JSON serialize Log extras

[joshowen]

It would be very useful to be able to query the the logged extras, to determine if a trigger has a configuration, or a clear operation is confirmed.

---

Make sure to mark the boxes below before creating PR: [x]

• Description above provides context of the change
• Unit tests coverage for changes (not needed for documentation changes)
• Target Github ISSUE in description if exists
• Commits follow "How to write a good git commit message"
• Relevant documentation is updated including usage instructions.
• I will engage committers as explained in Contribution Workflow Example.

---

In case of fundamental code change, Airflow Improvement Proposal (AIP) is needed.
In case of a new dependency, check compliance with the ASF 3rd Party License Policy.
In case of backwards incompatible changes please leave a note in UPDATING.md.
Read the Pull Request Guidelines for more information.

[boring-cyborg]

Congratulations on your first Pull Request and welcome to the Apache Airflow community! If you have any issues or are unsure about any anything please check our Contribution Guide (https://github.com/apache/airflow/blob/master/CONTRIBUTING.rst)
Here are some useful points:

• Pay attention to the quality of your code (flake8, pylint and type annotations). Our pre-commits will help you with that.
• In case of a new feature add useful documentation (in docstrings or in docs/ directory). Adding a new operator? Check this short guide Consider adding an example DAG that shows how users should use it.
• Consider using Breeze environment for testing locally, it’s a heavy docker but it ships with a working Airflow and a lot of integrations.
• Be patient and persistent. It might take some time to get a review or get the final approval from Committers.
• Be sure to read the Airflow Coding style.
  Apache Airflow is a community-driven project and together we are making it better 🚀.
  In case of doubts contact the developers at:
  Mailing List: dev@airflow.apache.org
  Slack: https://apache-airflow-slack.herokuapp.com/

[kaxil]

Why not fetch str and handle serialization on the client-side?

[joshowen]

The current setup doesn't produce valid json, because it is a list of tuples. It would also be very helpful to be able to query this information in the database, since important context lives in the extra, eg whether or not a clear was confirmed, or a trigger had a conf.

[joshowen]

@kaxil to give more color, we've built an "Airflow Snitch" which alerts based on some user actions (eg user cleared a production DAG). This relies on parsing the extra field to determine if the job was actually cleared since there are two trigger events, and only the confirmed event causes an action.

We've hacked together some extra field parsing, but it isn't very elegant, and this could be done a lot more efficiently in the database if the column was valid json.

[kaxil]

Thanks for the explanation, can you add a test, please

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.