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"""
This is an example dag for using a Kubernetes Executor Configuration.
"""
from __future__ import print_function

import os

import airflow
from airflow.contrib.example_dags.libs.helper import print_stuff
from airflow.models import DAG
from airflow.operators.python_operator import PythonOperator


default_args = {
    'owner': 'Airflow',
    'start_date': airflow.utils.dates.days_ago(2)
}

with DAG(
    dag_id='example_kubernetes_executor_config',
    default_args=default_args,
    schedule_interval=None
) as dag:

    def test_volume_mount():
        """
        Tests whether the volume has been mounted.
        """
        with open('/foo/volume_mount_test.txt', 'w') as foo:
            foo.write('Hello')

        return_code = os.system("cat /foo/volume_mount_test.txt")
        assert return_code == 0

    # You can use annotations on your kubernetes pods!
    start_task = PythonOperator(
        task_id="start_task",
        python_callable=print_stuff,
        executor_config={
            "KubernetesExecutor": {
                "annotations": {"test": "annotation"}
            }
        }
    )

    # You can mount volume or secret to the worker pod
    second_task = PythonOperator(
        task_id="four_task",
        python_callable=test_volume_mount,
        executor_config={
            "KubernetesExecutor": {
                "volumes": [
                    {
                        "name": "example-kubernetes-test-volume",
                        "hostPath": {"path": "/tmp/"},
                    },
                ],
                "volume_mounts": [
                    {
                        "mountPath": "/foo/",
                        "name": "example-kubernetes-test-volume",
                    },
                ]
            }
        }
    )

    # Test that we can run tasks as a normal user
    third_task = PythonOperator(
        task_id="non_root_task",
        python_callable=print_stuff,
        executor_config={
            "KubernetesExecutor": {
                "securityContext": {
                    "runAsUser": 1000
                }
            }
        }
    )

    start_task >> second_task >> third_task
