Python 是否检索并将一个SSHOperator任务的结果传递给另一个任务？

我需要在SSHOperator中检索bash命令的输出（大小相当于文件大小）。我将使用此值作为条件检查，以扩展到其他任务。我正在使用xcom尝试检索该值，并使用branchpythonoperator来处理该决策，但我一直没有成功。SSHOperator似乎无法在xcom中获取值

以下是我的代码：

#Required packages to execute DAG

from __future__ import print_function
import logging
from airflow.models import DAG
from airflow.models import Variable
from datetime import datetime, timedelta
from airflow.contrib.operators.ssh_operator import SSHOperator
from airflow.operators.dummy_operator import DummyOperator
from airflow.operators.python_operator import BranchPythonOperator
from airflow.utils.trigger_rule import TriggerRule

log = logging.getLogger(__name__)

def decision_function(**context):
    ti = context['ti']
    fileSize = ti.xcom_pull(task_ids='get_param')
    log.info('File size is: {}'.format(fileSize))
    if fileSize >= 800000:
        return 'good_path'
    else:
        return 'bad_path'

# DAG parameters

default_args = {
    'owner': 'Me',
    'depends_on_past': False,
    'start_date': datetime(2020, 8, 17, 4, 15),
    'dagrun_timeout': None,
    'email': Variable.get('email'),
    'email_on_failure': False,
    'email_on_retry': False,
    'provide_context': True,
    'orientation': 'LR'#, TB, RL, BT)

}

# create DAG object with Name and default_args
with DAG(
    'a_param',
    schedule_interval=None,
    description='params',
    default_args=default_args
    ) as dag:

    # Define tasks
    begin = DummyOperator(
        task_id='begin',
        dag=dag
    )

    get_param = SSHOperator(
    ssh_conn_id="oci_connection",
    task_id='get_param',
    xcom_push=True,
    command="ls -ltr /tmp/adobegc.log | awk '{print $5}'",
    dag=dag)

    check_file = BranchPythonOperator(
    task_id='check_file',
    python_callable=decision_function,
    provide_context=True,
    dag=dag)

    good_path = DummyOperator(
        task_id='good_path',
        trigger_rule=TriggerRule.NONE_FAILED,
        dag=dag
    )

    bad_path = DummyOperator(
        task_id='bad_path',
        trigger_rule=TriggerRule.NONE_FAILED,
        dag=dag
    )

    begin >> get_param >> check_file
    check_file >> good_path
    check_file >> bad_path

check_fail任务失败，日志如下：

[2020-10-12 16:58:20,572] {base_task_runner.py:113} INFO - Job 111304: Subtask check_file /usr/local/lib/airflow/airflow/contrib/operators/ssh_operator.py:75: PendingDeprecationWarning: Invalid arguments were passed to SSHOperator (task_id: get_param). Support for passing such arguments will be dropped in Airflow 2.0. Invalid arguments were:
[2020-10-12 16:58:20,572] {base_task_runner.py:113} INFO - Job 111304: Subtask check_file *args: ()
[2020-10-12 16:58:20,572] {base_task_runner.py:113} INFO - Job 111304: Subtask check_file **kwargs: {'xcom_push': True}
[2020-10-12 16:58:20,573] {base_task_runner.py:113} INFO - Job 111304: Subtask check_file   super(SSHOperator, self).__init__(*args, **kwargs)
[2020-10-12 16:58:20,906] {base_task_runner.py:113} INFO - Job 111304: Subtask check_file Running <TaskInstance: a_param.check_file 2020-10-12T16:55:18.312240+00:00 [running]> on host airflow-worker-9b6fbd84c-l4jbs
[2020-10-12 16:58:20,990] {base_task_runner.py:113} INFO - Job 111304: Subtask check_file [2020-10-12 16:58:20,989] {a_param.py:25} INFO - File size is: None
[2020-10-12 16:58:20,990] {taskinstance.py:1135} ERROR - '>=' not supported between instances of 'NoneType' and 'int'
Traceback (most recent call last)
  File "/usr/local/lib/airflow/airflow/models/taskinstance.py", line 972, in _run_raw_tas
    result = task_copy.execute(context=context
  File "/usr/local/lib/airflow/airflow/operators/python_operator.py", line 141, in execut
    branch = super(BranchPythonOperator, self).execute(context
  File "/usr/local/lib/airflow/airflow/operators/python_operator.py", line 113, in execut
    return_value = self.execute_callable(
  File "/usr/local/lib/airflow/airflow/operators/python_operator.py", line 118, in execute_callabl
    return self.python_callable(*self.op_args, **self.op_kwargs
  File "/home/airflow/gcs/dags/a_param.py", line 26, in decision_functio
    if fileSize >= 800000
TypeError: '>=' not supported between instances of 'NoneType' and 'int

---

请查看，可能会有所帮助。@PhilippJohannis谢谢您的帮助，我将SSHhoperator中的

xcom\u push

参数更改为

do\u xcom\u push

。检查xcom页面，我没有得到预期的结果。我得到的是

key:return\u value；值：ODAwMAo=

。我希望文件大小在Value下。Value似乎是base64编码的，您可以测试它-它应该是

8000

@PhilippJohannis是的。为什么它返回base64编码？有没有办法使气流返回字符串值或int值？实际上，操作符是这样写的：

返回b64encode（agg_stdout）。decode（'utf-8'）

-我想你可以在再次读取值后再次解码它。

[2020-10-12 16:57:12,113] {base_task_runner.py:113} INFO - Job 111303: Subtask get_param [2020-10-12 16:57:12,112] {ssh_operator.py:109} INFO - Running command: ls -ltr /tmp/adobegc.log | awk '{print $5}'
[2020-10-12 16:57:12,549] {base_task_runner.py:113} INFO - Job 111303: Subtask get_param [2020-10-12 16:57:12,547] {ssh_operator.py:143} INFO - 516752