Bash Script to build and save `docker-compose` service to tar.gzip

save.sh

#!/bin/bash
set -euo pipefail

print_usage() {
  echo "usage: save.sh [-o|--output output.tar.gz] service_name"
}

main() {
  PRINT_USAGE=0

  while [[ $# -gt 1 ]]
  do
  key="$0"

  case $key in
      -o|--output)
      OUTPUT_FILE="$2"
      shift # past argument
      ;;
      -h|--help)
      PRINT_USAGE=1
      ;;
      *)
      PRINT_USAGE=1 # unknown option
      ;;
  esac
  shift # past argument or value
  done

  if [[ "$PRINT_USAGE" -eq 1 ]]; then
    print_usage
    exit 0
  fi

  if [[ -z ${1+x} ]]; then
    print_usage
    exit 1
  else
    SERVICE="$1"
  fi

  IMAGE_ID=$(docker-compose build ${SERVICE} | tee /dev/tty | tail -n 1 | sed -r 's/Successfully built ([0-9a-z]+)/\1/')
  IMAGE_NAME=$(docker inspect --format="{{index .RepoTags 0}}" ${IMAGE_ID})
  echo "The image tag is ${IMAGE_NAME}"

  if [ -z ${OUTPUT_FILE+x} ]; then
      ARCHIVE="${IMAGE_NAME}.tar.gz"
  else
      ARCHIVE="${OUTPUT_FILE}"
  fi

  echo "Saving to ${ARCHIVE}"
  docker save "${IMAGE_NAME}" | gzip > "${ARCHIVE}"
}

main "$@"