Delete unused Launch Configuration. Based on http://www.markomedia.com.au/delete-launch-config-programatically-aws/

delete_unused_launch_configurations.sh

#!/bin/bash


# Check if a value exists in an array
# @param $1 mixed  Needle
# @param $2 array  Haystack
# @return  Success (0) if value exists, Failure (1) otherwise
# Usage: in_array "$needle" "${haystack[@]}"
# See: http://fvue.nl/wiki/Bash:_Check_if_array_element_exists
in_array() {
    local hay needle=$1
    shift
    for hay; do
        [[ $hay == "$needle" ]] && return 0
    done
    return 1
}

# Get all launch configuration names that have been created for this AWS account
allconfigs="$(aws autoscaling describe-launch-configurations --query 'LaunchConfigurations[].LaunchConfigurationName' --output text )"
IFS=$'\t' read -r -a configs <<< "$allconfigs"

# Get all active launch configurations names that are currently associated with running instances
allinstances="$(aws autoscaling describe-auto-scaling-instances --query 'AutoScalingInstances[].LaunchConfigurationName' --output text )"
IFS=$'\t' read -r -a instances <<< "$allinstances"

# Get all active launch configuration names that are currently associated with launch configuration groups
allgroups="$(aws autoscaling describe-auto-scaling-groups --query 'AutoScalingGroups[].LaunchConfigurationName' --output text )"
IFS=$'\t' read -r -a groups <<< "$allgroups"

# merge group configs and active instances configs into one array.  We need to keep them, and remove the rest
IFS=$'\t' read -r -a groupsandinstances <<< "$(for R in "${instances[@]}" "${groups[@]}" ; do echo "$R" ; done | sort -du | tr '\n' '\t')"

#Loop through all configs and check against active ones to determine whether they need to be deleted
for i in "${configs[@]}"
do
    if in_array $i "${groupsandinstances[@]}" ; then
        echo active "${i}"
    else
        echo deleting "${i}"
        aws autoscaling delete-launch-configuration --launch-configuration-name "${i}"
    fi
done