add usage (help) to build script

build

@@ -1,56 +1,79 @@
 #!/bin/bash
 declare targets=(dev arm amd deploy private multi)
 declare OPTION; declare OPTARG; declare OPTIND
-  while getopts 'b:d:t:nyr:u:px' OPTION; do
-    # echo processing: option:$OPTION argument:$OPTARG index:$OPTIND remaining:${@:$OPTIND}
-    case "$OPTION" in
-    b)
-    # CUSTOM BASE IMAGE
-      BASE_IMAGE=$OPTARG
-      ;;
-    d)
-    #   LINUX_DISTRO=$OPTARG
-      LINUX_DISTRO=$OPTARG
-      ;;
-    x)
-    #  Exclude distro from image name
-      exclude_distro=true
-      ;;
-    t)
-      TAG=$OPTARG
-      ;;
-    u)
-      RUSER=$OPTARG
-      ;;
-    y)
-      try=true
-       ;;
-    p)
-      push=true
-       ;;
-    n) 
-      NO_CACHE=true
-    ;;
-    r)  
-      REPO=$OPTARG
-    ;;
-       *)  echo unknown run option -$OPTARG
-        echo "USAGE: build <setup options> target(or target)"
-        echo "available options -d <LINUX_DISTRO>; -t <TAG>; -e execute test script after build; -n for --no_cache "
-    ;;
-    esac
-  done
 
-  shift $((OPTIND - 1))
+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 <setup options> buildtarget <imagename, imageuser>"
+  echo "valid targets: ${targets[*]};  default: dev"
+  echo no argument options:
+  echo "-c 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 "-p push to repository; after build push to repository default is hub.docker.common (not need for deploy target)"
+  echo required argument options:
+  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)"
+}
+
+exit_abnormal() {                         # Function: Exit with error.
+  usage
+  exit ${1:-1}
+}
 
 
-[ $NO_CACHE ] &&  nocache="--no-cache" || nocache=""
+while getopts ':b:d:t:ncr:u:pxh' OPTION; do
+  # echo processing: option:$OPTION argument:$OPTARG index:$OPTIND remaining:${@:$OPTIND}
+  case "$OPTION" in
+  b)
+  # CUSTOM BASE IMAGE
+    BASE_IMAGE=$OPTARG
+    ;;
+  d)
+  #   LINUX_DISTRO=$OPTARG
+    LINUX_DISTRO=$OPTARG
+    ;;
+  x)
+  #  Exclude distro from image name
+    exclude_distro=true
+    ;;
+  t)
+    TAG=$OPTARG
+    ;;
+  u)
+    RUSER=$OPTARG
+    ;;
+  c)
+    try=true
+      ;;
+  p)
+    push=true
+      ;;
+  n) 
+    nocache="--no-cache" 
+  ;;
+  r)  
+    REPO=$OPTARG
+  ;;  
+  h)  
+    exit_abnormal 0
+  ;;
+  *)  
+      echo "unknown $0 option -$OPTARG"
+      exit_abnormal 4
+  ;;
+  esac
+done
+
+shift $((OPTIND - 1))
+
 target=${1:-dev} 
 LINUX_DISTRO=${LINUX_DISTRO:-alpine}
 name=$2
 RUSER=${3:-$RUSER}
 
-
 IMAGE_NAME=$([[ $RUSER ]] && echo ${RUSER}/)${name}$([[ (! $exclude_distro) && $name ]] && echo "-")$([[ ! $exclude_distro ]] && echo ${LINUX_DISTRO})
 if [[ $BASE_IMAGE ]]; then
 echo determining DISTRO of base image: $BASE_IMAGE