> ## Documentation Index
> Fetch the complete documentation index at: https://arklowdocs.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Google Cloud managed instance groups

Arklow can change a Google Cloud managed instance group through its autoscaler or through the group's target size. Choose the mode that matches the controller already responsible for the group.

<Columns cols={2}>
  <Card title="Autoscaler floor" icon="arrows-up-down" href="/resources/scale-targets/gcp/autoscaler">
    Adjust the range available to an existing GCP autoscaler.
  </Card>

  <Card title="Desired count" icon="hashtag" href="/resources/scale-targets/gcp/desired">
    Resize a managed instance group to a concrete target size.
  </Card>
</Columns>

## Shared configuration

| Field                      | Value                                                                           |
| -------------------------- | ------------------------------------------------------------------------------- |
| **Project**                | The Google Cloud project that owns the group.                                   |
| **Location type**          | **Zone** for a zonal group or **Region** for a regional group.                  |
| **Location**               | A zone such as `us-central1-a` or a region such as `us-central1`.               |
| **Instance group manager** | The managed instance group name.                                                |
| **Credential**             | A [GCP Service Account credential](/resources/credentials/gcp/service-account). |

Arklow reads the group's target size, status, and current instance actions. Pending actions keep the target in a converging state until Google Cloud finishes the change.

## Mode selection

Use **GCP managed instance group** when the group has a Google Cloud autoscaler. Arklow changes the autoscaler's minimum and maximum, and the autoscaler remains responsible for the live count.

Use **GCP managed instance group (manual)** when the group is resized directly. Arklow requests a concrete target size within the target's envelope.