gm55 opened a new issue #14287:
URL: https://github.com/apache/airflow/issues/14287
**Environment:**
Airflow 2.0.1, Python 3.7.9. KubernetesExecutor is set in the configuration.
**Issue:**
KubernetsPodOperators does not process env_vars with Jinja templates like {{
dag.conf['key'] }} and leaves text as is, no substitution is done.
The method
[render_template](https://github.com/apache/airflow/blob/2.0.1/airflow/models/baseoperator.py#L875)
of BaseOperator checks types of content using
```Python
if isinstance(content, <some_type>):
```
As **env_vars** of type List[V1EnvVar] is submitted to render_templates as
a content parameter and has type 'list', it is passed to that part:
```Python
elif isinstance(content, list):
return [self.render_template(element, context, jinja_env) for element
in content]
```
But elements now have type <class
'kubernetes.client.models.v1_env_var.V1EnvVar'>, not a 'dict'
Old version would have processed the template in the following part:
```Python
elif isinstance(content, dict):
return {key: self.render_template(value, context, jinja_env) for key,
value in content.items()}
```
But now it goes to the very end of the method, into the final 'else'. The
type <class 'kubernetes.client.models.v1_env_var.V1EnvVar'> is not mentioned
anywhere above and this part is the last resort for it.
```Python
else:
if seen_oids is None:
seen_oids = set()
self._render_nested_template_fields(content, context, jinja_env,
seen_oids)
```
This part does nothing as env_vars elements are not nested templates.
[KubernetesPodOperator](https://github.com/apache/airflow/blob/2.0.1/airflow/providers/cncf/kubernetes/operators/kubernetes_pod.py#L158)
has the following list of fields that support substitution by Jinja. So
expansion of templates in env_vars should be supported.
```Python
template_fields: Iterable[str] = (
'image',
'cmds',
'arguments',
'env_vars',
'labels',
'config_file',
'pod_template_file',
```
It happens when a dag triggers another dag and sets env_vars.
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