airflow/sensors/bash.py

#
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# to you under the Apache License, Version 2.0 (the
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#   http://www.apache.org/licenses/LICENSE-2.0
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from __future__ import annotations

import os
from subprocess import PIPE, STDOUT, Popen
from tempfile import NamedTemporaryFile, TemporaryDirectory, gettempdir
from typing import TYPE_CHECKING, Sequence

from airflow.exceptions import AirflowFailException
from airflow.sensors.base import BaseSensorOperator

if TYPE_CHECKING:
    from airflow.utils.context import Context


class BashSensor(BaseSensorOperator):
    """
    Executes a bash command/script.

    Return 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.

    :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)
    :param output_encoding: output encoding of bash command.
    :param retry_exit_code: If task exits with this code, treat the sensor
        as not-yet-complete and retry the check later according to the
        usual retry/timeout settings. Any other non-zero return code will
        be treated as an error, and cause the sensor to fail. If set to
        ``None`` (the default), any non-zero exit code will cause a retry
        and the task will never raise an error except on time-out.

    .. seealso::
        For more information on how to use this sensor,take a look at the guide:
        :ref:`howto/operator:BashSensor`
    """

    template_fields: Sequence[str] = ("bash_command", "env")

    def __init__(
        self, *, bash_command, env=None, output_encoding="utf-8", retry_exit_code: int | None = None, **kwargs
    ):
        super().__init__(**kwargs)
        self.bash_command = bash_command
        self.env = env
        self.output_encoding = output_encoding
        self.retry_exit_code = retry_exit_code

    def poke(self, context: Context):
        """Execute the bash command in a temporary directory."""
        bash_command = self.bash_command
        self.log.info("Tmp dir root location: %s", gettempdir())
        with TemporaryDirectory(prefix="airflowtmp") as tmp_dir, 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)

            with Popen(
                ["bash", fname],
                stdout=PIPE,
                stderr=STDOUT,
                close_fds=True,
                cwd=tmp_dir,
                env=self.env,
                preexec_fn=os.setsid,
            ) as resp:
                if resp.stdout:
                    self.log.info("Output:")
                    for line in iter(resp.stdout.readline, b""):
                        self.log.info(line.decode(self.output_encoding).strip())
                resp.wait()
                self.log.info("Command exited with return code %s", resp.returncode)

                # zero code means success, the sensor can go green
                if resp.returncode == 0:
                    return True

                # we have a retry exit code, sensor retries if return code matches, otherwise error
                elif self.retry_exit_code is not None:
                    if resp.returncode == self.retry_exit_code:
                        self.log.info("Return code matches retry code, will retry later")
                        return False
                    else:
                        raise AirflowFailException(f"Command exited with return code {resp.returncode}")

                # backwards compatibility: sensor retries no matter the error code
                else:
                    self.log.info("Non-zero return code and no retry code set, will retry later")
                    return False