airflow/sensors/bash.py

# -*- 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,
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# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
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import os
from subprocess import PIPE, STDOUT, Popen
from tempfile import NamedTemporaryFile, TemporaryDirectory, gettempdir

from airflow.sensors.base_sensor_operator import BaseSensorOperator
from airflow.utils.decorators import apply_defaults


class BashSensor(BaseSensorOperator):
    """
    Executes a bash command/script and returns True if and only if the
    return code is 0.

    :param bash_command: The command, set of commands or reference to a
        bash script (must be '.sh') to be executed.
    :type bash_command: str

    :param env: If env is not None, it must be a mapping that defines the
        environment variables for the new process; these are used instead
        of inheriting the current process environment, which is the default
        behavior. (templated)
    :type env: dict
    :param output_encoding: output encoding of bash command.
    :type output_encoding: str
    """

    template_fields = ('bash_command', 'env')

    @apply_defaults
    def __init__(self,
                 bash_command,
                 env=None,
                 output_encoding='utf-8',
                 *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.bash_command = bash_command
        self.env = env
        self.output_encoding = output_encoding

    def poke(self, context):
        """
        Execute the bash command in a temporary directory
        which will be cleaned afterwards
        """
        bash_command = self.bash_command
        self.log.info("Tmp dir root location: \n %s", gettempdir())
        with TemporaryDirectory(prefix='airflowtmp') as tmp_dir:
            with NamedTemporaryFile(dir=tmp_dir, prefix=self.task_id) as f:
                f.write(bytes(bash_command, 'utf_8'))
                f.flush()
                fname = f.name
                script_location = tmp_dir + "/" + fname
                self.log.info("Temporary script location: %s", script_location)
                self.log.info("Running command: %s", bash_command)
                sp = Popen(
                    ['bash', fname],
                    stdout=PIPE, stderr=STDOUT,
                    close_fds=True, cwd=tmp_dir,
                    env=self.env, preexec_fn=os.setsid)

                self.sp = sp

                self.log.info("Output:")
                for line in iter(sp.stdout.readline, b''):
                    line = line.decode(self.output_encoding).strip()
                    self.log.info(line)
                sp.wait()
                self.log.info("Command exited with return code %s", sp.returncode)

                return not sp.returncode