Merge pull request googleapis#3188 from tseaver/1679-generalize-pubsub-iam-for-storage

Factor common IAM policy bits into 'google.cloud.iam'.

Author: tseaver

core/google/cloud/iam.py

@@ -0,0 +1,242 @@
+# Copyright 2017 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Non-API-specific IAM policy definitions
+
+For allowed roles / permissions, see:
+https://cloud.google.com/iam/docs/understanding-roles
+"""
+
+import collections
+import warnings
+
+# Generic IAM roles
+
+OWNER_ROLE = 'roles/owner'
+"""Generic role implying all rights to an object."""
+
+EDITOR_ROLE = 'roles/editor'
+"""Generic role implying rights to modify an object."""
+
+VIEWER_ROLE = 'roles/viewer'
+"""Generic role implying rights to access an object."""
+
+_ASSIGNMENT_DEPRECATED_MSG = """\
+Assigning to '{}' is deprecated.  Replace with 'policy[{}] = members."""
+
+
+class Policy(collections.MutableMapping):
+    """IAM Policy
+
+    See:
+    https://cloud.google.com/iam/reference/rest/v1/Policy
+
+    :type etag: str
+    :param etag: ETag used to identify a unique of the policy
+
+    :type version: int
+    :param version: unique version of the policy
+    """
+    _OWNER_ROLES = (OWNER_ROLE,)
+    """Roles mapped onto our ``owners`` attribute."""
+
+    _EDITOR_ROLES = (EDITOR_ROLE,)
+    """Roles mapped onto our ``editors`` attribute."""
+
+    _VIEWER_ROLES = (VIEWER_ROLE,)
+    """Roles mapped onto our ``viewers`` attribute."""
+
+    def __init__(self, etag=None, version=None):
+        self.etag = etag
+        self.version = version
+        self._bindings = {}
+
+    def __iter__(self):
+        return iter(self._bindings)
+
+    def __len__(self):
+        return len(self._bindings)
+
+    def __getitem__(self, key):
+        return self._bindings[key]
+
+    def __setitem__(self, key, value):
+        self._bindings[key] = frozenset(value)
+
+    def __delitem__(self, key):
+        del self._bindings[key]
+
+    @property
+    def owners(self):
+        """Legacy access to owner role."""
+        result = set()
+        for role in self._OWNER_ROLES:
+            for member in self._bindings.get(role, ()):
+                result.add(member)
+        return frozenset(result)
+
+    @owners.setter
+    def owners(self, value):
+        """Update owners."""
+        warnings.warn(
+            _ASSIGNMENT_DEPRECATED_MSG.format('owners', OWNER_ROLE),
+            DeprecationWarning)
+        self._bindings[OWNER_ROLE] = list(value)
+
+    @property
+    def editors(self):
+        """Legacy access to editor role."""
+        result = set()
+        for role in self._EDITOR_ROLES:
+            for member in self._bindings.get(role, ()):
+                result.add(member)
+        return frozenset(result)
+
+    @editors.setter
+    def editors(self, value):
+        """Update editors."""
+        warnings.warn(
+            _ASSIGNMENT_DEPRECATED_MSG.format('editors', EDITOR_ROLE),
+            DeprecationWarning)
+        self._bindings[EDITOR_ROLE] = list(value)
+
+    @property
+    def viewers(self):
+        """Legacy access to viewer role."""
+        result = set()
+        for role in self._VIEWER_ROLES:
+            for member in self._bindings.get(role, ()):
+                result.add(member)
+        return frozenset(result)
+
+    @viewers.setter
+    def viewers(self, value):
+        """Update viewers."""
+        warnings.warn(
+            _ASSIGNMENT_DEPRECATED_MSG.format('viewers', VIEWER_ROLE),
+            DeprecationWarning)
+        self._bindings[VIEWER_ROLE] = list(value)
+
+    @staticmethod
+    def user(email):
+        """Factory method for a user member.
+
+        :type email: str
+        :param email: E-mail for this particular user.
+
+        :rtype: str
+        :returns: A member string corresponding to the given user.
+        """
+        return 'user:%s' % (email,)
+
+    @staticmethod
+    def service_account(email):
+        """Factory method for a service account member.
+
+        :type email: str
+        :param email: E-mail for this particular service account.
+
+        :rtype: str
+        :returns: A member string corresponding to the given service account.
+        """
+        return 'serviceAccount:%s' % (email,)
+
+    @staticmethod
+    def group(email):
+        """Factory method for a group member.
+
+        :type email: str
+        :param email: An id or e-mail for this particular group.
+
+        :rtype: str
+        :returns: A member string corresponding to the given group.
+        """
+        return 'group:%s' % (email,)
+
+    @staticmethod
+    def domain(domain):
+        """Factory method for a domain member.
+
+        :type domain: str
+        :param domain: The domain for this member.
+
+        :rtype: str
+        :returns: A member string corresponding to the given domain.
+        """
+        return 'domain:%s' % (domain,)
+
+    @staticmethod
+    def all_users():
+        """Factory method for a member representing all users.
+
+        :rtype: str
+        :returns: A member string representing all users.
+        """
+        return 'allUsers'
+
+    @staticmethod
+    def authenticated_users():
+        """Factory method for a member representing all authenticated users.
+
+        :rtype: str
+        :returns: A member string representing all authenticated users.
+        """
+        return 'allAuthenticatedUsers'
+
+    @classmethod
+    def from_api_repr(cls, resource):
+        """Create a policy from the resource returned from the API.
+
+        :type resource: dict
+        :param resource: resource returned from the ``getIamPolicy`` API.
+
+        :rtype: :class:`Policy`
+        :returns: the parsed policy
+        """
+        version = resource.get('version')
+        etag = resource.get('etag')
+        policy = cls(etag, version)
+        for binding in resource.get('bindings', ()):
+            role = binding['role']
+            members = sorted(binding['members'])
+            policy._bindings[role] = members
+        return policy
+
+    def to_api_repr(self):
+        """Construct a Policy resource.
+
+        :rtype: dict
+        :returns: a resource to be passed to the ``setIamPolicy`` API.
+        """
+        resource = {}
+
+        if self.etag is not None:
+            resource['etag'] = self.etag
+
+        if self.version is not None:
+            resource['version'] = self.version
+
+        if len(self._bindings) > 0:
+            bindings = resource['bindings'] = []
+            for role, members in sorted(self._bindings.items()):
+                if len(members) > 0:
+                    bindings.append(
+                        {'role': role, 'members': sorted(set(members))})
+
+            if len(bindings) == 0:
+                del resource['bindings']
+
+        return resource
+
+
+collections.MutableMapping.register(Policy)