在GKE POD中通过Cron执行时，无法使用Python SDK将消息发布到GCP发布/订阅 [英] Unable to publish messages to GCP Pub/Sub using Python SDK when executed via Cron inside a GKE POD

问题描述

使用PYthon SDK将消息发布到GCP发布/发布。代码正在GKE上的Kubernetes POD中运行。

Using a PYthon SDK to publish messages to GCP Pub/SUb. THe code is running inside a Kubernetes POD on GKE.

import pymysql
import os
import argparse
import time
from google.cloud import pubsub_v1

entries = ['jelly']

def publish_messages(project, topic_name):

  publisher = pubsub_v1.PublisherClient()
  topic_path = publisher.topic_path(project, topic_name)

  for n in entries:
    data = u'Message number {}'.format(n)
    data = data.encode('utf-8')
    publisher.publish(topic_path, data=data)
    print "Message %s sent to queue" % n

手动执行脚本可以正常工作。但是，通过Crontab触发时失败。

Script works fine when executed manually. However, it fails when triggered via Crontab.

Error: No handlers could be found for logger google.cloud.pubsub_v1.publisher._batch.thread"

推荐答案

找到了解决方案。
默认情况下，Crontab不会从系统环境变量中读取。上面的Python代码需要包含服务帐户密钥（在这种情况下为ConfigMap）的env变量 GOOGLE_APPLICATION_CREDENTIALS。为此，必须在运行时将所有的env变量打印到容器的 / etc / environment文件中
像这样：

Found the solution. Crontab by default doesn't read from the system environment variables. And this Python code above needs the env variable "GOOGLE_APPLICATION_CREDENTIALS" which holds the service Account key (ConfigMap in this case). To achieve this all the env variables must be printed out to "/etc/environment" file of the container on the runtime. Something like this:

FROM ubuntu:latest
ADD send.py Jelly/send.py
COPY jellycron /etc/cron.d/jellycron
RUN apt-get update && apt-get install -y cron vim mysql-server curl python python-pip 
    && pip install --upgrade pymysql google-api-python-client google-cloud google- 
    cloud-pubsub && touch /var/log/cron.log && chmod 0644 /etc/cron.d/jellycron && 
    crontab /etc/cron.d/jellycron
CMD printenv >> /etc/environment && cron && tail -f /var/log/cron.log

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