snapshot.sh

#!/bin/sh
# see also: http://d.hatena.ne.jp/rx7/20100606/p1

source /etc/profile.d/aws-apitools-common.sh

if [ -r $HOME/.snapshotrc ]
then
    source $HOME/.snapshotrc
fi

if [ -z "$PK" ]
then
    echo "PK is not defined" >&2;
    exit 1;
fi
if [ -z "$CERT" ]
then
    echo "CERT is not defined" >&2;
    exit 1;
fi
if [ -z "$GENERATIONS" ]
then
    echo "GENERATIONS is not defined" >&2;
    exit 1;
fi

region=`ec2-metadata|grep placement|cut -d' ' -f2|sed 's/[a-z]$//'`
instance=`ec2-metadata|grep instance-id|cut -d' ' -f2`
vol=`ec2-describe-instances -K $PK -C $CERT --region $region $instance|grep 'vol-'|awk '{print $3}'`

snapshot=`ec2-create-snapshot -K $PK -C $CERT --region $region -d 'backup by snapshot.sh' $vol|awk '{print $2}'`
echo '[took snapshot]' $snapshot

count=1
existings=`ec2-describe-snapshots -K $PK -C $CERT --region $region |grep $vol|grep 'backup by snapshot.sh'|sort -k5 -r|awk '{print $2}' | grep -v $snapshot`
for target in $existings;
do
    if [ $count -lt $GENERATIONS ]
    then
        echo '[keeping]      ' $target
    else
        echo '[deleting]     ' $target
        ec2-delete-snapshot -K $PK -C $CERT --region $region $target > /dev/null 2>&1
    fi
    count=`expr ${count} + 1`
done