Merge pull request #42 from pas256/add-statements

Adding a way to put in a policy as is into the kappa config file

@@ -70,9 +70,9 @@ simple/
 
 Within the directory we see:
 
-* kappa.yml.sample which is a sample YAML configuration file for the project
-* _src which is a directory containing the source code for the Lambda function
-* _test which is a directory containing some test data
+* `kappa.yml.sample` which is a sample YAML configuration file for the project
+* `_src` which is a directory containing the source code for the Lambda function
+* `_test` which is a directory containing some test data
 
 The first step is to make a copy of the sample configuration file:
 
@@ -204,3 +204,36 @@ Kappa will figure out what has changed and make the necessary updates for you.
 
 That gives you a quick overview of kappa.  To learn more about it, I recommend
 you check out the tutorial.
+
+Policies
+--------
+
+Hands up who loves writing IAM policies. Yeah, that's what I thought. With
+Kappa, there is a simplified way of writing policies and granting your Lambda
+function the permissions it needs.
+
+The simplified version allows you to specify, in your `kappa.yml` file, the
+ARN of the resource you want to access, and then a list of the API methods you
+want to allow. For example:
+
+```
+policy:
+  resources:
+    - arn: arn:aws:logs:*:*:*
+      actions:
+        - "*"
+```
+
+To express this using the official IAM policy format, you can instead use a
+statement:
+
+```
+policy:
+  statements:
+    - Effect: Allow
+      Resource: "*"
+      Action:
+        - "logs:*"
+```
+
+Both of these do the same thing.

@@ -44,7 +44,8 @@ class Policy(object):
             self.environment)
 
     def document(self):
-        if 'resources' not in self._config['policy']:
+        if ('resources' not in self._config['policy'] and
+                'statements' not in self._config['policy']):
             return None
         document = {"Version": "2012-10-17"}
         statements = []
@@ -59,6 +60,8 @@ class Policy(object):
                 actions.append("{}:{}".format(service, action))
             statement['Action'] = actions
             statements.append(statement)
+        for statement in self._config['policy'].get('statements', []):
+            statements.append(statement)
         return json.dumps(document, indent=2, sort_keys=True)
 
     @property