Clone GCP instance using gcloud cli. google cloud, clone instance, create similar, programatically, script. --- creates a snapshot and an instance template from an instance, then creates new instances using them

clone.sh

#!/usr/bin/env bash


if [ $# -lt 2 ]
  then
  cat << EOF
usage: `basename "$0"` [-g <group-name> ] <source-instance-name>  <cloned-instance-name1> [<cloned-instance-name2>... N]
Clone the source instance in the same region N+1 times and possbliy put all cones into a new unmanaged instance group

-g <group name>(optional)- use this flag to put all newly created instnaces into
                           a new unmanged instance group named <group-name>

<source-instance-name> -   the name of the instance to be cloned, followed by the clones names

EOF
exit 0
fi


# exit when any command fails
set -e

# keep track of the last executed command
trap 'last_command=$current_command; current_command=$BASH_COMMAND' DEBUG
# echo an error message before exiting
trap 'echo "\"${last_command}\" command filed with exit code $?."' EXIT
export LC_CTYPE=C
RANDGUID=`cat /dev/urandom | tr -dc 'a-z0-9' | fold -w 10 | head -n 1`


if [ $1 = "-g" ]
then
  GROUP_NAME=$2
  shift 2
else
  GROUP_NAME=
fi

INSTANCE_NAME=$1
shift 1
CLONE_NAMES=$@

INSTANCE_INFO=`gcloud compute instances list --filter="name=$INSTANCE_NAME" | tail -n 1`
INSTANCE_ZONE=`echo $INSTANCE_INFO | awk '{print $2}'`
INSTANCE_REGION=`echo $INSTANCE_ZONE| cut -d'-' -f -2`
INSTANCE_STATUS=`echo $INSTANCE_INFO | awk '{print $NF}'`

INSTANCE_DISK_INFO=`gcloud compute disks list --filter="name=$INSTANCE_NAME"| tail -n 1`
INSTANCE_DISK_SIZE=`echo $INSTANCE_DISK_INFO | awk '{print $4}'`
INSTANCE_DISK_TYPE=`echo $INSTANCE_DISK_INFO | awk '{print $5}'`

echo - Instance name:$INSTANCE_NAME, Zone:$INSTANCE_ZONE \(Region:$INSTANCE_REGION\), Status:$INSTANCE_STATUS

echo - Creating an instance template...
if gcloud compute disks describe $INSTANCE_NAME --zone $INSTANCE_ZONE | grep sourceImage
then
  gcloud compute instance-templates create $INSTANCE_NAME-$RANDGUID --source-instance $INSTANCE_NAME --source-instance-zone $INSTANCE_ZONE
else
  # a cloned machine does not have a source image and throws here unless this workaround is used
  gcloud compute instance-templates create $INSTANCE_NAME-$RANDGUID --source-instance $INSTANCE_NAME --source-instance-zone $INSTANCE_ZONE \
    --configure-disk=device-name=$INSTANCE_NAME,instantiate-from=custom-image,auto-delete=true,custom-image=projects/debian-cloud/global/images/debian-9-stretch-v20191210
fi

echo - Cloning boot disk \(NOTE: only the boot disk is cloned into new instances!\)...
gcloud compute disks snapshot $INSTANCE_NAME --description 'Cloned by script' --zone $INSTANCE_ZONE --snapshot-names $INSTANCE_NAME-$RANDGUID --storage-location $INSTANCE_REGION


for CLONE_NAME in $CLONE_NAMES; do
    echo - Creating $CLONE_NAME...
    gcloud compute instances create $CLONE_NAME --source-instance-template $INSTANCE_NAME-$RANDGUID \
      --source-snapshot $INSTANCE_NAME-$RANDGUID --boot-disk-size $INSTANCE_DISK_SIZE \
      --boot-disk-type $INSTANCE_DISK_TYPE --boot-disk-device-name $CLONE_NAME \
      --zone $INSTANCE_ZONE --async 
done

sleep 3
if [ ! -z "$GROUP_NAME" ]
  then
  echo - Adding newly created instances to the unmanaged group: $GROUP_NAME...
  gcloud compute instance-groups unmanaged create "$GROUP_NAME" --zone $INSTANCE_ZONE
  COMMA_SEP_INSTS=${CLONE_NAMES// /,}
  gcloud compute instance-groups unmanaged add-instances "$GROUP_NAME" --instances $COMMA_SEP_INSTS --zone $INSTANCE_ZONE
fi

echo - Waiting for all instnaces to be ready
while `gcloud compute instances list --filter "name=($CLONE_NAMES)" | grep -q STAGING`
do
  printf '.'
  sleep 5
done
echo ...Ready!

echo - Cleaning up...
gcloud compute instance-templates delete --quiet $INSTANCE_NAME-$RANDGUID
gcloud compute snapshots delete --quiet $INSTANCE_NAME-$RANDGUID