I’ve stolen the example from here but i’ve made my own adjustments

1. Create an Amazon IAM user for snapshotting and save the credentials file. ( You’ll need them to use the amazon cli api , it comes in csv format)
Create an Amazon IAM Group for snapshot permissions
add a “Custom Policy” and paste the code block below
Example IAM Policy:

{
  "Statement": [
    {
      "Action": [
        "ec2:DescribeVolumes",
        "ec2:CreateSnapshot",
        "ec2:DeleteSnapshot",
        "ec2:DescribeSnapshotAttribute",
        "ec2:DescribeSnapshots",
        "ec2:ModifySnapshotAttribute",
        "ec2:ResetSnapshotAttribute"
      ],
      "Effect": "Allow",
      "Resource": [
        "*"
      ]
    }
  ]
}

2. Install the Amazon CLI Tools

$ wget http://s3.amazonaws.com/ec2-downloads/ec2-api-tools.zip
$ unzip ec2-api-tools.zip
$ mv ec2-api-tools /opt
$ ln -s /opt/ec2-api-tools /opt/aws

3. Install the below script in cron on your snapshot interval and change the “Constants” and also plugin your AWS Keys
Script Below

#!/bin/bash
# EBS Snapshot volume script
# Constants - You'll want to edit these
JAVA_HOME="/usr"
EC2_HOME="/opt/aws"
ec2_bin="/opt/aws/bin"
export EC2_HOME
export JAVA_HOME
LOGFILE='/var/log/aws_snapshot.log'
TMPFILE='/tmp/snap_info.txt'

VOLTMPFILE='/tmp/volume_info.txt'

# Retention in days
RETENTION="7"

# AWS ACCESS INFO
access_key='SOMEACCESSKEY'
secret_key='SOMESECRETKEY'
instance_id=`wget -q -O- http://169.254.169.254/latest/meta-data/instance-id`

# Dates
datecheck_7d=`date +%Y-%m-%d --date "$RETENTION days ago"`
datecheck_s_7d=`date --date="$datecheck_7d" +%s`
datenow=`date +%Y-%m-%d-%H:%M:%S`

# Add entry in logfile for run begin
echo "${datenow} ======= BEGIN SNAPSHOT SCRIPT =========" 2>&1 >> $LOGFILE
# Get all volume info and copy to temp file
$ec2_bin/ec2-describe-volumes -O $access_key -W $secret_key  --filter "attachment.instance-id=$instance_id" > $VOLTMPFILE 2>&1

# Get all snapshot info
$ec2_bin/ec2-describe-snapshots -O $access_key -W $secret_key | grep "$instance_id" > $TMPFILE 2>&1

# Loop to remove any snapshots older than 7 days
for obj0 in $(cat $TMPFILE | awk '{print $5}')
do
        snapshot_name=`cat $TMPFILE | grep "$obj0" | awk '{print $2}'`
        datecheck_old=`cat $TMPFILE | grep "$snapshot_name" | awk '{print $5}' | awk -F "T" '{print $1}'`
        datecheck_s_old=`date --date="$datecheck_old" +%s`

        # Check if snapshot is older than retention days
        if (( $datecheck_s_old <= $datecheck_s_7d ));
        then
                echo "deleting snapshot $snapshot_name ... older than $RETENTION days" 2>&1 >> $LOGFILE
                $ec2_bin/ec2-delete-snapshot -O $access_key -W $secret_key $snapshot_name
        else
                echo "not deleting snapshot $snapshot_name ... not older than $RETENTION days" 2>&1 >> $LOGFILE
        fi
done

# Create snapshot
for volume in $(cat $VOLTMPFILE | grep "VOLUME" | awk '{print $2}')
do
        # Description cannot have spaces
        description="instance-id:${instance_id}_vol-id:${volume}_`hostname`_backup-`date +%Y-%m-%d`"
        echo "Creating Snapshot for the volume: $volume with description: $description" 2>&1 >> $LOGFILE
        $ec2_bin/ec2-create-snapshot -O $access_key -W $secret_key -d "$description" $volume 2>&1 >> $LOGFILE
done