list-task-defs-in-use.sh

#!/bin/bash

state_machine_arns=$(aws stepfunctions list-state-machines | jq -r .stateMachines[].stateMachineArn)

for state_machine_arn in ${state_machine_arns}; do
  echo "{ $(aws stepfunctions describe-state-machine --state-machine-arn ${state_machine_arn} \
    | jq -r .definition \
    | jq . \
    | grep TaskDefinition) }" \
    | jq -r .TaskDefinition
done

clusters=$(aws ecs list-clusters | jq -r .clusterArns[])

for cluster in ${clusters}; do
  task_arns=$(aws ecs list-tasks --cluster ${cluster} | jq -r .taskArns[])
  if [ -n "${task_arns}" ]; then
    aws ecs describe-tasks --tasks ${task_arns} --cluster ${cluster} | jq -r .tasks[].taskDefinitionArn
  fi
done