Node.js 如何从 Mongo Atlas 触发器向 GCP PubSub 发出经过身份验证的请求

我有以下代码:

exports = function(changeEvent) {
  var {PubSub} = require("@google-cloud/pubsub");
  var avro = require("avro-js");
  const keyFilename = context.values.get("GOOGLE_APPLICATION_CREDENTIALS")
  const projectId = "<project_name>"
  const pubSubClient = new PubSub({projectId, keyFilename});
  const topicName = "<topic_name>"
  const topic = pubSubClient.topic(topicName);
  try {
    const data = "something";
    const dataBuffer = Buffer.from(data);
    return topic.publish(dataBuffer)
      .then((messageId) => console.log(`Message ${messageId} published.`))
      .catch((err) => console.log(`Error publishing message: ${err}`));
  } catch(err) {
    console.log("Error: ", err.message);
  }
};

运行上述命令时，它返回以下内容:

Error publishing message: FunctionError: TypeError: 'createReadStream' is not a function
> result: 
{
   "$undefined": true
}
> result (JavaScript): 
EJSON.parse('{"$undefined":true}')

需要指出的是:

1. 我不是第一个遇到这个问题的人，但这两个帖子都没有得到太多关注
   • https://www.mongodb.com/community/forums/t/how-do-i-send-the-event-changes-of-a-collection-to-pub-sub/225384个
   • https://www.mongodb.com/community/forums/t/publishing-to-google-pubsub/201024个
2. The GOOGLE_APPLICATION_CREDENTIALS value ought to be a path to the secret called service-account.. it's a json of a service account key from GCP. What confuses me though is that if I console.log the path it prints out the secret as json and not the path to the secret

在这一点上，我不确定它能是什么.起初，我认为这可能是异步和同步的问题.但我try 了这两种方法，结果都出现了相同的错误.另一个问题可能是与客户端的身份验证.但是错误消息并没有为我提供太多信息，在搜索createReadStream的时候，我找不到任何有用的东西.