**Description**


It would be great if the metrics we publish in Airflow change to include TAGs for "variable" parts of those (such as dag_id, task_id, pool name) rather than being part of the metrics.

See here: https://airflow.apache.org/docs/1.10.12/metrics.html, https://airflow.readthedocs.io/en/latest/logging-monitoring/metrics.html  - those variable parts should be tags.

We might consider to change those metrics by default in 2.0 and possibly introduce a backport in 1.10.13 to allow people to migrate.


**Use case / motivation**

Having the variable parts of the metrics makes it really difficult to aggregate the metrics. Seems that statsd python library does not support tags, but there are possible solutions by installing extensions:

https://stackoverflow.com/questions/49852654/sending-statsd-metrics-with-tags-from-python-client

**Related Issues**

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if self.state == State.RUNNING:
            return
        if self.start_date is None:
            self.log.warning("Failed to record duration of %s: start_date is not set.", self)
            return
        if self.end_date is None:
            self.log.warning("Failed to record duration of %s: end_date is not set.", self)
            return
        duration = self.end_date - self.start_date
        if self.state == State.SUCCESS:
            Stats.timing(f"dagrun.duration.success.{self.dag_id}", duration)
        elif self.state == State.FAILED:
            Stats.timing(f"dagrun.duration.failed.{self.dag_id}", duration)
    @provide_session
    def verify_integrity(self, *, session: Session = NEW_SESSION) -> None: