**Description**

I have noticed that the stable REST API doesn't have the ability to run a task (which is possible from the airflow web interface.
I think it would be nice to have either:
- Run task 
- Run all failing tasks (rerun from point of failure)
this ability for integrations.

**Use case / motivation**

I would like the ability to identify the failing tasks on a specific DAG Run and rerun only them.
I would like to do it remotely (non-interactive) using the REST API.
I could write a script that run only the failing tasks, but I couldn't find a way to "Run" a task, when I have the task instance ID.

**Are you willing to submit a PR?**

Not at this stage

**Related Issues**



airflow/models/dag.py
"""
        Deactivate any DAGs that were last touched by the scheduler before
        the expiration date. These DAGs were likely deleted.
        :param expiration_date: set inactive DAGs that were touched before this
            time
        :type expiration_date: datetime
        :return: None
        """
        for dag in (
            session.query(DagModel)
            .filter(DagModel.last_parsed_time < expiration_date, DagModel.is_active)
            .all()
        ):
            log.info(
                "Deactivating DAG ID %s since it was last touched by the scheduler at %s",
                dag.dag_id,
                dag.last_parsed_time.isoformat(),
            )
            dag.is_active = False
            session.merge(dag)
            session.commit()
    @staticmethod
    @provide_session
    def get_num_task_instances(dag_id, task_ids=None, states=None, session=None):