gcloud alpha compute instance-groups managed adopt-instances

NAME
gcloud alpha compute instance-groups managed adopt-instances - adopt instances into a regional managed instance group
SYNOPSIS
gcloud alpha compute instance-groups managed adopt-instances NAME --instances=INSTANCE,[INSTANCE,…] [--region=REGION] [GCLOUD_WIDE_FLAG …]
DESCRIPTION
(ALPHA) gcloud alpha compute instance-groups managed adopt-instances adopts one or more existing unmanaged instances into a regional managed instance group, thereby increasing the targetSize of the group.

Adopting an instance does not reboot or modify the underlying virtual machine instances, but adds the instances to the instance group and applies any target pools or backend services configured for the group.

Currently, adopting instances is only supported for regional managed instance groups.

POSITIONAL ARGUMENTS
NAME
Name of the managed instance group to operate on.
REQUIRED FLAGS
--instances=INSTANCE,[INSTANCE,…]
Names of instances to adopt.
OPTIONAL FLAGS
--region=REGION
Region of the managed instance group to operate on. If not specified, you might be prompted to select a region (interactive mode only).

To avoid prompting when this flag is omitted, you can set the compute/region property: 

gcloud config set compute/region REGION

A list of regions can be fetched by running: 

gcloud compute regions list

To unset the property, run: 

gcloud config unset compute/region

Alternatively, the region can be stored in the environment variable CLOUDSDK_COMPUTE_REGION.

GCLOUD WIDE FLAGS
These flags are available to all commands: --access-token-file, --account, --billing-project, --configuration, --flags-file, --flatten, --format, --help, --impersonate-service-account, --log-http, --project, --quiet, --trace-token, --user-output-enabled, --verbosity.

Run $ gcloud help for details.

NOTES
This command is currently in alpha and might change without notice. If this command fails with API permission errors despite specifying the correct project, you might be trying to access an API with an invitation-only early access allowlist. This variant is also available: 
gcloud beta compute instance-groups managed adopt-instances