Source code for airflow.models.variable

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from __future__ import annotations

import json
import logging
from typing import Any

from sqlalchemy import Boolean, Column, Integer, String, Text
from sqlalchemy.dialects.mysql import MEDIUMTEXT
from sqlalchemy.orm import Session, declared_attr, reconstructor, synonym

from airflow.api_internal.internal_api_call import internal_api_call
from airflow.configuration import ensure_secrets_loaded
from airflow.models.base import ID_LEN, Base
from airflow.models.crypto import get_fernet
from airflow.secrets.metastore import MetastoreBackend
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(__name__)
[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] id = Column(Integer, primary_key=True)
[docs] key = Column(String(ID_LEN), unique=True)
_val = Column("val", Text().with_variant(MEDIUMTEXT, "mysql"))
[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): 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""" from cryptography.fernet import InvalidToken as InvalidFernetToken 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: 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): """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, description=None, 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 :param default: Default value to set and return if the variable isn't already in the DB :param description: Default value to set Description of the Variable :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, description=description, 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 exist :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
@staticmethod @provide_session @internal_api_call
[docs] def set( key: str, value: Any, description: str | None = None, serialize_json: bool = False, session: Session = None, ): """ Sets a value for an Airflow Variable with a given Key. This operation will overwrite an existing variable. :param key: Variable Key :param value: Value to set for the Variable :param description: Description of the Variable :param serialize_json: Serialize the value to a JSON string :param session: SQL Alchemy Sessions """ # check if the secret exists in the custom secrets' backend. Variable.check_for_write_conflict(key) 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, description=description)) session.flush()
@staticmethod @provide_session @internal_api_call
[docs] def update( key: str, value: Any, serialize_json: bool = False, session: Session = None, ): """ Updates a given Airflow Variable with the Provided value :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 Session """ Variable.check_for_write_conflict(key) if Variable.get_variable_from_secrets(key=key) is None: raise KeyError(f"Variable {key} does not exist") obj = session.query(Variable).filter(Variable.key == key).first() if obj is None: raise AttributeError(f"Variable {key} does not exist in the Database and cannot be updated.") Variable.set(key, value, description=obj.description, serialize_json=serialize_json)
@staticmethod @provide_session @internal_api_call
[docs] def delete(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(Variable).filter(Variable.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 check_for_write_conflict(key: str) -> None: """ Logs a warning if a variable exists outside of the metastore. If we try to write a variable to the metastore while the same key exists in an environment variable or custom secrets backend, then subsequent reads will not read the set value. :param key: Variable Key """ for secrets_backend in ensure_secrets_loaded(): if not isinstance(secrets_backend, MetastoreBackend): try: var_val = secrets_backend.get_variable(key=key) if var_val is not None: log.warning( "The variable {key} is defined in the {cls} secrets backend, which takes " "precedence over reading from the database. The value in the database will be " "updated, but to read it you have to delete the conflicting variable " "from {cls}".format(key=key, cls=secrets_backend.__class__.__name__) ) return except Exception: log.exception( "Unable to retrieve variable from secrets backend (%s). " "Checking subsequent secrets backend.", type(secrets_backend).__name__, ) return None
[docs] def get_variable_from_secrets(key: str) -> str | None: """ Get Airflow Variable by iterating over all Secret Backends. :param key: Variable Key :return: Variable Value """ for secrets_backend in ensure_secrets_loaded(): try: var_val = secrets_backend.get_variable(key=key) if var_val is not None: return var_val except Exception: log.exception( "Unable to retrieve variable from secrets backend (%s). " "Checking subsequent secrets backend.", type(secrets_backend).__name__, ) return None

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