Params Definition is Required to be JSON Schema Valid also if Manually Triggered #31299

Apache Airflow version

2.6.0

What happened

While trying to debug other things I stumbled over the function DAG.validate_schedule_and_params() which is used in the constructor of the DAG class. This function validates all DAG params for JSON Schema correctness - but only if the trigger condition is not set to manual. From point of code I understood that this is made especially to have a valid DAG but validate params at time of triggering.

I tried to apply this as a "feature" in the Trigger UI Forms from AIP-50 and realized that DAG parsing in dagbag.py:444 calls dag.validate() which still does a full validation. So the DAG can not be rendered if params are not valid against JSON Schema.

What you think should happen instead

So if we have a manual triggered DAG it would be cool to relax param validation and check on submission. This would allow to define required fields and enforce a user to prove content w/o having a default and the user just hits "Trigger".

Besides this it makes the constructor and the dag.validate() call consistent in regards of checks.

How to reproduce

Run your Airflow instance and edit airflow/example_dags/example_params_ui_tutorial.py in line 108 for example and set the default value of required_field to None. You will get a DAG parsing error even the DAG is manually triggered.

Operating System

Ubuntu 20.04

Versions of Apache Airflow Providers

defaults

Deployment

Official Apache Airflow Helm Chart

Deployment details

Standard Docker deployment of Airflow 2.6.0

Anything else

No response

Are you willing to submit PR?

• Yes I am willing to submit a PR!

Code of Conduct

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