text: # -*- coding: utf-8 -*-
  # Licensed to the Apache Software Foundation (ASF) under one
  # or more contributor license agreements.  See the NOTICE file
  # distributed with this work for additional information
  # regarding copyright ownership.  The ASF licenses this file
  # to you under the Apache License, Version 2.0 (the
  # "License"); you may not use this file except in compliance
  # with the License.  You may obtain a copy of the License at
  #
  #   http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing,
  # software distributed under the License is distributed on an
  # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  # KIND, either express or implied.  See the License for the
  # specific language governing permissions and limitations
  # under the License.
  
  """
  This sample "listen to directory". move the new file and print it,
  using docker-containers.
  The following operators are being used: DockerOperator,
  BashOperator & ShortCircuitOperator.
  TODO: Review the workflow, change it accordingly to
        your environment & enable the code.
  """
  
  # from __future__ import print_function
  #
  # from airflow import DAG
  # from datetime import timedelta
  # from airflow.operators import BashOperator
  # from airflow.operators import ShortCircuitOperator
  # from airflow.operators.docker_operator import DockerOperator
  # from airflow.utils.dates import days_ago
  #
  # default_args = {
  #     'owner': 'Airflow',
  #     'depends_on_past': False,
  #     'start_date': days_ago(2),
  #     'email': ['airflow@example.com'],
  #     'email_on_failure': False,
  #     'email_on_retry': False,
  #     'retries': 1,
  #     'retry_delay': timedelta(minutes=5),
  # }
  #
  # dag = DAG(
  #         'docker_sample_copy_data', default_args=
  #           default_args, schedule_interval=timedelta(minutes=10))
  #
  # locate_file_cmd = """
  #     sleep 10
  #     find {{params.source_location}} -type f  -printf "%f\n" | head -1
  # """
  #
  # t_view = BashOperator(
  #         task_id='view_file',
  #         bash_command=locate_file_cmd,
  #         xcom_push=True,
  #         params={'source_location': '/your/input_dir/path'},
  #         dag=dag)
  #
  #
  # def is_data_available(*args, **kwargs):
  #     ti = kwargs['ti']
  #     data = ti.xcom_pull(key=None, task_ids='view_file')
  #     return not data == ''
  #
  #
  # t_is_data_available = ShortCircuitOperator(
  #         task_id='check_if_data_available',
  #         provide_context=True,
  #         python_callable=is_data_available,
  #         dag=dag)
  #
  # t_move = DockerOperator(
  #         api_version='1.19',
  #         docker_url='tcp://localhost:2375',  # replace it with swarm/docker endpoint
  #         image='centos:latest',
  #         network_mode='bridge',
  #         volumes=['/your/host/input_dir/path:/your/input_dir/path',
  #                  '/your/host/output_dir/path:/your/output_dir/path'],
  #         command=[
  #             "/bin/bash",
  #             "-c",
  #             "/bin/sleep 30; "
  #             "/bin/mv {{params.source_location}}/{{ ti.xcom_pull('view_file') }} {{params.target_location}};"
  #             "/bin/echo '{{params.target_location}}/{{ ti.xcom_pull('view_file') }}';"
  #         ],
  #         task_id='move_data',
  #         xcom_push=True,
  #         params={'source_location': '/your/input_dir/path',
  #                 'target_location': '/your/output_dir/path'},
  #         dag=dag)
  #
  # print_templated_cmd = """
  #     cat {{ ti.xcom_pull('move_data') }}
  # """
  #
  # t_print = DockerOperator(
  #         api_version='1.19',
  #         docker_url='tcp://localhost:2375',
  #         image='centos:latest',
  #         volumes=['/your/host/output_dir/path:/your/output_dir/path'],
  #         command=print_templated_cmd,
  #         task_id='print',
  #         dag=dag)
  #
  # t_view.set_downstream(t_is_data_available)
  # t_is_data_available.set_downstream(t_move)
  # t_move.set_downstream(t_print)
  