Bash script to get the Datomic Cloud system name

datomic-system-name.sh

#!/usr/bin/env bash
set -eo pipefail

if [[ "$#" -eq 0 ]]; then
  cat <<EOF
usage: $(basename $0) <REGION> [OPTIONS]

  REGION  - a valid AWS region e.g. us-east-1
  OPTIONS - any valid AWS CLI options e.g. --profile home
EOF
else
  region="${1}"
  shift

  aws ec2 describe-instances --region ${region} \
    --filters "Name=tag-key,Values=datomic:tx-group" "Name=instance-state-name,Values=running" \
    --query 'Reservations[*].Instances[*].[Tags[?Key==`datomic:system`].Value]' \
    --output text \
    $*
fi