Support parameters in the format supported by "awscli".

e.g.

    [
      {
        "ParameterKey": "string",
        "ParameterValue": "string",
        "UsePreviousValue": true|false
      }
    ]

It's irksome that aws-sdk doesn't support this out-of-the-box.

bin/stackup

@@ -162,7 +162,9 @@ Clamp do
       return parameters unless parameters.is_a?(Array)
       {}.tap do |result|
         parameters.each do |p|
-          result[p["parameter_key"]] = p["parameter_value"]
+          key = p.fetch("ParameterKey") { p.fetch("parameter_key") }
+          value = p.fetch("ParameterValue") { p.fetch("parameter_value") }
+          result[key] = value
         end
       end
     end

examples/parameters.json

@@ -1,6 +1,6 @@
 [
   {
-    "parameter_key": "IndexDoc",
-    "parameter_value": "default.htm"
+    "ParameterKey": "IndexDoc",
+    "ParameterValue": "default.htm"
   }
 ]

lib/stackup/stack.rb

@@ -303,15 +303,32 @@ def modify_stack
     end
 
     def normalise_parameters(arg)
-      return arg unless arg.is_a?(Hash)
-      arg.map do |key, value|
-        {
-          :parameter_key => key,
-          :parameter_value => value
-        }
+      if arg.is_a?(Hash)
+        return arg.map do |key, value|
+          {
+            :parameter_key => key,
+            :parameter_value => value
+          }
+        end
+      end
+      arg.map do |parameter|
+        normalise_parameter_keys(parameter)
+      end
+    end
+
+    def normalise_parameter_keys(input)
+      {}.tap do |output|
+        input.each do |key, value|
+          output[normalise_parameter_key(key)] = value
+        end
       end
     end
 
+    def normalise_parameter_key(s)
+      return s if s.is_a?(Symbol)
+      s.gsub(/([a-z])([A-Z])/, '\1_\2').downcase
+    end
+
   end
 
 end

spec/stackup/stack_spec.rb

@@ -157,6 +157,30 @@ def create_or_update
 
       end
 
+      context "with :parameters in awscli form" do
+
+        before do
+          options[:parameters] = [{
+            "ParameterKey" => "foo",
+            "ParameterValue" => "bar"
+          }]
+        end
+
+        it "converts them to an Array" do
+          expected_parameters = [
+            {
+              "parameter_key" => "foo",
+              "parameter_value" => "bar"
+            }
+          ]
+          create_or_update
+          expect(cf_client).to have_received(:create_stack) do |options|
+            expect(options[:parameters]).to eq(expected_parameters)
+          end
+        end
+
+      end
+
     end
 
   end