Add the ability to customize lambda function upload name

docs/lambdas.rst

@@ -87,6 +87,7 @@ The following is the anatomy of a lambda in gordon.
       timeout: { NUMBER }
       runtime: { RUNTIME_NAME }
       description: { STRING }
+      function-name: { STRING }
       build: { STRING }
       role: { MAP }
       vpc: { STRING }
@@ -307,6 +308,25 @@ Description                  Human-readable description for your lambda.
       description: This is a really simple function which says hello
 
 
+function-name
+^^^^^^^^^^^^^^^^^^^^^^
+
+===========================  ============================================================================================================
+Name                         ``function-name``
+Required                     No
+Default                      *Empty*
+Valid types                  ``string``, ``reference``
+Description                  Base function name to upload to AWS
+===========================  ============================================================================================================
+
+.. code-block:: yaml
+
+  lambdas:
+    hello_world:
+      code: functions.py
+      function-name: goodbye_world
+
+
 .. _lambda-build:
 
 build

gordon/exceptions.py

@@ -174,3 +174,7 @@ class LambdaNotFound(BaseGordonException):
 class ValidationError(BaseGordonException):
     hint = u"  Validation Error: {}"
     code = 24
+
+class InvalidLambdaFunctionName(BaseGordonException):
+    hint = u"Lambda {} cannot have name {}"
+    code = 25

gordon/resources/lambdas.py

@@ -185,6 +185,48 @@ def get_role(self):
             Policies=self._get_policies()
         )
 
+    def get_function_name(self):
+        """Returns the optional FunctionName this lambda should use for
+        deployment. If the ``function-name` field is provided in the lambda's
+        settings, the name uploaded will be in the format of:
+            "Fn::Join": [
+              "-",
+              [
+                  ``function-name``,
+                  {
+                    "Ref":"Stage"
+                  },
+                  {
+                    "Ref":"AWS::Region"
+                  }
+              ]
+            ]
+        ``function-name`` can be a ref or string"""
+
+        function_name = self.settings.get('function-name')
+
+        def _join_env_refs(*values):
+            values = list(values)
+            values.append(troposphere.Ref("Stage"))
+            values.append(troposphere.Ref(troposphere.AWS_REGION))
+            return troposphere.Join("-", values)
+
+        if isinstance(function_name, six.string_types):
+            return _join_env_refs(
+                    utils.valid_cloudformation_name(self.app.name),
+                    utils.valid_cloudformation_name(function_name))
+        elif isinstance(function_name, troposphere.Ref):
+            return _join_env_refs(
+                    utils.valid_cloudformation_name(self.app.name),
+                    function_name)
+        elif function_name is None:
+            pass
+        else:
+            raise exceptions.InvalidLambdaFunctionName(self.name, function_name)
+
+
+
+
     def get_bucket_key(self):
         """Return the S3 bucket key for this lambda."""
         filename = '_'.join(self.in_project_name.split(':')[1:])
@@ -258,6 +300,9 @@ def register_resources_template(self, template):
                 SecurityGroupIds=vpc.settings['security-groups'],
                 SubnetIds=vpc.settings['subnet-ids']
             )
+        function_name = self.get_function_name()
+        if function_name is not None:
+            extra["FunctionName"] = function_name
 
         function = template.add_resource(
             awslambda.Function(