Add support for specifying variable types using named parameter types

stacker/blueprints/base.py

@@ -40,6 +40,20 @@
 }
 
 
+def normalize_defined_variables(variables):
+    """Looks for any variable definitions that are a "str", and assumes that
+    they're the name of a CloudFormation parameter type, in which case the type
+    is converted to a CFNType.
+
+    Returns:
+        dict: normalized variable definitions
+    """
+    for k, v in variables.iteritems():
+        if isinstance(v["type"], str):
+            v["type"] = CFNType.from_name(v["type"])
+    return variables
+
+
 class CFNParameter(object):
 
     def __init__(self, name, value):
@@ -339,7 +353,8 @@ def get_parameter_definitions(self):
 
         """
         output = {}
-        for var_name, attrs in self.defined_variables().iteritems():
+        defined_variables = self._normalized_defined_variables()
+        for var_name, attrs in defined_variables.iteritems():
             var_type = attrs.get("type")
             if isinstance(var_type, CFNType):
                 cfn_attrs = copy.deepcopy(attrs)
@@ -391,6 +406,9 @@ def defined_variables(self):
         """
         return copy.deepcopy(getattr(self, "VARIABLES", {}))
 
+    def _normalized_defined_variables(self):
+        return normalize_defined_variables(self.defined_variables())
+
     def get_variables(self):
         """Return a dictionary of variables available to the template.
 
@@ -435,7 +453,7 @@ def resolve_variables(self, provided_variables):
 
         """
         self.resolved_variables = {}
-        defined_variables = self.defined_variables()
+        defined_variables = self._normalized_defined_variables()
         variable_dict = dict((var.name, var) for var in provided_variables)
         for var_name, var_def in defined_variables.iteritems():
             value = resolve_variable(

stacker/blueprints/variables/types.py

@@ -120,6 +120,10 @@ def __init__(self, parameter_type):
         """
         self.parameter_type = parameter_type
 
+    @staticmethod
+    def from_name(name):
+        return CFNType(name)
+
 
 CFNString = CFNType("String")
 CFNNumber = CFNType("Number")

stacker/tests/blueprints/test_base.py

@@ -66,7 +66,8 @@ class TestBlueprint(Blueprint):
                 "Param2": {"type": CFNNumber},
                 "Param3": {"type": CFNCommaDelimitedList},
                 "Param4": {"default": "foo", "type": str},
-                "Param5": {"default": 5, "type": int}
+                "Param5": {"default": 5, "type": int},
+                "Param6": {"type": "AWS::EC2::Image::Id"}
             }
 
             def create_template(self):
@@ -86,6 +87,9 @@ def create_template(self):
         },
         "Param3": {
             "Type": "CommaDelimitedList"
+        },
+        "Param6": {
+            "Type": "AWS::EC2::Image::Id"
         }
     },
     "Resources": {}

stacker/tests/fixtures/mock_blueprints.py

@@ -28,12 +28,12 @@ class FunctionalTests(Blueprint):
 
     VARIABLES = {
         "StackerNamespace": {
-            "type": CFNString,
+            "type": "String",
             "description": "The stacker namespace that the tests will use. "
                            "Access to cloudformation will be restricted to "
                            "only allow access to stacks with this prefix."},
         "StackerBucket": {
-            "type": CFNString,
+            "type": "String",
             "description": "The name of the bucket that the tests will use "
                            "for uploading templates."}
     }
@@ -172,38 +172,38 @@ class VPC(Blueprint):
             "default": 2,
         },
         "PrivateSubnets": {
-            "type": CFNCommaDelimitedList,
+            "type": "CommaDelimitedList",
             "description": "Comma separated list of subnets to use for "
                            "non-public hosts. NOTE: Must have as many subnets "
                            "as AZCount"},
         "PublicSubnets": {
-            "type": CFNCommaDelimitedList,
+            "type": "CommaDelimitedList",
             "description": "Comma separated list of subnets to use for "
                            "public hosts. NOTE: Must have as many subnets "
                            "as AZCount"},
         "InstanceType": {
-            "type": CFNString,
+            "type": "String",
             "description": "NAT EC2 instance type.",
             "default": "m3.medium"},
         "BaseDomain": {
-            "type": CFNString,
+            "type": "String",
             "default": "",
             "description": "Base domain for the stack."},
         "InternalDomain": {
-            "type": CFNString,
+            "type": "String",
             "default": "",
             "description": "Internal domain name, if you have one."},
         "CidrBlock": {
-            "type": CFNString,
+            "type": "String",
             "description": "Base CIDR block for subnets.",
             "default": "10.128.0.0/16"},
         "ImageName": {
-            "type": CFNString,
+            "type": "String",
             "description": "The image name to use from the AMIMap (usually "
                            "found in the config file.)",
             "default": "NAT"},
         "UseNatGateway": {
-            "type": CFNString,
+            "type": "String",
             "allowed_values": ["true", "false"],
             "description": "If set to true, will configure a NAT Gateway"
                            "instead of NAT instances.",
@@ -217,7 +217,7 @@ def create_template(self):
 class DiffTester(Blueprint):
     VARIABLES = {
         "InstanceType": {
-            "type": CFNString,
+            "type": "String",
             "description": "NAT EC2 instance type.",
             "default": "m3.medium"},
         "WaitConditionCount": {