Send failure email to recipients based on variable using Jinja - airflow

Question

I'm trying to send an email to certain people defined in a variable in the Airflow UI. I see a similar question here but mine is slightly different. I suspect I can't do this when I'm using Jinja templating?
Apache airflow sends sla miss emails only to first person on the list
My variable:
{ "config1" : "abc", "config2":500000, "email_on_failure_list": ["jorge#gmail.com","maria#gmail.com"]}
My dag. it's bad practice to use Variable.Get() in top level code when referencing a variable created in the Airflow UI. so I'm using Jinja templating but it doesn't seem to be working
email = "{{ var.json.my_dag.email_on_failure_list}}"
default_args = {
'depends_on_past': False,
'start_date': datetime(2020, 9, 1),
'email_on_failure': True,
'email': email
}
this is the error I receive
ERROR - Failed to send email to: {{ var.json.my_dag.email_on_failure_list}}
[2021-02-09 09:13:16,339] {{taskinstance.py:1201}} ERROR - {'{{ var.json.my_dag.email_on_failure_list}}': (501, b'5.1.3 Invalid address')}

Answer 1

Short answer: it's not possible with Jinja templates.
The alternative that was suggested on the Airflow Slack channel (Thanks Kaxil!) is to create an Environment Variable. I can then reference this using Variable.Get without any of the performance issues.
Environment variables aren't ideal for something non-sensitive since it requires more access to modify but it's a decent alternative to have different configuration settings across different Airflow environments (dev, qa, prod).
Follow the instructions here:
https://airflow.apache.org/docs/apache-airflow/2.0.1/howto/variable.html#storing-variables-in-environment-variables
Steps:
Create an environment variable on the airflow server (ex. AIRFLOW_VAR_MY_EMAIL_LIST). It's important to not create the variable in the Airflow UI
use it in your dag
from airflow.models import Variable
my_email_list = Variable.get("AIRFLOW_VAR_MY_EMAIL_LIST")
default_args = {
'depends_on_past': False,
'start_date': datetime(2020, 9, 1),
'email_on_failure': True,
'email': my_email_list
}