#!/bin/bash
usage() {                                 # Function: Print a help message.
  echo "Image Build Script: Creates one or more images using a target in the docker-bake.hcl file"
  echo "USAGE: $0 <subcommand> <options> <build_target> <imagename, imageuser>"
  echo "valid build_target: ${targets[*]};  default: dev"
  echo "### subcommands:"
  echo "try (runs try a container script, see try usage)  $0 try -i"
  echo "tag  (runs image_tag script)"
  echo "info get image info,  info <arch, exists, id>  nothing is all info in json"
  echo "--- option switches (no argument):"
  echo "-o do not overwrite an existing image (default), instead move it to a temporary timestamp tag"
  echo "-i rebuild only the initialization RUN by busting the cache at that point"
  echo "-v show verbose information about the build"
  echo "-a (auto) do not prompt to continue build,  by default will not prompt if non-interactive shell"
  echo "-c after build try out the image by starting a container terminal therein, for dev target this is the default;"
  echo "-x exclude distro from image name;"
  echo "-n for --no_cache"
  echo "-k keep the build scripts (see -w) after the build so they are incorporated into the image"
  echo "-p push to repository; after build push to repository default is hub.docker.com (not need for deploy target)"
  echo "--- options with argument <ARGUMENT>:"
  echo "-e <path to environment file> load any or all of options below via a file"
  echo "-d <LINUX_DISTRO> supported: alpine, debian, ubuntu, default: alpine; if base image set distro will be determined"
  echo "-t <TAG> tag following : in output image name (i.e.  REPO/USER/NAME:TAG), default: latest"
  echo "-u <USER>;  repository user prefix in output image name (i.e.  REPO/USER/NAME:TAG)"
  echo "-r <REPO>;  private repo name, do not use for hub.docker.com (docker.io)"
  echo "-b <BASE_IMAGE>;  used in FROM in Dockerfile, default is official distro image (e.g. alpine:latest)"
  echo "-w <BUILD_DIR>;  set a custom WORKDIR in Dockerfile (in image), default is /build, see -k"
  echo "--- options set ONLY by environment variable (see -e as well)"
  echo "<SYSADMIN_PW> set alternate password for container sysadmin account, default is 'sysadmin'"
  echo "NOTE any option with <CAPTIALIZED> above can be set in environment instead"
  echo "#### examples:"
  echo "$0 -a -d ubuntu -u ucommandit"
  echo "build (without prompt) a local ubuntu image from scratch and label it ucommandit/ubuntu:latest"
}