Add option for retry number of connection attempts

This patch adds a new option (-r | --retries) to specify how many times the
client should attempt to connect to the Neutron server when using idempotent
methods (GET, PUT and DELETE). The patch also provides more user-friendly
message when it's impossible to connect to Neutron server from CLI and
ensures that connection-related exceptions are raised to the caller by
default when neutronclient is used as a library.

DocImpact
Closes-Bug: #1312225

Change-Id: Id74d7cf9a0e8c5d2cd3ee4851c883d5286bea19d

neutronclient/common/clientmanager.py

@@ -64,7 +64,9 @@ class ClientManager(object):
                  ca_cert=None,
                  log_credentials=False,
                  service_type=None,
-                 timeout=None
+                 timeout=None,
+                 retries=0,
+                 raise_errors=True
                  ):
         self._token = token
         self._url = url
@@ -84,7 +86,8 @@ class ClientManager(object):
         self._ca_cert = ca_cert
         self._log_credentials = log_credentials
         self._timeout = timeout
-        return
+        self._retries = retries
+        self._raise_errors = raise_errors
 
     def initialize(self):
         if not self._url:

neutronclient/neutron/client.py

@@ -46,7 +46,9 @@ def make_client(instance):
                                 token=instance._token,
                                 auth_strategy=instance._auth_strategy,
                                 insecure=instance._insecure,
-                                ca_cert=instance._ca_cert)
+                                ca_cert=instance._ca_cert,
+                                retries=instance._retries,
+                                raise_errors=instance._raise_errors)
         return client
     else:
         raise exceptions.UnsupportedVersion(_("API version %s is not "

neutronclient/shell.py

@@ -97,6 +97,17 @@ def env(*_vars, **kwargs):
     return kwargs.get('default', '')
 
 
+def check_non_negative_int(value):
+    try:
+        value = int(value)
+    except ValueError:
+        raise argparse.ArgumentTypeError(_("invalid int value: %r") % value)
+    if value < 0:
+        raise argparse.ArgumentTypeError(_("input value %d is negative") %
+                                         value)
+    return value
+
+
 COMMAND_V2 = {
     'net-list': network.ListNetwork,
     'net-external-list': network.ListExternalNetwork,
@@ -368,6 +379,13 @@ class NeutronShell(app.App):
             nargs=0,
             default=self,  # tricky
             help=_("Show this help message and exit."))
+        parser.add_argument(
+            '-r', '--retries',
+            metavar="NUM",
+            type=check_non_negative_int,
+            default=0,
+            help=_("How many times the request to the Neutron server should "
+                   "be retried if it fails."))
         # Global arguments
         parser.add_argument(
             '--os-auth-strategy', metavar='<auth-strategy>',
@@ -650,6 +668,8 @@ class NeutronShell(app.App):
             insecure=self.options.insecure,
             ca_cert=self.options.os_cacert,
             timeout=self.options.timeout,
+            retries=self.options.retries,
+            raise_errors=False,
             log_credentials=True)
         return
 

neutronclient/tests/unit/test_shell.py

@@ -128,8 +128,8 @@ class ShellTest(testtools.TestCase):
             username='test', user_id='',
             password='test', region_name='', api_version={'network': '2.0'},
             auth_strategy='keystone', service_type='network',
-            endpoint_type='publicURL', insecure=False, ca_cert=None,
+            endpoint_type='publicURL', insecure=False, ca_cert=None, retries=0,
-            log_credentials=True, timeout=None)
+            raise_errors=False, log_credentials=True, timeout=None)
         neutron_shell.run_subcommand(['quota-list'])
         self.mox.ReplayAll()
         cmdline = ('--os-username test '

neutronclient/tests/unit/test_ssl.py

@@ -62,6 +62,8 @@ class TestSSL(testtools.TestCase):
             url=mox.IgnoreArg(),
             username=mox.IgnoreArg(),
             user_id=mox.IgnoreArg(),
+            retries=mox.IgnoreArg(),
+            raise_errors=mox.IgnoreArg(),
             log_credentials=mox.IgnoreArg(),
             timeout=mox.IgnoreArg(),
         )
@@ -94,6 +96,8 @@ class TestSSL(testtools.TestCase):
             url=mox.IgnoreArg(),
             username=mox.IgnoreArg(),
             user_id=mox.IgnoreArg(),
+            retries=mox.IgnoreArg(),
+            raise_errors=mox.IgnoreArg(),
             log_credentials=mox.IgnoreArg(),
             timeout=mox.IgnoreArg(),
         )
@@ -117,6 +121,8 @@ class TestSSL(testtools.TestCase):
             tenant_name=mox.IgnoreArg(),
             token=mox.IgnoreArg(),
             username=mox.IgnoreArg(),
+            retries=mox.IgnoreArg(),
+            raise_errors=mox.IgnoreArg(),
         )
         self.mox.ReplayAll()
 

neutronclient/v2_0/client.py

@@ -129,6 +129,12 @@ class Client(object):
                             http requests. (optional)
     :param bool insecure: SSL certificate validation. (optional)
     :param string ca_cert: SSL CA bundle file to use. (optional)
+    :param integer retries: How many times idempotent (GET, PUT, DELETE)
+                            requests to Neutron server should be retried if
+                            they fail (default: 0).
+    :param bool raise_errors: If True then exceptions caused by connection
+                              failure are propagated to the caller.
+                              (default: True)
 
     Example::
 
@@ -1194,7 +1200,8 @@ class Client(object):
         self.version = '2.0'
         self.format = 'json'
         self.action_prefix = "/v%s" % (self.version)
-        self.retries = 0
+        self.retries = kwargs.get('retries', 0)
+        self.raise_errors = kwargs.get('raise_errors', True)
         self.retry_interval = 1
 
     def _handle_fault_response(self, status_code, response_body):
@@ -1303,8 +1310,16 @@ class Client(object):
                 if i < self.retries:
                     _logger.debug('Retrying connection to Neutron service')
                     time.sleep(self.retry_interval)
+                elif self.raise_errors:
+                    raise
 
-        raise exceptions.ConnectionFailed(reason=_("Maximum attempts reached"))
+        if self.retries:
+            msg = (_("Failed to connect to Neutron server after %d attempts")
+                   % max_attempts)
+        else:
+            msg = _("Failed to connect Neutron server")
+
+        raise exceptions.ConnectionFailed(reason=msg)
 
     def delete(self, action, body=None, headers=None, params=None):
         return self.retry_request("DELETE", action, body=body,