1 files changed, 115 insertions, 0 deletions
diff --git a/src/onapsdk/configuration/loader.py b/src/onapsdk/configuration/loader.py
new file mode 100644
index 0000000..a9aae6f
--- /dev/null
+++ b/src/onapsdk/configuration/loader.py
@@ -0,0 +1,115 @@
+"""Settings loader module."""
+#   Copyright 2022 Orange, Deutsche Telekom AG
+#
+#   Licensed under the Apache License, Version 2.0 (the "License");
+#   you may not use this file except in compliance with the License.
+#   You may obtain a copy of the License at
+#
+#       http://www.apache.org/licenses/LICENSE-2.0
+#
+#   Unless required by applicable law or agreed to in writing, software
+#   distributed under the License is distributed on an "AS IS" BASIS,
+#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#   See the License for the specific language governing permissions and
+#   limitations under the License.
+import importlib
+import os
+from typing import Any
+
+from onapsdk.exceptions import ModuleError, SettingsError
+
+from . import global_settings
+
+
+SETTINGS_ENV = "ONAP_PYTHON_SDK_SETTINGS"
+
+
+class SettingsLoader:
+    """Settings loader class.
+
+    Load global settings and optionally load
+        custom settings by importing the module
+        stored in ONAP_PYTHON_SDK_SETTINGS environment
+        variable.
+        The module has to be uder PYTHONPATH.
+    """
+
+    def __init__(self) -> None:
+        """Load settings.
+
+        Load global settings and optionally load custom one.
+
+        Raises:
+            ModuleError: If ONAP_PYTHON_SDK_SETTINGS environment variable
+                is set and module can't be imported.
+
+        """
+        self._settings = {}
+
+        # Load values from global_settings (only uppercase)
+        self.filter_and_set(global_settings)
+
+        settings_env_value: str = os.environ.get(SETTINGS_ENV)
+        if settings_env_value:
+            # Load values from custom settings
+            try:
+                module = importlib.import_module(settings_env_value)
+            except ModuleNotFoundError:
+                msg = "Can't import custom settings. Is it under PYTHONPATH?"
+                raise ModuleError(msg)
+            self.filter_and_set(module)
+
+    def __getattribute__(self, name: str) -> Any:
+        """Return stored attributes.
+
+        If attribute name is uppercase return it from
+            _settings dictionary.
+            Look for attribute in __dict__ otherwise.
+
+        Args:
+            name (str): Attribute's name
+
+        Raises:
+            SettingsError: a setting is not found by the key.
+
+        Returns:
+            Any: Attribute's value
+
+        """
+        if name.isupper():
+            try:
+                return self._settings[name]
+            except KeyError as exc:
+                msg = f"Requested setting {exc.args[0]} does not exist."
+                raise SettingsError(msg) from exc
+        return super().__getattribute__(name)
+
+    def __setattr__(self, name: str, value: Any) -> None:
+        """Save attribute.
+
+        If attribute name is uppercase save the value
+            in _settings dictionary.
+            Use Object class __setattr__ implementation
+            otherwise.
+
+        Args:
+            name (str): Attribute's name
+            value (Any): Attribute's value
+
+        """
+        if name.isupper():
+            self._settings[name] = value
+        super().__setattr__(name, value)
+
+    def filter_and_set(self, module: "module") -> None:
+        """Filter module attributes and save the uppercased.
+
+        Iterate through module's attribures and save the value
+            of them which name is uppercase.
+
+        Args:
+            module (module): Module to get attributes from
+
+        """
+        for key in filter(lambda x: x.isupper(), dir(module)):
+            self._settings[key] = getattr(module, key)