Apache Airflow initdb command fails, due to syntax error - airflow

Question

I have created virtualenv for python3 using:
virtualenv -p $(which python3) ENV
Then activate the source
source /Users/myusername/ENV/bin/activate
Install the apache-airflow:
pip install apache-airflow
then which airflow yields /Users/myusername/ENV/bin/airflow
But when I try to initdb using:
airflow initdb
I get below error:
{db.py:350} INFO - Creating tables
INFO [alembic.runtime.migration] Context impl SQLiteImpl.
INFO [alembic.runtime.migration] Will assume non-transactional DDL.
WARNI [airflow.utils.log.logging_mixin.LoggingMixin] cryptography not found - values will not be stored encrypted.
ERROR [airflow.models.DagBag] Failed to import: /Library/Python/2.7/site-packages/airflow/example_dags/example_http_operator.py
Traceback (most recent call last):
File "/Library/Python/2.7/site-packages/airflow/models/__init__.py", line 413, in process_file
m = imp.load_source(mod_name, filepath)
File "/Library/Python/2.7/site-packages/airflow/example_dags/example_http_operator.py", line 27, in <module>
from airflow.operators.http_operator import SimpleHttpOperator
File "/Library/Python/2.7/site-packages/airflow/operators/http_operator.py", line 21, in <module>
from airflow.hooks.http_hook import HttpHook
File "/Library/Python/2.7/site-packages/airflow/hooks/http_hook.py", line 23, in <module>
import tenacity
File "/Library/Python/2.7/site-packages/tenacity/__init__.py", line 375, in <module>
from tenacity.tornadoweb import TornadoRetrying
File "/Library/Python/2.7/site-packages/tenacity/tornadoweb.py", line 24, in <module>
from tornado import gen
File "/Library/Python/2.7/site-packages/tornado-6.0.3-py2.7-macosx-10.14-intel.egg/tornado/gen.py", line 126
def _value_from_stopiteration(e: Union[StopIteration, "Return"]) -> Any:
^
SyntaxError: invalid syntax
Done.
(ENV) ---------------------------------------------------------
Seems like example scripts use python 2.7 and it can't recognize the function definition syntax.
Does apache-airflow package need to be fixed by the next release or I can do something to fix this?
I tried fixing this:
Use python2.7 instead of python3
then install airflow on default python 2.7 enabled on mac but this throws other errors like package "six" is not compatible.

Answer 1

You need to turn off the example DAGs to be loaded in config file to solve this problem.
Anyway, it seems weird that airflow uses 2.7 Python when you told that it is installed into Python 3 virtual environment.