Source code for lightflow.config
import os
import sys
import ruamel.yaml as yaml
from lightflow.models.exceptions import ConfigLoadError, ConfigFieldError
LIGHTFLOW_CONFIG_ENV = 'LIGHTFLOW_CONFIG'
LIGHTFLOW_CONFIG_NAME = 'lightflow.cfg'
def expand_env_var(env_var):
""" Expands, potentially nested, environment variables.
Args:
env_var (str): The environment variable that should be expanded.
Returns:
str: The fully expanded environment variable.
"""
if not env_var:
return env_var
while True:
interpolated = os.path.expanduser(os.path.expandvars(str(env_var)))
if interpolated == env_var:
return interpolated
else:
env_var = interpolated
[docs]class Config:
""" Hosts the global configuration.
The configuration is read from a structured YAML file or a dictionary.
The location of the file can either be specified directly, is given in
the environment variable LIGHTFLOW_CONFIG_ENV, is looked for in the
current execution directory or in the home directory of the user.
"""
def __init__(self):
self._config = None
[docs] @classmethod
def from_file(cls, filename, *, strict=True):
""" Create a new Config object from a configuration file.
Args:
filename (str): The location and name of the configuration file.
strict (bool): If true raises a ConfigLoadError when the configuration
cannot be found.
Returns:
An instance of the Config class.
Raises:
ConfigLoadError: If the configuration cannot be found.
"""
config = cls()
config.load_from_file(filename, strict=strict)
return config
[docs] def load_from_file(self, filename=None, *, strict=True):
""" Load the configuration from a file.
The location of the configuration file can either be specified directly in the
parameter filename or is searched for in the following order:
1. In the environment variable given by LIGHTFLOW_CONFIG_ENV
2. In the current execution directory
3. In the user's home directory
Args:
filename (str): The location and name of the configuration file.
strict (bool): If true raises a ConfigLoadError when the configuration
cannot be found.
Raises:
ConfigLoadError: If the configuration cannot be found.
"""
self.set_to_default()
if filename:
self._update_from_file(filename)
else:
if LIGHTFLOW_CONFIG_ENV not in os.environ:
if os.path.isfile(os.path.join(os.getcwd(), LIGHTFLOW_CONFIG_NAME)):
self._update_from_file(
os.path.join(os.getcwd(), LIGHTFLOW_CONFIG_NAME))
elif os.path.isfile(expand_env_var('~/{}'.format(LIGHTFLOW_CONFIG_NAME))):
self._update_from_file(
expand_env_var('~/{}'.format(LIGHTFLOW_CONFIG_NAME)))
else:
if strict:
raise ConfigLoadError('Could not find the configuration file.')
else:
self._update_from_file(expand_env_var(os.environ[LIGHTFLOW_CONFIG_ENV]))
self._update_python_paths()
[docs] def load_from_dict(self, conf_dict=None):
""" Load the configuration from a dictionary.
Args:
conf_dict (dict): Dictionary with the configuration.
"""
self.set_to_default()
self._update_dict(self._config, conf_dict)
self._update_python_paths()
[docs] def to_dict(self):
""" Returns a copy of the internal configuration as a dictionary. """
return dict(self._config)
@property
def workflows(self):
""" Return the workflow folders """
return self._config.get('workflows')
@property
def data_store(self):
""" Return the data store settings """
return self._config.get('store')
@property
def signal(self):
""" Return the signal system settings """
return self._config.get('signal')
@property
def logging(self):
""" Return the logging settings """
return self._config.get('logging')
@property
def celery(self):
""" Return the celery settings """
return self._config.get('celery')
@property
def cli(self):
""" Return the cli settings """
return self._config.get('cli')
@property
def extensions(self):
""" Return the custom settings of extensions """
if 'extensions' not in self._config:
raise ConfigFieldError(
'The extensions section is missing in the configuration')
return self._config.get('extensions')
@property
def workflow_polling_time(self):
""" Return the waiting time between status checks of the running dags (sec) """
if 'graph' not in self._config:
raise ConfigFieldError('The graph section is missing in the configuration')
return self._config.get('graph').get('workflow_polling_time')
@property
def dag_polling_time(self):
""" Return the waiting time between status checks of the running tasks (sec) """
if 'graph' not in self._config:
raise ConfigFieldError('The graph section is missing in the configuration')
return self._config.get('graph').get('dag_polling_time')
[docs] def set_to_default(self):
""" Overwrite the configuration with the default configuration. """
self._config = yaml.safe_load(self.default())
def _update_from_file(self, filename):
""" Helper method to update an existing configuration with the values from a file.
Loads a configuration file and replaces all values in the existing configuration
dictionary with the values from the file.
Args:
filename (str): The path and name to the configuration file.
"""
if os.path.exists(filename):
try:
with open(filename, 'r') as config_file:
yaml_dict = yaml.safe_load(config_file.read())
if yaml_dict is not None:
self._update_dict(self._config, yaml_dict)
except IsADirectoryError:
raise ConfigLoadError(
'The specified configuration file is a directory not a file')
else:
raise ConfigLoadError('The config file {} does not exist'.format(filename))
def _update_dict(self, to_dict, from_dict):
""" Recursively merges the fields for two dictionaries.
Args:
to_dict (dict): The dictionary onto which the merge is executed.
from_dict (dict): The dictionary merged into to_dict
"""
for key, value in from_dict.items():
if key in to_dict and isinstance(to_dict[key], dict) and \
isinstance(from_dict[key], dict):
self._update_dict(to_dict[key], from_dict[key])
else:
to_dict[key] = from_dict[key]
def _update_python_paths(self):
""" Append the workflow and libraries paths to the PYTHONPATH. """
for path in self._config['workflows'] + self._config['libraries']:
if os.path.isdir(os.path.abspath(path)):
if path not in sys.path:
sys.path.append(path)
else:
raise ConfigLoadError(
'Workflow directory {} does not exist'.format(path))
[docs] @staticmethod
def default():
""" Returns the default configuration. """
return '''
workflows:
- ./examples
libraries: []
celery:
broker_url: redis://localhost:6379/0
result_backend: redis://localhost:6379/0
worker_concurrency: 8
result_expires: 0
worker_send_task_events: True
worker_prefetch_multiplier: 1
signal:
host: localhost
port: 6379
password: null
database: 0
polling_time: 0.5
store:
host: localhost
port: 27017
database: lightflow
username: null
password: null
auth_source: admin
auth_mechanism: null
connect_timeout: 30000
graph:
workflow_polling_time: 0.5
dag_polling_time: 0.5
cli:
time_format: '%d/%m/%Y %H:%M:%S'
extensions: {}
logging:
version: 1
disable_existing_loggers: false
formatters:
verbose:
format: '[%(asctime)s][%(levelname)s] %(name)s %(filename)s:%(funcName)s:%(lineno)d | %(message)s'
datefmt: '%d/%m/%Y %H:%M:%S'
simple:
(): 'colorlog.ColoredFormatter'
format: '%(log_color)s[%(asctime)s][%(levelname)s] %(blue)s%(processName)s%(reset)s | %(message)s'
datefmt: '%d/%m/%Y %H:%M:%S'
handlers:
console:
class: logging.StreamHandler
level: INFO
formatter: simple
loggers:
celery:
handlers:
- console
level: INFO
root:
handlers:
- console
level: INFO
'''