Adding a backcompat warning layer for airflow.settings.MASK_SECRETS_IN_LOGS

[amoghrajesh]

Rare, but there is a chance that folks would use airflow.settings.MASK_SECRETS_IN_LOGS for some reason in their deployments.

This constant has been slayed and moved over to inside the SecretsMasker class now. Although it is not too important, but adding an informational warning for this would probably help.

Earlier:

Python 3.10.18 (main, Sep  8 2025, 22:04:00) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>
>>>
>>>
>>> from airflow.settings
KeyboardInterrupt
>>> import airflow.settings
>>> settings.MASK_SECRETS_IN_LOGS
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'settings' is not defined
>>> airflow.settings.MASK_SECRET_IN_LOGS
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'airflow.settings' has no attribute 'MASK_SECRET_IN_LOGS'
>>> airflow.settings.MASK_SECRETS_IN_LOGS
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'airflow.settings' has no attribute 'MASK_SECRETS_IN_LOGS'
>>> exit()

Now:

root@f6f4a87fe6c4:/opt/airflow# python
Python 3.10.18 (main, Sep  8 2025, 22:04:00) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import airflow.settings
>>> airflow.settings.MASK_SECRETS_IN_LOGS
<stdin>:1 DeprecationWarning: settings.MASK_SECRETS_IN_LOGS has been removed. Use SecretsMasker.enable_log_masking(), disable_log_masking(), or is_log_masking_enabled() instead.
>>> import airflow.settings
KeyboardInterrupt
>>>
KeyboardInterrupt
>>> exit()
root@f6f4a87fe6c4:/opt/airflow# python
Python 3.10.18 (main, Sep  8 2025, 22:04:00) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import airflow.settings
>>> airflow.settings.MASK_SECRETS_IN_LOGS
<stdin>:1 DeprecationWarning: settings.MASK_SECRETS_IN_LOGS has been removed. This shim returns default value of False. Use SecretsMasker.enable_log_masking(), disable_log_masking(), or is_log_masking_enabled() instead.
False

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[amoghrajesh]

I'd like to have this in 3.1 if possible as it is related to a compat thing.