import os
import configparser
[docs]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.
It 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, conf_file_name, default_conf, command_line_conf):
self.data_dir = data_dir
self.conf_file_path = os.path.join(self.data_dir, conf_file_name)
self.conf_fields = default_conf
self.command_line_conf = command_line_conf
self.overwritten_fields = set()
[docs] def build_config(self):
"""
Builds a config dictionary from command line, config file and default configuration parameters.
The priority is 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)
# Load parameters and cast them to int if necessary
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:
try:
self.conf_fields[k_upper]["value"] = int(v)
except ValueError:
err_msg = "{} is not an integer ({}).".format(k, v)
raise ValueError(err_msg)
else:
self.conf_fields[k_upper]["value"] = v
self.overwritten_fields.add(k_upper)
# 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
self.overwritten_fields.add(k)
# Extend relative paths
expanded_data_dir = self.extend_paths()
# Sanity check fields and build config dictionary
config = self.create_config_dict()
config["DATA_DIR"] = expanded_data_dir
return config
[docs] 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`` are 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 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
[docs] def extend_paths(self):
"""
Extends the relative paths of the ``conf_fields`` dictionary with ``data_dir``.
If an absolute path is given, it will remain the same.
If the config contains a BTC_NETWORK field whose value is not "mainnet", it is also appended to the path.
"""
# if there is a BTC_NETWORK parameter whose value is not "mainnet", we append it to the data_dir when expanding
network_field = self.conf_fields.get("BTC_NETWORK")
if network_field and network_field.get("value") != "mainnet":
expanded_data_dir = os.path.join(self.data_dir, network_field.get("value"))
else:
expanded_data_dir = self.data_dir
for key, field in self.conf_fields.items():
if field.get("path") and isinstance(field.get("value"), str):
self.conf_fields[key]["value"] = os.path.join(expanded_data_dir, self.conf_fields[key]["value"])
return expanded_data_dir