**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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pass  
                elif self.state != State.RUNNING and not dag.partial:
                    self.log.warning("Failed to get task '%s' for dag '%s'. Marking it as removed.", ti, dag)
                    Stats.incr(f"task_removed_from_dag.{dag.dag_id}", 1, 1)
                    ti.state = State.REMOVED
                continue
            try:
                num_mapped_tis = task.get_parse_time_mapped_ti_count()
            except NotMapped:
                continue
            except NotFullyPopulated:
                
                try:
                    total_length = task.get_mapped_ti_count(self.run_id, session=session)
                except NotFullyPopulated:
                    
                    if ti.map_index >= 0:
                        self.log.debug(
                            "Removing the unmapped TI '%s' as the mapping can't be resolved yet", ti
                        )
                        ti.state = State.REMOVED
                    continue
                
                if ti.map_index >= total_length:
                    self.log.debug(
                        "Removing task '%s' as the map_index is longer than the resolved mapping list (%d)",
                        ti,
                        total_length,
                    )
                    ti.state = State.REMOVED