Change the log level for "Variable not found" from error to debug when a default is provided.

[vanchaxy]

Description

Change the log level for "Variable not found" from error to debug when a default is provided.

Use case/motivation

I'm testing migration to Airflow 3 and have noticed a lot of errors in the logs. The problem is that Airflow logs errors when a variable is not found, even if a default is provided.

In our use case, we have 100+ DAGs and use variables to configure schedules for them, so variables are read during DAG loading. This leads to significant error log spam that is picked up by Sentry. It's possible to work around this with custom logging filters, but I believe using the error log level is suboptimal and should be changed in Airflow core, especially considering Variable.get supports the "default" kwarg.

Related issues

No response

Are you willing to submit a PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct

[potiuk]

Marked it as good first issue for someone to pick up -> but maybe you would like to take a stab on it and contribute it yourself @vanchaxy. It does not sem difficult to do, and we always welcome new contributors.

[pradyumnac26]

Here's my PR for the above issue. #52846
@potiuk please review :) .