autoscale-disk

#!/bin/bash
# 	Copyright 2015, Google, Inc.
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.

# Usage info
show_help() {
cat << EOF
Usage: ${0##*/} -d CLOUDDISK [-t THRESHOLD] [-f FACTOR] [-m MAX]
Checks the disk utilization of CLOUDDISK and if it is over the THRESHOLD
increase the disk size by multiplying current size by FACTOR as long as it
does not exceed MAX.
    -c              Check to make sure you have properly authorized service 
                    account. 
                    SUCCESS = display from gcloud compute disks list
                    FAILURE = ERROR - Insufficient Permission
    -h              Display this help and exit
    -d CLOUDDISK    The Google Cloud Disk name to check. This name can be seen
                    running 'gcloud compute disks list'
    -t THRESHOLD    The percentage (0-100) above which to resize the disk. 
                    DEFAULT 90
    -f FACTOR       The multiplier to resize the disk by. A 1GB disk with
                    a factor of 2 will be resized to 2GB. 
                    DEFAULT 2.
    -m MAX          The limit in GB beyond which we will not resize a disk. 
                    DEFAULT 6400GB.
Examples:
Run with defaults on a disk named 'storage' - 
    ${0##*/} -d storage

Check if the disk 'storage' is more than 50% usage, if so quadruple the disk 
to a limit of 1000GB 
    ${0##*/} -d storage - t 50 -f 4 -m 1000
    
EOF
}

check_perms() {
    /usr/local/bin/gcloud compute disks list

}

# Initialize our own variables:
THRESHOLD=90
FACTOR=2
MAX=64000
while getopts "d:t:m:f:hc" opt; do
    case "$opt" in
        h)
            show_help >&2
            exit
            ;;
        c)
            check_perms >&2
            exit
            ;;    
        d)  
            CLOUDDISK=$OPTARG
            ;;
        t)  
            THRESHOLD=$OPTARG
            ;;
        m)  
            MAX=$OPTARG
            ;;        
        f)  
            FACTOR=$OPTARG
            ;;
    esac
done
if [ "$CLOUDDISK" = "" ]
then
    echo "You must set a CLOUDDISK using -d option. Run ${0##*/} -h for more help. "
    exit
fi

# Get variables for scale parameters
LOCALDISK=`readlink -f /dev/disk/by-id/google-$CLOUDDISK`

# Get current usage in percentage expressed as a number between 1-100
tmp=`df $LOCALDISK | awk '{ print $5 }' | tail -n 1`
USAGE="${tmp//%}"

# Check to see if disk is over threshold. 
if [ $USAGE -lt $THRESHOLD ]
then
        echo "Disk is within threshold"
        exit
else
        echo "Disk is over threshold, attempting to resize"
fi

# Get Current size of disk
tmp2=`df -BG $LOCALDISK | awk '{ print $2 }' | tail -n 1`
CURRENTSIZE="${tmp2//G}"

# Compute next size of disk. 
PROPOSEDSIZE=$(( CURRENTSIZE * FACTOR ))
if [ $PROPOSEDSIZE -gt $MAX ]
then
        echo "Proposed disk size ($PROPOSEDSIZE)GB is higher than the max allowed ($MAX)GB."
        exit
else
        echo "Proposed disk size acceptable, attempting to resize"
fi

# RESIZE IT
ZONE=`/usr/local/bin/gcloud compute disks list $CLOUDDISK | awk '{ print $2 }' | tail -n 1`
/usr/local/bin/gcloud compute disks resize $CLOUDDISK --size "$PROPOSEDSIZE"GB --zone $ZONE --quiet

# Tell the OS that the disk has been resized.
sudo resize2fs /dev/disk/by-id/google-"$CLOUDDISK"