[stream/ws_client] Reading long stdout is truncated at 32768 chars

[paramjeet01]

We are facing this issue in airflow and think it's due to python kubernetes-client. Earlier repo issue : https://github.com/kubernetes-client/python-base/issues/190 Airflow issue : https://github.com/apache/airflow/issues/39267 Error log :

[2024-04-26, 00:21:32 IST] {pod_manager.py:718} INFO - Checking if xcom sidecar container is started.
[2024-04-26, 00:21:32 IST] {pod_manager.py:721} INFO - The xcom sidecar container is started.
[2024-04-26, 00:21:32 IST] {pod_manager.py:798} INFO - Running command... if [ -s /airflow/xcom/return.json ]; then cat /airflow/xcom/return.json; else echo __airflow_xcom_result_empty__; fi
[2024-04-26, 00:21:36 IST] {pod_manager.py:798} INFO - Running command... if [ -s /airflow/xcom/return.json ]; then cat /airflow/xcom/return.json; else echo __airflow_xcom_result_empty__; fi
[2024-04-26, 00:21:40 IST] {pod_manager.py:798} INFO - Running command... if [ -s /airflow/xcom/return.json ]; then cat /airflow/xcom/return.json; else echo __airflow_xcom_result_empty__; fi
[2024-04-26, 00:21:44 IST] {pod_manager.py:798} INFO - Running command... if [ -s /airflow/xcom/return.json ]; then cat /airflow/xcom/return.json; else echo __airflow_xcom_result_empty__; fi
[2024-04-26, 00:21:52 IST] {pod_manager.py:798} INFO - Running command... if [ -s /airflow/xcom/return.json ]; then cat /airflow/xcom/return.json; else echo __airflow_xcom_result_empty__; fi
[2024-04-26, 00:21:52 IST] {pod_manager.py:798} INFO - Running command... kill -s SIGINT 1
[2024-04-26, 00:21:52 IST] {pod.py:909} INFO - Deleting pod: hps-mydata-generation-9lqygp1s
[2024-04-26, 00:21:52 IST] {taskinstance.py:2731} ERROR - Task failed with exception
Traceback (most recent call last):
  File "/opt/airflow/plugins/operators/kubernetes_pod_operator.py", line 200, in execute
    result = self.extract_xcom(pod=self.pod)
  File "/home/airflow/.local/lib/python3.10/site-packages/airflow/providers/cncf/kubernetes/operators/pod.py", line 557, in extract_xcom
    result = self.pod_manager.extract_xcom(pod)
  File "/home/airflow/.local/lib/python3.10/site-packages/airflow/providers/cncf/kubernetes/utils/pod_manager.py", line 730, in extract_xcom
    result = self.extract_xcom_json(pod)
  File "/home/airflow/.local/lib/python3.10/site-packages/tenacity/__init__.py", line 289, in wrapped_f
    return self(f, *args, **kw)
  File "/home/airflow/.local/lib/python3.10/site-packages/tenacity/__init__.py", line 379, in __call__
    do = self.iter(retry_state=retry_state)
  File "/home/airflow/.local/lib/python3.10/site-packages/tenacity/__init__.py", line 325, in iter
    raise retry_exc.reraise()
  File "/home/airflow/.local/lib/python3.10/site-packages/tenacity/__init__.py", line 158, in reraise
    raise self.last_attempt.result()
  File "/usr/local/lib/python3.10/concurrent/futures/_base.py", line 451, in result
    return self.__get_result()
  File "/usr/local/lib/python3.10/concurrent/futures/_base.py", line 403, in __get_result
    raise self._exception
  File "/home/airflow/.local/lib/python3.10/site-packages/tenacity/__init__.py", line 382, in __call__
    result = fn(*args, **kwargs)
  File "/home/airflow/.local/lib/python3.10/site-packages/airflow/providers/cncf/kubernetes/utils/pod_manager.py", line 765, in extract_xcom_json
    json.loads(result)
  File "/usr/local/lib/python3.10/json/__init__.py", line 346, in loads
    return _default_decoder.decode(s)
  File "/usr/local/lib/python3.10/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/local/lib/python3.10/json/decoder.py", line 355, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 16385 (char 16384)
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/home/airflow/.local/lib/python3.10/site-packages/airflow/models/taskinstance.py", line 439, in _execute_task
    result = _execute_callable(context=context, **execute_callable_kwargs)
  File "/home/airflow/.local/lib/python3.10/site-packages/airflow/models/taskinstance.py", line 414, in _execute_callable
    return execute_callable(context=context, **execute_callable_kwargs)
  File "/opt/airflow/plugins/operators/kubernetes_pod_operator.py", line 215, in execute
    self.cleanup(
  File "/home/airflow/.local/lib/python3.10/site-packages/airflow/providers/cncf/kubernetes/operators/pod.py", line 839, in cleanup
    raise AirflowException

[roycaihw]

/help

It is unclear where the limitation is coming from. Whether the limitation is coming from this client or some underlying library

[k8s-ci-robot]

@roycaihw: This request has been marked as needing help from a contributor.

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In response to [this](https://github.com/kubernetes-client/python/issues/2226): >/help > >It is unclear where the limitation is coming from. Whether the limitation is coming from this client or some underlying library Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes-sigs/prow](https://github.com/kubernetes-sigs/prow/issues/new?title=Prow%20issue:) repository.

[paramjeet01]

I'm not sure where the data is lost in between but I'm trying this code as suggested by @paul424 in this issue : https://github.com/kubernetes-client/python-base/issues/190. My understanding is that the data is lost while reading from the cat command,

def _extract_xcom(self, pod: V1Pod):
    try:
        self.log.info(f'Running command... cat {PodDefaults.XCOM_MOUNT_PATH}/return.json')

        # Can't use _preload_content=True because that would return str(json.load(response))
        client = kubernetes_stream(
            self._client.connect_get_namespaced_pod_exec,
            pod.metadata.name,
            pod.metadata.namespace,
            container=PodDefaults.SIDECAR_CONTAINER_NAME,
            command=[
                '/bin/sh',
                '-c',
                f'cat {PodDefaults.XCOM_MOUNT_PATH}/return.json',
            ],
            stderr=True,
            stdin=False,
            stdout=True,
            tty=False,
            _preload_content=False,
            _request_timeout=10,
        )
        client.run_forever(timeout=10)
        resp = client.read_all()
        self.log.info("Received {} ({}) ({} ... {}))".format(type(resp), len(resp), resp[:64], resp[-64:]))

        # validate it's valid json
        _ = json.loads(resp)

        # Terminate the sidecar
        _ = kubernetes_stream(
            self._client.connect_get_namespaced_pod_exec,
            pod.metadata.name,
            pod.metadata.namespace,
            container=PodDefaults.SIDECAR_CONTAINER_NAME,
            command=[
                '/bin/sh',
                '-c',
                'kill -s SIGINT 1',
            ],
            stderr=True,
            stdin=False,
            stdout=True,
            tty=False,
            _preload_content=True,
            _request_timeout=10,
        )

        return resp

    except JSONDecodeError:
        message = f'Failed to decode json document from pod: {pod.metadata.name}'
        self.log.exception(message)
        raise AirflowException(message)

    except Exception as e:
        message = f'Failed to extract xcom from pod: {pod.metadata.name}'
        self.log.exception(message)
        raise AirflowException(message)