Source code for airflow.models.variable

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import json
import logging
import os
from typing import Any, Optional

from cryptography.fernet import InvalidToken as InvalidFernetToken
from sqlalchemy import Boolean, Column, Integer, String, Text
from sqlalchemy.ext.declarative import declared_attr
from sqlalchemy.orm import Session, reconstructor, synonym

from airflow.configuration import ensure_secrets_loaded
from airflow.models.base import ID_LEN, Base
from airflow.models.crypto import get_fernet
from airflow.utils.log.logging_mixin import LoggingMixin
from airflow.utils.log.secrets_masker import mask_secret
from airflow.utils.session import provide_session

[docs]log = logging.getLogger()
[docs]class Variable(Base, LoggingMixin): """ Variables are a generic way to store and retrieve arbitrary content or settings as a simple key value store within Airflow. """
[docs] __tablename__ = "variable"
[docs] __NO_DEFAULT_SENTINEL = object()
[docs] id = Column(Integer, primary_key=True)
[docs] key = Column(String(ID_LEN), unique=True)
[docs] _val = Column('val', Text)
[docs] description = Column(Text)
[docs] is_encrypted = Column(Boolean, unique=False, default=False)
def __init__(self, key=None, val=None, description=None): super().__init__() self.key = key self.val = val self.description = description @reconstructor
[docs] def on_db_load(self): # pylint: disable=missing-function-docstring if self._val: mask_secret(self.val, self.key)
[docs] def __repr__(self): # Hiding the value return f'{self.key} : {self._val}'
[docs] def get_val(self): """Get Airflow Variable from Metadata DB and decode it using the Fernet Key""" if self._val is not None and self.is_encrypted: try: fernet = get_fernet() return fernet.decrypt(bytes(self._val, 'utf-8')).decode() except InvalidFernetToken: self.log.error("Can't decrypt _val for key=%s, invalid token or value", self.key) return None except Exception: # pylint: disable=broad-except self.log.error("Can't decrypt _val for key=%s, FERNET_KEY configuration missing", self.key) return None else: return self._val
[docs] def set_val(self, value): """Encode the specified value with Fernet Key and store it in Variables Table.""" if value is not None: fernet = get_fernet() self._val = fernet.encrypt(bytes(value, 'utf-8')).decode() self.is_encrypted = fernet.is_encrypted
[docs] def val(cls): # pylint: disable=no-self-argument """Get Airflow Variable from Metadata DB and decode it using the Fernet Key""" return synonym('_val', descriptor=property(cls.get_val, cls.set_val))
[docs] def setdefault(cls, key, default, deserialize_json=False): """ Like a Python builtin dict object, setdefault returns the current value for a key, and if it isn't there, stores the default value and returns it. :param key: Dict key for this Variable :type key: str :param default: Default value to set and return if the variable isn't already in the DB :type default: Mixed :param deserialize_json: Store this as a JSON encoded value in the DB and un-encode it when retrieving a value :return: Mixed """ obj = Variable.get(key, default_var=None, deserialize_json=deserialize_json) if obj is None: if default is not None: Variable.set(key, default, serialize_json=deserialize_json) return default else: raise ValueError('Default Value must be set') else: return obj
[docs] def get( cls, key: str, default_var: Any = __NO_DEFAULT_SENTINEL, deserialize_json: bool = False, ) -> Any: """ Gets a value for an Airflow Variable Key :param key: Variable Key :param default_var: Default value of the Variable if the Variable doesn't exists :param deserialize_json: Deserialize the value to a Python dict """ var_val = Variable.get_variable_from_secrets(key=key) if var_val is None: if default_var is not cls.__NO_DEFAULT_SENTINEL: return default_var else: raise KeyError(f'Variable {key} does not exist') else: if deserialize_json: obj = json.loads(var_val) mask_secret(var_val, key) return obj else: mask_secret(var_val, key) return var_val
@classmethod @provide_session
[docs] def set(cls, key: str, value: Any, serialize_json: bool = False, session: Session = None): """ Sets a value for an Airflow Variable with a given Key :param key: Variable Key :param value: Value to set for the Variable :param serialize_json: Serialize the value to a JSON string :param session: SQL Alchemy Sessions """ env_var_name = "AIRFLOW_VAR_" + key.upper() if env_var_name in os.environ: log.warning( "You have the environment variable %s defined, which takes precedence over reading " "from the database. The value will be saved, but to read it you have to delete " "the environment variable.", env_var_name, ) if serialize_json: stored_value = json.dumps(value, indent=2) else: stored_value = str(value) Variable.delete(key, session=session) session.add(Variable(key=key, val=stored_value)) session.flush()
@classmethod @provide_session
[docs] def delete(cls, key: str, session: Session = None) -> int: """ Delete an Airflow Variable for a given key :param key: Variable Key :param session: SQL Alchemy Sessions """ return session.query(cls).filter(cls.key == key).delete()
[docs] def rotate_fernet_key(self): """Rotate Fernet Key""" fernet = get_fernet() if self._val and self.is_encrypted: self._val = fernet.rotate(self._val.encode('utf-8')).decode()
[docs] def get_variable_from_secrets(key: str) -> Optional[str]: """ Get Airflow Variable by iterating over all Secret Backends. :param key: Variable Key :return: Variable Value """ for secrets_backend in ensure_secrets_loaded(): var_val = secrets_backend.get_variable(key=key) if var_val is not None: return var_val return None

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