Change default value for [wsgi]/python_interpreter

The default value is being set too early.  We don't want to use
the value of sys.executable at the time the config is generated,
because that's unlikely to map to an existing interpreter in an
actual deployment.

Change-Id: Ic40f582f83e04c6915a3fcb231d6d95ca071c100
Closes-bug: #1962581

glance/async_/flows/plugins/image_conversion.py

@@ -15,6 +15,7 @@
 
 import json
 import os
+import sys
 
 from oslo_concurrency import processutils as putils
 from oslo_config import cfg
@@ -69,7 +70,7 @@ class _ConvertImage(task.Task):
         self.action_wrapper = action_wrapper
         self.image_id = action_wrapper.image_id
         self.dest_path = ""
-        self.python = CONF.wsgi.python_interpreter
+        self.python = CONF.wsgi.python_interpreter or sys.executable
         super(_ConvertImage, self).__init__(
             name='%s-Convert_Image-%s' % (task_type, task_id))
 

glance/common/config.py

@@ -19,7 +19,6 @@ Routines for configuring Glance
 
 import logging
 import os
-import sys
 
 from oslo_config import cfg
 from oslo_middleware import cors
@@ -641,13 +640,13 @@ may overwhelm other system resources such as disk or outbound network
 bandwidth. If this is too small, image import requests will have to wait
 until a thread becomes available to begin processing.""")),
     cfg.StrOpt('python_interpreter',
-               default=sys.executable,
+               default=None,
                help=_("""
 Path to the python interpreter to use when spawning external
-processes. By default this is sys.executable, which should be the
-same interpreter running Glance itself. However, in some situations
-(i.e. uwsgi) this may not actually point to a python interpreter
-itself.""")),
+processes. If left unspecified, this will be sys.executable, which should
+be the same interpreter running Glance itself. However, in some situations
+(for example, uwsgi) sys.executable may not actually point to a python
+interpreter and an alternative value must be set.""")),
 ]
 
 

glance/tests/unit/async_/flows/plugins/test_image_conversion.py

@@ -15,6 +15,7 @@
 
 import json
 import os
+import sys
 from unittest import mock
 
 import glance_store
@@ -264,3 +265,22 @@ class TestConvertImageTask(test_utils.BaseTestCase):
                 os_exists_mock.return_value = True
                 image_convert.revert(result=mock.MagicMock())
                 self.assertEqual(1, mock_os_remove.call_count)
+
+    def test_image_convert_interpreter_resolution(self):
+        # By default, wsgi.python_interpreter is None, which we should
+        # translate to sys.executable at runtime.
+        convert = image_conversion._ConvertImage(self.context,
+                                                 self.task.task_id,
+                                                 self.task_type,
+                                                 self.wrapper)
+        self.assertEqual(sys.executable, convert.python)
+
+        # If overridden, we should take the interpreter from config.
+        fake_interpreter = '/usr/bin/python2.7'
+        self.config(python_interpreter=fake_interpreter,
+                    group='wsgi')
+        convert = image_conversion._ConvertImage(self.context,
+                                                 self.task.task_id,
+                                                 self.task_type,
+                                                 self.wrapper)
+        self.assertEqual(fake_interpreter, convert.python)