
**Apache Airflow version**:
2.0.0

**Environment**:

- **OS** (e.g. from /etc/os-release): Ubuntu 20.04 LTS
- **Python version**: 3.8
- **Kernel** (e.g. `uname -a`): x86_64 x86_64 x86_64 GNU/Linux 5.4.0-58-generic #64-Ubuntu
- **Install tools**: pip


**What happened**:

Airflow 2.0 does not send metrics to statsD.

I configure Airflow with official documentation (https://airflow.apache.org/docs/apache-airflow/stable/logging-monitoring/metrics.html) and by this article https://dstan.medium.com/run-airflow-statsd-grafana-locally-16b372c86524 (but I used port 8125). 

I turned on statsD:

```ini
statsd_on = True
statsd_host = localhost
statsd_port = 8125
statsd_prefix = airflow
```

But I do not see airflow metrics at http://localhost:9102/metrics (statsD metrics endpoint).

---

P.S. I noticed this error just using Airflow 2.0. In version 1.10.13 everything is ok in the same environment.

Thank you for advance.



airflow/stats.py
#
#
#
import logging
import socket
import string
import textwrap
import time
from functools import wraps
from typing import TYPE_CHECKING, Callable, Optional, TypeVar, cast
from airflow.configuration import conf
from airflow.exceptions import AirflowConfigException, InvalidStatsNameException
from airflow.typing_compat import Protocol
log = logging.getLogger(__name__)
class TimerProtocol(Protocol):
    """Type protocol for StatsLogger.timer"""
    def __enter__(self):
        ...
    def __exit__(self, exc_type, exc_value, traceback):
        ...
    def start(self):
        """Start the timer"""
        ...
    def stop(self, send=True):
        """Stop, and (by default) submit the timer to statsd"""
        ...
class StatsLogger(Protocol):