List all AMIs not in use by EC2 instances or AutoScalingGroups

unused-amis.sh

#!/bin/bash

function our_amis() {
  aws ec2 describe-images --owners self --query 'Images[*].ImageId' | jq -Sr '.[]'
}

function ec2_amis() {
  aws ec2 describe-instances --query 'Reservations[*].Instances[*].ImageId' | jq -Sr '. | flatten | unique | .[]'
}

function asg_amis() {
  for t in $(aws autoscaling describe-auto-scaling-groups --query 'AutoScalingGroups[*].[LaunchTemplate || MixedInstancesPolicy.LaunchTemplate.LaunchTemplateSpecification]' | jq -r '.[][] | (.LaunchTemplateId + ";" + .Version)'); do
    t=(${t//;/ }); aws ec2 describe-launch-template-versions --launch-template-id ${t[0]} --versions ${t[1]//$/\$} --query 'LaunchTemplateVersions[*].LaunchTemplateData.ImageId' | jq -r '.[]'
  done | sort -u
}

function in_use_amis() {
  { ec2_amis & asg_amis; } | sort -u
}

comm -23 <(our_amis) <(in_use_amis)