Allow retrying some failed requests

Connection Errors can be transient and there are many clients (including
auth_token middleware) that allow retrying requests that fail.

We should support this in the session, disabled by default, rather than
have multiple implementations for it.

For the moment I have purposefully not added it as an option to
Session.__init__ though I can see arguments for it. This can be added
later if there becomes a particular need.

I have also purposefully distinguished between Connection Errors (and
connect_retries) and HTTP errors. I don't know a good way to generalize
retrying on HTTP errors and they can be added later if required.

Blueprint: session-retries
Change-Id: Ia219636663980433ddb9c00c6df7c8477df4ef99

1 files changed, 9 insertions, 1 deletions

diff --git a/keystoneclient/adapter.py b/keystoneclient/adapter.py
index 24403f9..3d65d78 100644
--- a/keystoneclient/adapter.py
+++ b/keystoneclient/adapter.py
@@ -27,7 +27,8 @@ class Adapter(object):
     @utils.positional()
     def __init__(self, session, service_type=None, service_name=None,
                  interface=None, region_name=None, endpoint_override=None,
-                 version=None, auth=None, user_agent=None):
+                 version=None, auth=None, user_agent=None,
+                 connect_retries=None):
         """Create a new adapter.
 
         :param Session session: The session object to wrap.
@@ -41,6 +42,10 @@ class Adapter(object):
         :param auth.BaseAuthPlugin auth: An auth plugin to use instead of the
                                          session one.
         :param str user_agent: The User-Agent string to set.
+        :param int connect_retries: the maximum number of retries that should
+                                    be attempted for connection errors.
+                                    Default None - use session default which
+                                    is don't retry.
         """
         self.session = session
         self.service_type = service_type
@@ -51,6 +56,7 @@ class Adapter(object):
         self.version = version
         self.user_agent = user_agent
         self.auth = auth
+        self.connect_retries = connect_retries
 
     def _set_endpoint_filter_kwargs(self, kwargs):
         if self.service_type:
@@ -75,6 +81,8 @@ class Adapter(object):
             kwargs.setdefault('auth', self.auth)
         if self.user_agent:
             kwargs.setdefault('user_agent', self.user_agent)
+        if self.connect_retries is not None:
+            kwargs.setdefault('connect_retries', self.connect_retries)
 
         return self.session.request(url, method, **kwargs)