Add support for dag_stats in REST API

[reganbaum]

Description

1. Today, there is no REST API available to get the stats of a DAG (# success/failed/running/queued runs) via API. However, the UI uses an endpoint dag_stats to display this information. The goal is to have a REST API endpoint available that gets the DAG stats at /api/v1/dag_stats.
2. Moved over to Add support for dagrun_failed in REST API #40600

Use case/motivation

I would like to programmatically (1) get the stats for all my DAGs and (2) programmatically stop a running workflow, which actually stops the execution (not just changes the state in the database).

Related issues

#40600

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]

(1) - sure if someone implements it
(2) - impossible until we change architecture (possibly might be doable in Airlfow 3 - I heartily invite you to subscribe to devlist discussions on that and take part in those discussions and advocate and possibly offer contributions to make it happen

[potiuk]

Marked it for (1) as "good first issue" and if someone would like to implement such endpoint. Also @reganbaum you are welcome to try it if you want to have it faster rather than wait for someone to pick it up and implement.

[reganbaum]

Thanks, Jarek. I moved the dagrun_failed issue (2) over to its own issue for easier tracking: #40600

[dondaum]

Happy to take this over. Would be a good chance to get to know the Airflow REST API.

[potiuk]

Assigned you