Find the Amazon IAM user associated with a given API Access Key

whohaskey.sh

function whohaskey {
  APIKEY="$1"
  CACHE_DIR=~/.aws/keycache
  mkdir -p $CACHE_DIR
  if [ -f $CACHE_DIR/$APIKEY ]; then
    cat $CACHE_DIR/$APIKEY
    return
  fi
  for USER in $(aws iam list-users | jq -r .Users[].UserName); do
    JSON=$(aws iam list-access-keys --user-name "$USER")
    KEYS=$(echo "$JSON" | jq -r .AccessKeyMetadata[].AccessKeyId)
    for KEY in $KEYS; do
      echo -n '.'
      echo "$USER" > $CACHE_DIR/$KEY
      if [ "$KEY" == "$APIKEY" ]; then
        echo $USER
      fi
    done
  done
}