Add convenience method to simply add statements to a Policy

cumulus/util/policy_mutator.py

@@ -0,0 +1,31 @@
+import awacs
+import troposphere
+from awacs.aws import PolicyDocument  # noqa
+from troposphere.iam import Policy  # noqa
+
+
+class PolicyMutator:
+    def __init__(self):
+        pass
+
+    @staticmethod
+    def add_statement_to_policy(policy, statement):
+        """
+
+        :type policy: troposphere.iam.Policy
+        :type statement: awacs.aws.Statement
+        """
+        if type(policy) is not troposphere.iam.Policy:
+            raise AssertionError("Expected to find troposphere.iam.Policy but found: %s" % type(policy))
+
+        if not isinstance(policy.PolicyDocument, awacs.aws.PolicyDocument):
+            msg = "Expected policy.PolicyDocument to be awacs.aws.PolicyDocument but found: %s" \
+                  % type(policy.PolicyDocument)
+            raise AssertionError(msg)
+
+        if not isinstance(statement, awacs.aws.Statement):
+            msg = "Expected statement to be awacs.aws.Statement but found: %s " % type(statement)
+            raise AssertionError(msg)
+
+        policy.PolicyDocument.Statement.append(statement)
+        return policy

tests/unit/util/test_policy_mutator.py

@@ -0,0 +1,97 @@
+# try:
+#     #python 3
+#     from unittest.mock import patch
+# except:
+#     #python 2
+#     from mock import patch
+
+import unittest
+
+import awacs
+from awacs import aws  # noqa
+import troposphere
+from troposphere import iam
+
+from cumulus.util.policy_mutator import PolicyMutator
+
+DEFAULT_STATEMENT_NAME = "DefaultStatement"
+
+
+class TestPolicyMutator(unittest.TestCase):
+
+    def setUp(self):
+        pass
+        self.simple_policy = iam.Policy(
+            PolicyName="TestPolicy",
+            PolicyDocument=awacs.aws.PolicyDocument(
+                Version="2012-10-17",
+                Id="PipelinePolicy",
+                Statement=[
+                    awacs.aws.Statement(
+                        Sid=("%s" % DEFAULT_STATEMENT_NAME),
+                        Effect=awacs.aws.Allow,
+                        Action=[awacs.aws.Action("s3", "*")],
+                        Resource=['*'],
+                    ),
+                ],
+            )
+        )
+
+        self.dummy_statement = awacs.aws.Statement()
+
+    def tearDown(self):
+        pass
+        del self.simple_policy
+
+    def test_should_raise_assertion_error_on_wrong_policy_type(self):
+        policy = "not what you want"
+        self.assertRaises(
+            AssertionError,
+            PolicyMutator.add_statement_to_policy,
+            policy,
+            self.dummy_statement,
+        )
+
+    def test_should_raise_assertion_error_if_policydocument_is_not_awacs(self):
+        policy = troposphere.iam.Policy(
+            PolicyDocument={}
+        )
+        self.assertRaises(
+            AssertionError,
+            PolicyMutator.add_statement_to_policy,
+            policy,
+            self.dummy_statement,
+        )
+
+    def test_should_raise_assertion_error_on_wrong_statement_type(self):
+        policy = self.simple_policy
+        self.assertRaises(
+            AssertionError,
+            PolicyMutator.add_statement_to_policy,
+            policy,
+            {"statment": "is wrong"},
+        )
+
+    def test_should_add_statement_to_existing_policy(self):
+        pass
+        policy = self.simple_policy
+        lambda_policy_name = 'LambdaPolicy'
+        statement = awacs.aws.Statement(
+                        Sid=('%s' % lambda_policy_name),
+                        Effect=awacs.aws.Allow,
+                        Action=[
+                            awacs.aws.Action("lambda", "*")
+                        ],
+                        Resource=["*"]
+                    )
+
+        found_default = filter(lambda x: x.Sid == DEFAULT_STATEMENT_NAME, policy.PolicyDocument.Statement)
+        self.assertTrue(found_default, "Did not find the statement I was looking for")
+        self.assertIsInstance(found_default[0], awacs.aws.Statement)
+
+        policy = PolicyMutator.add_statement_to_policy(policy, statement)
+
+        # self.assertFalse(policy.PolicyDocument.Statement)
+        found_sut = filter(lambda x: x.Sid == lambda_policy_name, policy.PolicyDocument.Statement)
+        self.assertTrue(found_sut, "Did not find the statement I was looking for")
+        self.assertIsInstance(found_default[0], awacs.aws.Statement)