feat(config): read required variables from environment

Overload the `load_defaults` method of logilab.common.configuration to
load REQUIRED variables when the value is specified in the environment.

closes #85

cubicweb/cwconfig.py

@@ -184,7 +184,7 @@ from logilab.common.decorators import cached
 from logilab.common.logging_ext import set_log_methods, init_log
 from logilab.common.configuration import (Configuration, Method,
                                           ConfigurationMixIn, merge_options,
-                                          _validate as lgc_validate)
+                                          _validate as lgc_validate, REQUIRED)
 
 from cubicweb import (CW_SOFTWARE_ROOT, CW_MIGRATION_MAP,
                       ConfigurationError, Binary, _)
@@ -395,8 +395,27 @@ this option is set to yes",
           }),
         )
 
+    def load_defaults(self) -> None:
+        """ overload the parent `load_defaults` to load REQUIRED variables with
+        environment values
+        """
+        for opt, optdict in self.options:
+            action = optdict.get("action")
+            if action != "callback":
+                # callback action have no default
+                default = self.option_default(opt, optdict)
+                if default is REQUIRED:
+                    # the next two lines are different from the parent's method.
+                    # In the parent's, we always continue.
+                    # In this case, we continue only if the value can not be
+                    # read from the environment
+                    default = option_value_from_env(opt)
+                    if default is None:
+                        continue
+                self.set_option(opt, default, action, optdict)
+
     def __getitem__(self, key):
-        """Get configuration option, by first looking at environmnent."""
+        """Get configuration option, by first looking at environment."""
         file_value = super(CubicWebNoAppConfiguration, self).__getitem__(key)
         value = option_value_from_env(key, file_value)
         if value is not None:

cubicweb/test/data/cubicweb_required_variables/__init__.py

+# copyright 2003-2010 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
+#
+# This file is part of CubicWeb.
+#
+# CubicWeb is free software: you can redistribute it and/or modify it under the
+# terms of the GNU Lesser General Public License as published by the Free
+# Software Foundation, either version 2.1 of the License, or (at your option)
+# any later version.
+#
+# CubicWeb is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Lesser General Public License along
+# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.
+"""required variables's __init__
+
+"""

cubicweb/test/data/cubicweb_required_variables/__pkginfo__.py

+# copyright 2003-2010 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
+#
+# This file is part of CubicWeb.
+#
+# CubicWeb is free software: you can redistribute it and/or modify it under the
+# terms of the GNU Lesser General Public License as published by the Free
+# Software Foundation, either version 2.1 of the License, or (at your option)
+# any later version.
+#
+# CubicWeb is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Lesser General Public License along
+# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.
+"""
+
+"""
+distname = "cubicweb-required-variables"
+version = "1.0.0"

cubicweb/test/data/cubicweb_required_variables/site_cubicweb.py

+#!/usr/bin/env python3
+# coding: utf-8
+
+from logilab.common.configuration import REQUIRED
+
+options = (
+    (
+        "a-required-string-option",
+        {
+            "type": "string",
+            "default": REQUIRED,
+            "help": "",
+            "group": "test",
+            "level": 1,
+        },
+    ),
+    (
+        "a-required-int-option",
+        {
+            "type": "int",
+            "default": REQUIRED,
+            "help": "",
+            "group": "test",
+        },
+    ),
+    (
+        "a-required-yn-option",
+        {
+            "type": "yn",
+            "default": REQUIRED,
+            "help": "",
+            "group": "test",
+        },
+    ),
+)

cubicweb/test/unittest_cwconfig.py

@@ -126,6 +126,7 @@ class CubicWebConfigurationTC(BaseTestCase):
             'cubicweb_forge',
             'cubicweb_localperms',
             'cubicweb_mycube',
+            'cubicweb_required_variables',
             'cubicweb_tag',
         ]
         self.assertEqual(self.config.available_cubes(), expected_cubes)
@@ -213,6 +214,35 @@ class CubicWebConfigurationTC(BaseTestCase):
         finally:
             del os.environ['CW_ALLOW_EMAIL_LOGIN']
 
+    def test_config_value_from_environment_required(self):
+        # check that without any variable environment, required options are not
+        # loaded.
+        config = ApptestConfiguration('data', __file__)
+        config._cubes = ('required_variables', )
+        config.load_site_cubicweb()
+
+        self.assertNotIn('a-required-string-option', config)
+        self.assertNotIn('a-required-int-option', config)
+        self.assertNotIn('a-required-yn-option', config)
+
+        # insert the options, and reload the configuration
+        os.environ['CW_A_REQUIRED_STRING_OPTION'] = '42'
+        os.environ['CW_A_REQUIRED_INT_OPTION'] = '42'
+        os.environ['CW_A_REQUIRED_YN_OPTION'] = 'y'
+
+        try:
+            config = ApptestConfiguration('data', __file__)
+            config._cubes = ('required_variables', )
+            config.load_site_cubicweb()
+
+            self.assertEqual(config['a-required-string-option'], '42')
+            self.assertEqual(config['a-required-int-option'], 42)
+            self.assertEqual(config['a-required-yn-option'], True)
+        finally:
+            del os.environ['CW_A_REQUIRED_STRING_OPTION']
+            del os.environ['CW_A_REQUIRED_INT_OPTION']
+            del os.environ['CW_A_REQUIRED_YN_OPTION']
+
 
 class ModnamesTC(unittest.TestCase):