added simple yaml template file processor

template.sh

@@ -0,0 +1,112 @@
+#!/bin/bash -e
+
+while test $# -gt 0; do
+    case "$1" in
+        (-h|--help) cat <<EOF
+$0 [OPTIONS] FILE
+
+OPTIONS
+
+  -v, --var  name=value  Set environment variable to be used in the template.
+
+  -p, --pwd  name        Generate a random password with the given name.
+
+FILE
+
+  A template file. In the template file, you may use bash variables
+  and execute bash commands, e.g. you are allowed wo use the \$()
+  expression.
+
+DESCRIPTION
+
+  Parse a template file and generate an instance for it, using the
+  environment variables nd the given parameters. The use of
+  environment variables and command line option --var is equivalent.
+
+EXAMPLE
+
+  file wordpress.tpl
+-----------------------------------------------------------------------------
+version: '3.3'
+services:
+  mysql:
+    image: mysql
+    volumes:
+      - type: bind
+        source: /var/volumes/\${NAME}/mysql
+        target: /var/lib/mysql
+    environment:
+      - 'MYSQL_DATABASE=wordpress'
+      - 'MYSQL_USER=wordpress'
+      - 'MYSQL_PASSWORD=\${PASSWORD}'
+      - 'MYSQL_ROOT_PASSWORD=\$(pwgen 40 1)'
+    deploy:
+      placement:
+        constraints:
+          - node.labels.location == ug
+  wordpress:
+    image: wordpress
+    ports:
+      - \${PORT}:80
+    volumes:
+      - type: bind
+        source: /var/volumes/\${NAME}/wordpress
+        target: /var/www/html
+    environment:
+      - 'WORDPRESS_DB_HOST=mysql'
+      - 'WORDPRESS_DB_NAME=wordpress'
+      - 'WORDPRESS_DB_USER=wordpress'
+      - 'WORDPRESS_DB_PASSWORD=\${PASSWORD}'
+    deploy:
+      placement:
+        constraints:
+          - node.labels.location == ug
+-----------------------------------------------------------------------------
+
+  create instance from template:
+
+  $0 -v NAME=my-site -v PORT=8006 -p PASSWORD wordpress.tpl > my-site.yaml
+
+EOF
+                    exit;;
+        (-v|--var) shift;
+                   if [[ $1 =~ ^[a-zA-Z][a-zA-Z0-9_]*= ]]; then
+                       export $1
+                   else
+                       echo "ERROR not a variable assignment: $1" 1>&2
+                       echo " see: $0 --help" 1>&2
+                       exit 1
+                   fi;;
+        (-p|--pwd) shift;
+                   if [[ $1 =~ ^[a-zA-Z][a-zA-Z0-9_]*$ ]]; then
+                       export $1=$(pwgen 40 1)
+                   else
+                       echo "ERROR not a variable name: $1" 1>&2
+                       echo " see: $0 --help" 1>&2
+                       exit 1
+                   fi;;
+        (*) if test $# -ne 1 -o ! -e "$1"; then
+                echo "ERROR please specify exactly one template file $*" 1>&2
+                echo " this not a template file: $*" 1>&2
+                echo " see: $0 --help" 1>&2
+                exite
+            fi
+            file="$1";
+    esac
+    if test $# -lt 1; then
+        echo "ERROR too few arguments" 1>&2
+        echo " see: $0 --help" 1>&2
+        exit 1
+    fi
+    shift
+done
+
+if ! test -e "$file"; then
+    echo "ERROR please specify a template file" 1>&2
+    echo " see: $0 --help" 1>&2
+    exit 1
+fi
+
+eval "cat <<EOFXXXX
+$(<$file)
+EOFXXXX"