Add basic retries for inspection

A transitory connection failure, such as one caused by
a port being held down for traffic forwarding, can experience
intermittent connectivity failures which result in failed
introspections.

Now the agent retries.

Change-Id: I72c5e3aca000d3854a17f8a461b1a2935e5c0d9b

ironic_python_agent/inspector.py

@@ -24,6 +24,7 @@ from oslo_serialization import jsonutils
 from oslo_utils import excutils
 import requests
 import stevedore
+import tenacity
 
 from ironic_python_agent import config
 from ironic_python_agent import encoding
@@ -115,6 +116,17 @@ def inspect():
     return resp.get('uuid')
 
 
+@tenacity.retry(
+    retry=tenacity.retry_if_exception_type(
+        requests.exceptions.ConnectionError),
+    stop=tenacity.stop_after_attempt(5),
+    wait=tenacity.wait_fixed(5),
+    reraise=True)
+def _post_to_inspector(url, data, verify, cert):
+    return requests.post(CONF.inspection_callback_url, data=data,
+                         verify=verify, cert=cert)
+
+
 def call_inspector(data, failures):
     """Post data to inspector."""
     data['error'] = failures.get_error()
@@ -127,8 +139,8 @@ def call_inspector(data, failures):
     data = encoder.encode(data)
 
     verify, cert = utils.get_ssl_client_options(CONF)
-    resp = requests.post(CONF.inspection_callback_url, data=data,
+    resp = _post_to_inspector(CONF.inspection_callback_url, data=data,
-                         verify=verify, cert=cert)
+                              verify=verify, cert=cert)
     if resp.status_code >= 400:
         LOG.error('inspector %s error %d: %s, proceeding with lookup',
                   CONF.inspection_callback_url,

ironic_python_agent/tests/unit/test_inspector.py

@@ -191,6 +191,15 @@ class TestCallInspector(base.IronicAgentTest):
                                           data='{"data": 42, "error": null}')
         self.assertIsNone(res)
 
+    def test_inspector_retries(self, mock_post):
+        mock_post.side_effect = requests.exceptions.ConnectionError
+        failures = utils.AccumulatedFailures()
+        data = collections.OrderedDict(data=42)
+        self.assertRaises(requests.exceptions.ConnectionError,
+                          inspector.call_inspector,
+                          data, failures)
+        self.assertEqual(5, mock_post.call_count)
+
 
 class BaseDiscoverTest(base.IronicAgentTest):
     def setUp(self):

releasenotes/notes/add-inspection-retry-1d385f69607c1452.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixes an issue where intermittent or transitory connection issues can cause
+    inspection to fail. The ramdisk now retries to report to inspector a total
+    of five times.