoscaler ignores data from VMs that are still initializing because those VMs might not yet represent normal usage of your application. The default initialization period is 60 seconds.

6. Click Save.

gcloud

Use the set-autoscaling sub-command to enable autoscaling for a managed instance group. For example, the following command creates an autoscaler that has a target CPU utilization of 60%. Along with the --target-cpu-utilization parameter, the --max-num-replicas parameter is also required when creating an autoscaler:

gcloud compute instance-groups managed set-autoscaling example-managed-instance-group \
    --max-num-replicas 20 \
    --target-cpu-utilization 0.60 \
    --cool-down-period 90 \
    --stabilization-period 240

Optionally, set the following flags to control autoscaling:

• You can use the --cool-down-period flag to set the initialization period, which tells the autoscaler how long it takes for your application to initialize. Specifying an accurate initialization period improves autoscaler decisions. For example, when scaling out, the autoscaler ignores data from VMs that are still initializing because those VMs might not yet represent normal usage of your application. The default initialization period is 60 seconds.
• You can use the --stabilization-period flag to set the stabilization period, which determines the duration for your MIG to scale in. A shorter stabilization period indicates quicker VM deletion to scale in. The value must be between `0` seconds and `3600` seconds. The default value is `600` seconds. For more information, see Best practices for stabilization period.

Optionally, you can enable predictive autoscaling to scale out ahead of predicted load. To learn whether predictive autoscaling is suitable for your workload, see Scaling based on predictions.

You can verify that autoscaling is successfully enabled by using the instance-groups managed describe sub-command, which describes the corresponding managed instance group and provides information about any autoscaling features for that instance group:

gcloud compute instance-groups managed describe example-managed-instance-group

For a list of available gcloud commands and flags, see the gcloud reference.

REST

To create an autoscaler, use the autoscalers.insert method for a zonal MIG or the regionAutoscalers.insert method for a regional MIG.

The following example creates an autoscaler for a zonal MIG:

POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/autoscalers

Your request body must contain the name, target, and autoscalingPolicy fields. autoscalingPolicy must define cpuUtilization and maxNumReplicas.

Optionally, set the following fields to control autoscaling:

• You can use the coolDownPeriodSec field to set the initialization period, which tells the autoscaler how long it takes for your application to initialize. Specifying an accurate initialization period improves autoscaler decisions. For example, when scaling out, the autoscaler ignores data from VMs that are still initializing because those VMs might not yet represent normal usage of your application. The default initialization period is 60 seconds.
• You can use the stabilizationPeriodSec field to set the stabilization period, which determines the duration for your MIG to scale in. A shorter stabilization period indicates quicker VM deletion to scale in. The value must be between `0` seconds and `3600` seconds. The default value is `600` seconds. For more information, see Best practices for stabilization period.

Optionally, you can enable predictive autoscaling to scale out ahead of predicted load. To learn whether predictive autoscaling is suitable for your workload, see Scaling based on predictions.

{
  "name": "example-autoscaler",
  "target": "https://www.googleapis.com/compute/v1/projects/myproject/zones/us-central1-f/instanceGroupManagers/example-managed-instance-group",
  "autoscalingPolicy": {
    "maxNumReplicas": 10,
    "cpuUtilization": {
      "utilizationTarget": 0.6
    },
    "coolDownPeriodSec": 90,
    "stabilizationPeriodSec": 240
  }
}