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ebs-snapshot.sh
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#!/bin/bash
export PATH=$PATH:/usr/local/bin/:/usr/bin
# Safety feature: exit script if error is returned, or if variables not set.
# Exit if a pipeline results in an error.
set -ue
set -o pipefail
## Automatic EBS Volume Snapshot Creation & Clean-Up Script
#
# Written by Casey Labs Inc. (https://www.caseylabs.com)
# Casey Labs - Contact us for all your Amazon Web Services Consulting needs!
#
# Additonal credits: Log function by Alan Franzoni; Pre-req check by Colin Johnson
#
# PURPOSE: This Bash script can be used to take automatic snapshots of your Linux EC2 instance. Script process:
# - Determine the instance ID of the EC2 server on which the script runs
# - Gather a list of all volume IDs attached to that instance
# - Take a snapshot of each attached volume
# - The script will then delete all associated snapshots taken by the script that are older than 7 days
#
# DISCLAIMER: Hey, this script deletes snapshots (though only the ones that it creates)!
# Make sure that you undestand how the script works. No responsibility accepted in event of accidental data loss.
#
## Requirements ##
## 1) IAM USER:
#
# This script requires that a new IAM user be created in the IAM section of AWS.
# Here is a sample IAM policy for AWS permissions that this new user will require:
#
# {
# "Version": "2012-10-17",
# "Statement": [
# {
# "Sid": "Stmt1426256275000",
# "Effect": "Allow",
# "Action": [
# "ec2:CreateSnapshot",
# "ec2:CreateTags",
# "ec2:DeleteSnapshot",
# "ec2:DescribeSnapshotAttribute",
# "ec2:DescribeSnapshots",
# "ec2:DescribeVolumeAttribute",
# "ec2:DescribeVolumes"
# ],
# "Resource": [
# "*"
# ]
# }
# ]
# }
## 2) AWS CLI:
#
# This script requires the AWS CLI tools to be installed.
# Read more about AWS CLI at: https://aws.amazon.com/cli/
#
# Linux install instructions for AWS CLI:
# ASSUMPTION: these commands are ran as the ROOT user.
#
# - Install Python pip (e.g. yum install python-pip or apt-get install python-pip)
# - Then run: pip install awscli
#
# Configure AWS CLI by running this command:
# aws configure
#
# [NOTE: if you have an IAM Role Setup for your instance to use the IAM policy listed above, you can skip the aws configure step.]
#
# Access Key & Secret Access Key: enter in the credentials generated above for the new IAM user
# Region Name: the region that this instance is currently in (e.g. us-east-1, us-west-1, etc)
# Output Format: enter "text"
## 3) SCRIPT INSTALLATION:
#
# Copy this script to /opt/aws/ebs-snapshot.sh
# And make it exectuable: chmod +x /opt/aws/ebs-snapshot.sh
#
# Then setup a crontab job for nightly backups:
# (You will have to specify the location of the AWS CLI Config file)
#
# AWS_CONFIG_FILE="/root/.aws/config"
# 00 06 * * * root /opt/aws/ebs-snapshot.sh
## Variable Declartions ##
# Get Instance Details
instance_id=$(wget -q -O- http://169.254.169.254/latest/meta-data/instance-id)
region=$(wget -q -O- http://169.254.169.254/latest/meta-data/placement/availability-zone | sed -e 's/\([1-9]\).$/\1/g')
# Set Logging Options
logfile="/var/log/ebs-snapshot.log"
logfile_max_lines="5000"
# How many days do you wish to retain backups for? Default: 7 days
retention_days="7"
retention_date_in_seconds=$(date +%s --date "$retention_days days ago")
## Function Declarations ##
# Function: Setup logfile and redirect stdout/stderr.
log_setup() {
# Check if logfile exists and is writable.
( [ -e "$logfile" ] || touch "$logfile" ) && [ ! -w "$logfile" ] && echo "ERROR: Cannot write to $logfile. Check permissions or sudo access." && exit 1
tmplog=$(tail -n $logfile_max_lines $logfile 2>/dev/null) && echo "${tmplog}" > $logfile
exec > >(tee -a $logfile)
exec 2>&1
}
# Function: Log an event.
log() {
echo "[$(date +"%Y-%m-%d"+"%T")]: $*"
}
# Function: Confirm that the AWS CLI and related tools are installed.
prerequisite_check() {
for prerequisite in aws wget; do
hash $prerequisite &> /dev/null
if [[ $? == 1 ]]; then
echo "In order to use this script, the executable \"$prerequisite\" must be installed." 1>&2; exit 70
fi
done
}
# Function: Snapshot all volumes attached to this instance.
snapshot_volumes() {
for volume_id in $volume_list; do
log "Volume ID is $volume_id"
# Get the attched device name to add to the description so we can easily tell which volume this is.
device_name=$(aws ec2 describe-volumes --output=text --volume-ids $volume_id --query 'Volumes[0].{Devices:Attachments[0].Device}')
# Take a snapshot of the current volume, and capture the resulting snapshot ID
snapshot_description="$(hostname)-$device_name-backup-$(date +%Y-%m-%d)"
snapshot_id=$(aws ec2 create-snapshot --region $region --output=text --description $snapshot_description --volume-id $volume_id --query SnapshotId)
log "New snapshot is $snapshot_id"
# Add a "CreatedBy:AutomatedBackup" tag to the resulting snapshot.
# Why? Because we only want to purge snapshots taken by the script later, and not delete snapshots manually taken.
aws ec2 create-tags --region $region --resource $snapshot_id --tags Key=CreatedBy,Value=AutomatedBackup
done
}
# Function: Cleanup all snapshots associated with this instance that are older than $retention_days
cleanup_snapshots() {
for volume_id in $volume_list; do
snapshot_list=$(aws ec2 describe-snapshots --region $region --output=text --filters "Name=volume-id,Values=$volume_id" "Name=tag:CreatedBy,Values=AutomatedBackup" --query Snapshots[].SnapshotId)
for snapshot in $snapshot_list; do
log "Checking $snapshot..."
# Check age of snapshot
snapshot_date=$(aws ec2 describe-snapshots --region $region --output=text --snapshot-ids $snapshot --query Snapshots[].StartTime | awk -F "T" '{printf "%s\n", $1}')
snapshot_date_in_seconds=$(date "--date=$snapshot_date" +%s)
snapshot_description=$(aws ec2 describe-snapshots --snapshot-id $snapshot --region $region --query Snapshots[].Description)
if (( $snapshot_date_in_seconds <= $retention_date_in_seconds )); then
log "DELETING snapshot $snapshot. Description: $snapshot_description ..."
aws ec2 delete-snapshot --region $region --snapshot-id $snapshot
else
log "Not deleting snapshot $snapshot. Description: $snapshot_description ..."
fi
done
done
}
## SCRIPT COMMANDS ##
log_setup
prerequisite_check
# Grab all volume IDs attached to this instance
volume_list=$(aws ec2 describe-volumes --region $region --filters Name=attachment.instance-id,Values=$instance_id --query Volumes[].VolumeId --output text)
snapshot_volumes
cleanup_snapshots