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Last active March 7, 2023 12:19
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Deregister an Amazon Machine Image (AMI) and delete its corresponding root device snapshot
#!/usr/bin/env bash
#
# delete-ami
#
# A script to deregister an Amazon Machine Image (AMI) and
# delete its corresponding root device snapshot.
#
##### Functions
# print a message to stderr
warn() {
local fmt="$1"
shift
printf "delete-ami: $fmt\n" "$@" >&2
}
# print a message to stderr and exit with either
# the given status or that of the most recent command
die() {
local st="$?"
if [[ "$1" != *[^0-9]* ]]; then
st="$1"
shift
fi
warn "$@"
exit "$st"
}
# print this script's usage message to stderr
usage() {
cat <<-EOF >&2
Usage: delete-ami -r REGION -a AMI-ID [-h]
Deregister the given AMI and delete its root device snapshot
EOF
}
##### Main
# reset all variables that might be set
region=''
ami_id=''
# parse command line options
while [[ "$1" != '' ]]
do
case $1 in
-r | --region)
region=$2
shift
;;
--region=*)
region=${1#*=}
;;
-a | --ami-id)
ami_id=$2
shift
;;
--ami-id=*)
ami_id=${1#*=}
;;
-h | --help | -\?)
usage
exit 0
;;
--*)
warn "unknown option -- ${1#--}"
usage
exit 1
;;
*)
warn "unknown option -- ${1#-}"
usage
exit 1
;;
esac
shift
done
# check for required command line options
if [[ ! $region ]]; then
die 1 "option '--region=REGION' not given; see --help"
elif [[ ! $ami_id ]]; then
die 1 "option '--ami-id=AMI_ID' not given; see --help"
fi
# check for dependencies
for cmd in {aws,jq}; do
if ! command -v $cmd > /dev/null; then
die 1 'required command "%s" was not found' "$cmd"
fi
done
AMI_DESCRIPTION=$(aws --region "$region" ec2 describe-images --image-ids "$ami_id" 2> /dev/null)
if [[ -z $AMI_DESCRIPTION ]]; then
warn 'unable to find an AMI with the ID "%s"' "$ami_id"
die 1 'run the following command to debug:\n aws --region %s ec2 describe-images --image-ids "%s"' "$region" "$ami_id"
fi
ROOT_DEVICE_NAME=$(printf "$AMI_DESCRIPTION" | jq --raw-output '.[][].RootDeviceName')
SNAPSHOT_ID=$(printf "$AMI_DESCRIPTION" | jq --raw-output ".[][].BlockDeviceMappings[] | select(.DeviceName == \"$ROOT_DEVICE_NAME\") | .Ebs.SnapshotId")
if [[ -z $SNAPSHOT_ID ]]; then
warn 'unable to find a Snapshot ID for the "%s" root device on %s' "$ROOT_DEVICE_NAME" "$ami_id"
die 1 'run the following command to debug:\n aws --region %s ec2 describe-images --image-ids "%s"' "$region" "$ami_id"
else
if ! aws --region "$region" ec2 deregister-image --image-id "$ami_id" > /dev/null; then
die 'image deregistration failed; run the following command to debug:\n aws --region %s ec2 deregister-image --image-id "%s"' "$region" "$ami_id"
fi
if ! aws --region "$region" ec2 delete-snapshot --snapshot-id "$SNAPSHOT_ID" > /dev/null; then
die 'snapshot deletion failed; run the following command to debug:\n aws --region %s ec2 delete-snapshot --snapshot-id "%s"' "$region" "$SNAPSHOT_ID"
fi
fi
exit 0
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