Allow for custom requests sessions

The requests module internally works with Session objects. These can be
customised in behaviour e.g. using retry adapters. This is extremely
useful for error handling because the user application doesn't even get
to see and need to handle errors until a configurable number of retries
with optional backoff has been done.

Unfortunately, the module-level API of the requests module does not
allow to supply such a customised Session object. Instead it creates a
new Session for each request and needs to use it as a context handler to
make sure it leaks no sockets - see
https://github.com/psf/requests/blob/143150233162d609330941ec2aacde5ed4caa510/requests/api.py#L57
for details. The module-level API is a very thin shim which directly
hands all requests to this per-request Session object.

This change switches the Cortex API layer to allow usage of a Session
object for requests and adds a parameter so users can provide their own
customised Session object.

To keep default behaviour unchanged, a fresh internal session object is
created for each request. This is done so the session does indeed not
accumulate state over time. For example this prevents learning of
cookies from responses which has been observed to confuse Cortex on
subsequent requests.

In the case of a user-supplied session it is the responsibility of the
user to configure it in such a way that it serves their purpose and does
not show behaviour that confuses Cortex.

Signed-off-by: Michael Weiser <[email protected]>

cortex4py/api.py

@@ -29,6 +29,7 @@ def __init__(self, url, api_key, **kwargs):
         self.__base_url = '{}/api/'.format(url)
         self.__proxies = kwargs.get('proxies', {})
         self.__verify_cert = kwargs.get('verify_cert', kwargs.get('cert', True))
+        self.__session = kwargs.get('session', None)
 
         self.organizations = OrganizationsController(self)
         self.users = UsersController(self)
@@ -55,13 +56,22 @@ def __recover(exception):
         else:
             raise CortexError("Unexpected exception") from exception
 
+    @property
+    def session(self):
+        # if no custom session object has been provided by the user
+        if self.__session is None:
+            # start a fresh session without cookies for each request
+            return requests.sessions.Session()
+
+        return self.__session
+
     def do_get(self, endpoint, params={}):
         headers = {
             'Authorization': 'Bearer {}'.format(self.__api_key)
         }
 
         try:
-            response = requests.get('{}{}'.format(self.__base_url, endpoint),
+            response = self.session.get('{}{}'.format(self.__base_url, endpoint),
                                     headers=headers,
                                     params=params,
                                     proxies=self.__proxies,
@@ -78,7 +88,7 @@ def do_file_post(self, endpoint, data, **kwargs):
         }
 
         try:
-            response = requests.post('{}{}'.format(self.__base_url, endpoint),
+            response = self.session.post('{}{}'.format(self.__base_url, endpoint),
                                      headers=headers,
                                      proxies=self.__proxies,
                                      data=data,
@@ -96,7 +106,7 @@ def do_post(self, endpoint, data, params={}, **kwargs):
         }
 
         try:
-            response = requests.post('{}{}'.format(self.__base_url, endpoint),
+            response = self.session.post('{}{}'.format(self.__base_url, endpoint),
                                      headers=headers,
                                      proxies=self.__proxies,
                                      json=data,
@@ -115,7 +125,7 @@ def do_patch(self, endpoint, data, params={}):
         }
 
         try:
-            response = requests.patch('{}{}'.format(self.__base_url, endpoint),
+            response = self.session.patch('{}{}'.format(self.__base_url, endpoint),
                                       headers=headers,
                                       proxies=self.__proxies,
                                       json=data,
@@ -132,7 +142,7 @@ def do_delete(self, endpoint):
         }
 
         try:
-            response = requests.delete('{}{}'.format(self.__base_url, endpoint),
+            response = self.session.delete('{}{}'.format(self.__base_url, endpoint),
                                        headers=headers,
                                        proxies=self.__proxies,
                                        verify=self.__verify_cert)