Adds ConfigLoader to handle loading configurations parameters. Switches from conf.py to .conf files

common/config_loader.py

@@ -0,0 +1,101 @@
+import os
+import configparser
+
+from common.tools import extend_paths
+
+
+class ConfigLoader:
+    """
+     The :class:`ConfigLoader` class is in charge of loading all the configuration parameters to create a config dict
+     that can be used to set all configurable parameters of the system.
+
+    Args:
+        data_dir (:obj:`str`): the path to the data directory where the configuration file may be found.
+        default_conf (:obj:`dict`): a dictionary populated with the default configuration params and the expected types.
+            The format is as follows:
+
+            {"field0": {"value": value_from_conf_file, "type": expected_type, ...}}
+
+        command_line_conf (:obj:`dict`): a dictionary containing the command line parameters that may replace the
+            ones in default / config file.
+
+    Attributes:
+        data_dir (:obj:`str`): the path to the data directory where the configuration file may be found.
+        conf_file_path (:obj:`str`): the path to the config file (the file may not exist).
+        conf_fields (:obj:`dict`): a dictionary populated with the configuration params and the expected types.
+            follows the same format as default_conf.
+        command_line_conf (:obj:`dict`): a dictionary containing the command line parameters that may replace the
+            ones in default / config file.
+    """
+
+    def __init__(self, data_dir, default_conf, command_line_conf):
+        self.data_dir = data_dir
+        self.conf_file_path = self.data_dir + "teos.conf"
+        self.conf_fields = default_conf
+        self.command_line_conf = command_line_conf
+
+    def build_config(self):
+        """
+        Builds a config dictionary from command line, config file and default configuration parameters.
+
+        The priority if as follows:
+            - command line
+            - config file
+            - defaults
+
+        Returns:
+            obj:`dict`: a dictionary containing all the configuration parameters.
+
+        """
+
+        if os.path.exists(self.conf_file_path):
+            file_config = configparser.ConfigParser()
+            file_config.read(self.conf_file_path)
+
+            if file_config:
+                for sec in file_config.sections():
+                    for k, v in file_config.items(sec):
+                        k_upper = k.upper()
+                        if k_upper in self.conf_fields:
+                            if self.conf_fields[k_upper]["type"] == int:
+                                self.conf_fields[k_upper]["value"] = int(v)
+                            else:
+                                self.conf_fields[k_upper]["value"] = v
+
+        # Override the command line parameters to the defaults / conf file
+        for k, v in self.command_line_conf.items():
+            self.conf_fields[k]["value"] = v
+
+        # Extend relative paths
+        extend_paths(self.data_dir, self.conf_fields)
+
+        # Sanity check fields and build config dictionary
+        config = self.create_config_dict()
+
+        return config
+
+    def create_config_dict(self):
+        """
+        Checks that the configuration fields (self.conf_fields) have the right type and creates a config dict if so.
+
+        Returns:
+            :obj:`dict`: A dictionary with the same keys as the provided one, but containing only the "value" field as
+            value if the provided ``conf_fields`` where correct.
+
+        Raises:
+            ValueError: If any of the dictionary elements does not have the expected type
+        """
+
+        conf_dict = {}
+
+        for field in self.conf_fields:
+            value = self.conf_fields[field]["value"]
+            correct_type = self.conf_fields[field]["type"]
+
+            if (value is not None) and isinstance(value, correct_type):
+                conf_dict[field] = value
+            else:
+                err_msg = "{} variable in config is of the wrong type".format(field)
+                raise ValueError(err_msg)
+
+        return conf_dict