Airflow won't let me convert try_number macros to an integer - airflow-scheduler

Question

My issue is rather simple, but yet no real solution is really offered. The DAG I am trying to build will have a critical environment variable that might change depending on the number of retries that it goes through. For example, after 3 retries we will switch the value of the environment variable "critical_value" value mentioned in the code below.
So when I push the code below, I get the following broken DAG error:
Broken DAG: [/usr/local/airflow/dags/sync/dags/example_dag.py] invalid literal for int() with base 10: '{{ task_instance.try_number }}'
This is an error we get when we try to convert a string to an int. In this case, at runtime '{{ task_instance.try_number }}' will take the appropriate value of the try number of the run. I have tried also removing the int() converter but then get an error of comparing an integer and a string.
Any help will be immensely appreciated! Thank you in advance.
# Required DAG arguments
default_args = {
'owner':airflow,
"depend_on_past":False,
'start_date':datetime(2021, 6, 4),
"retries": 3
}
# Instantiate DAG
with DAG(
example_dag,
default_args=default_args,
schedule_interval=#once,
) as dag:
# Run python script of loader job
full_script_task = KubernetesPodOperator(
name=example_task,
task_id=example_task_id,
namespace=Variable.get("kubernetes_namespace"),
image=some_image,
configmaps=CONFIG_MAPS,
secrets=SECRETS,
volumes=[logging_volume],
volume_mounts=[logging_volume_mount],
env_vars={
"critical_value": "value_if_true" if int('{{ task_instance.try_number }}') >= 3 else "value_if_false"
}
)

Answer 1

Aiflow can handle the if expression and correct typing evaluation in Jinja but the whole value needs to be in the template syntax. Try this (env_vars needs to be a list based on the documentation of the KubernetesPodOperator otherwise the value will be a stringified list):
env_vars=[
{
"critical_value": "{{ 'value_if_true' if task_instance.try_number >= 3 else 'value_if_false' }}"
}
],

Answer 2

As we confirmed with your test, you cannot use jinja templated variables in an if clause inside the parameter. You tried this and the variable was read properly:
env_vars={
"critical_value": "{{ task_instance.try_number }}"
}
What you can do is to process the try_number inside the operator and instead of acting upon the critical_value, just use the try_number.