From 7edf7ff66dd16d716c7b4935738ccb15f0a83aaf Mon Sep 17 00:00:00 2001
From: jiangpch <jiangpengcheng@navercorp.com>
Date: Sun, 22 Oct 2017 23:17:35 -0400
Subject: [PATCH] Refactor exception handling in cmd.api

Replace the known exception tuple with a map of exception classes
to error codes to preserve backward compatibility of exit codes.
Also change the code to handle unknown members of the Exception
hierarchy without breaking.

Co-authored-by: jiangpch <jiangpengcheng@navercorp.com>
Co-authored-by: Brian Rosmaita <rosmaita.fossdev@gmail.com>

Closes-Bug: #1726213

Change-Id: Iabfc2ded45a576a18bdb30a6c3ada8b9799a3196
---
 glance/cmd/api.py                 | 17 +++++----
 glance/tests/unit/api/test_cmd.py | 58 +++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+), 7 deletions(-)

diff --git a/glance/cmd/api.py b/glance/cmd/api.py
index 4ff5071288..89fe1b730b 100644
--- a/glance/cmd/api.py
+++ b/glance/cmd/api.py
@@ -56,16 +56,19 @@ CONF = cfg.CONF
 CONF.import_group("profiler", "glance.common.wsgi")
 logging.register_options(CONF)
 
-KNOWN_EXCEPTIONS = (RuntimeError,
-                    exception.WorkerCreationFailure,
-                    glance_store.exceptions.BadStoreConfiguration,
-                    ValueError)
+# NOTE(rosmaita): Any new exceptions added should preserve the current
+# error codes for backward compatibility.  The value 99 is returned
+# for errors not listed in this map.
+ERROR_CODE_MAP = {RuntimeError: 1,
+                  exception.WorkerCreationFailure: 2,
+                  glance_store.exceptions.BadStoreConfiguration: 3,
+                  ValueError: 4,
+                  cfg.ConfigFileValueError: 5}
 
 
 def fail(e):
-    global KNOWN_EXCEPTIONS
-    return_code = KNOWN_EXCEPTIONS.index(type(e)) + 1
     sys.stderr.write("ERROR: %s\n" % encodeutils.exception_to_unicode(e))
+    return_code = ERROR_CODE_MAP.get(type(e), 99)
     sys.exit(return_code)
 
 
@@ -89,7 +92,7 @@ def main():
         server = wsgi.Server(initialize_glance_store=True)
         server.start(config.load_paste_app('glance-api'), default_port=9292)
         server.wait()
-    except KNOWN_EXCEPTIONS as e:
+    except Exception as e:
         fail(e)
 
 
diff --git a/glance/tests/unit/api/test_cmd.py b/glance/tests/unit/api/test_cmd.py
index 3582da0fab..21da156f3d 100644
--- a/glance/tests/unit/api/test_cmd.py
+++ b/glance/tests/unit/api/test_cmd.py
@@ -132,3 +132,61 @@ class TestGlanceApiCmd(test_utils.BaseTestCase):
                        self._raise(RuntimeError))
         exit = self.assertRaises(SystemExit, glance.cmd.cache_pruner.main)
         self.assertEqual('ERROR: ', exit.code)
+
+    def test_fail_with_value_error(self):
+        with mock.patch('sys.stderr.write') as mock_stderr:
+            with mock.patch('sys.exit') as mock_exit:
+                exc_msg = 'A ValueError, LOL!'
+                exc = ValueError(exc_msg)
+                glance.cmd.api.fail(exc)
+                mock_stderr.assert_called_once_with('ERROR: %s\n' % exc_msg)
+                mock_exit.assert_called_once_with(4)
+
+    def test_fail_with_config_exception(self):
+        with mock.patch('sys.stderr.write') as mock_stderr:
+            with mock.patch('sys.exit') as mock_exit:
+                exc_msg = 'A ConfigError by George!'
+                exc = cfg.ConfigFileValueError(exc_msg)
+                glance.cmd.api.fail(exc)
+                mock_stderr.assert_called_once_with('ERROR: %s\n' % exc_msg)
+                mock_exit.assert_called_once_with(5)
+
+    def test_fail_with_unknown_exception(self):
+        with mock.patch('sys.stderr.write') as mock_stderr:
+            with mock.patch('sys.exit') as mock_exit:
+                exc_msg = 'A Crazy Unkown Error.'
+                exc = CrayCray(exc_msg)
+                glance.cmd.api.fail(exc)
+                mock_stderr.assert_called_once_with('ERROR: %s\n' % exc_msg)
+                mock_exit.assert_called_once_with(99)
+
+    def test_main_with_store_config_exception(self):
+        with mock.patch.object(glance.common.config,
+                               'parse_args') as mock_config:
+            with mock.patch('sys.exit') as mock_exit:
+                exc = store.exceptions.BadStoreConfiguration()
+                mock_config.side_effect = exc
+                glance.cmd.api.main()
+                mock_exit.assert_called_once_with(3)
+
+    def test_main_with_runtime_error(self):
+        with mock.patch.object(glance.common.config,
+                               'parse_args') as mock_config:
+            with mock.patch('sys.exit') as mock_exit:
+                exc = RuntimeError()
+                mock_config.side_effect = exc
+                glance.cmd.api.main()
+                mock_exit.assert_called_once_with(1)
+
+    def test_main_with_worker_creation_failure(self):
+        with mock.patch.object(glance.common.config,
+                               'parse_args') as mock_config:
+            with mock.patch('sys.exit') as mock_exit:
+                exx = exc.WorkerCreationFailure()
+                mock_config.side_effect = exx
+                glance.cmd.api.main()
+                mock_exit.assert_called_once_with(2)
+
+
+class CrayCray(Exception):
+    pass