airflow-core/docs/howto/variable.rst

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.. _managing_variables:

Managing Variables
==================

Variables are a generic way to store and retrieve arbitrary content or
settings as a simple key value store within Airflow. Variables can be
listed, created, updated and deleted from the UI (``Admin -> Variables``),
code or CLI.

.. image:: ../img/ui-dark/variable_hidden.png

See the :doc:`Variables Concepts </core-concepts/variables>` documentation for
more information.

Storing Variables in Environment Variables
------------------------------------------

.. versionadded:: 1.10.10

Airflow Variables can also be created and managed using Environment Variables. The environment variable
naming convention is :envvar:`AIRFLOW_VAR_{VARIABLE_NAME}`, all uppercase.
So if your variable key is ``foo`` then the variable name should be ``AIRFLOW_VAR_FOO``.

For example,

.. code-block:: bash

    export AIRFLOW_VAR_FOO=BAR

    # To use JSON, store them as JSON strings
    export AIRFLOW_VAR_FOO_BAZ='{"hello":"world"}'

You can use them in your Dags as:

.. code-block:: python

    from airflow.sdk import Variable

    foo = Variable.get("foo")
    foo_json = Variable.get("foo_baz", deserialize_json=True)

.. note::

    Single underscores surround ``VAR``.  This is in contrast with the way ``airflow.cfg``
    parameters are stored, where double underscores surround the config section name.
    Variables set using Environment Variables will also
    take precedence over variables defined in the Airflow UI.

Visibility in UI and CLI
^^^^^^^^^^^^^^^^^^^^^^^^^

Variables defined through environment variables are **not displayed** in the Airflow UI or listed using ``airflow variables list``.

This is because these variables are **resolved dynamically at runtime**, typically on the **worker** process executing your task. They are not stored in the metadata database or loaded in the webserver or scheduler environment.

This supports secure deployment patterns where environment-based secrets (e.g. via ``.env`` files, Docker, or Kubernetes secrets) are injected only into runtime components like workers — and not into components exposed to users, like the webserver.

If you want variables to appear in the UI for visibility or editing, define them in the metadata database instead.

Securing Variables
------------------

Airflow uses `Fernet <https://github.com/fernet/spec/>`__ to encrypt variables stored in the metastore database.
It guarantees that without the encryption password, content cannot be manipulated or read
without the key. For information on configuring Fernet, look at :ref:`security/fernet`.

In addition to retrieving variables from environment variables or the metastore database, you can enable
a secrets backend to retrieve variables. For more details see :doc:`/security/secrets/secrets-backend/index`.