Initial support for parametrization of descriptor files

dogen/cli.py

@@ -56,6 +56,7 @@ def run(self):
         parser.add_argument('--skip-ssl-verification', action='store_true', help='Should we skip SSL verification when retrieving data?')
         parser.add_argument('--scripts-path', help='Location of the scripts directory containing script packages.')
         parser.add_argument('--additional-script', action='append', help='Location of additional script (can be url). Can be specified multiple times.')
+        parser.add_argument('--param', action='append', dest='params', help='List of key and value pairs (format: KEY=value) used for substitution in the image descriptor. Can be specified multiple times.')
         parser.add_argument('--template', help='Path to custom template (can be url)')
 
         parser.add_argument('path', help="Path to yaml descriptor to process")
@@ -69,6 +70,19 @@ def run(self):
         parser.epilog = epilog
         args = parser.parse_args()
 
+        params = {}
+
+        if args.params:
+            for param in args.params:
+                if '=' not in param:
+                    self.log.error("The --param argument with value '%s' could not be parsed. Please make sure you use the 'KEY=value' format" % param)
+                    sys.exit(1)
+
+                k, v = param.split("=", 1)
+                params[k] = v
+
+        args.params = params
+
         if args.verbose:
             self.log.setLevel(logging.DEBUG)
         else:

dogen/generator.py

@@ -1,8 +1,10 @@
 # -*- coding: utf-8 -*-
 
 import hashlib
+import re
 import os
 import shutil
+import six
 import requests
 import yaml
 import tempfile
@@ -29,6 +31,7 @@ def __init__(self, log, args, plugins=[]):
         self.template = args.template
         self.scripts_path = args.scripts_path
         self.additional_scripts = args.additional_script
+        self.params = args.params
 
         ssl_verify = None
         if args.skip_ssl_verification:
@@ -203,7 +206,16 @@ def _validate_cfg(self):
             plugin.extend_schema(schema)
 
         with open(self.descriptor, 'r') as stream:
-            self.cfg = yaml.safe_load(stream)
+            content = stream.read()
+
+            for k, v in six.iteritems(self.params):
+                self.log.debug("Substituting '%s' with '%s' value..." % (k, v))
+                content = re.sub(r"{{%s.*}}" % k, v, content)
+
+            # See if there any params without substitutions. If yes, use specified default values.
+            content = re.sub(r"{{\w+:(.*)}}", '\g<1>', content)
+
+            self.cfg = yaml.safe_load(content)
 
         c = Core(source_data=self.cfg, schema_data=schema)
         try: