如何解决：Node.js 服务器中的 onclosenexttick 过早关闭？

Question

如何解决这个错误，我运行我的 Node.js 使用 AWS IoT 然后它有时会显示这个错误：

      throw er; // Unhandled 'error' event
      ^

Error: How  (/home/ec2-user/work/nodejs_27_01/node_modules/end-of-stream/index.js:54:                                                                                                     86)
    at processTicksAndRejections (internal/process/task_queues.js:79:11)
Emitted 'error' event on DeviceClient instance at:
    at MqttClient.<anonymous> (/home/ec2-user/work/nodejs_27_01/node_modules/aws-iot-device-sdk/                                                                                                     device/index.js:772:15)
    at MqttClient.emit (events.js:333:22)
    at MqttClient.EventEmitter.emit (domain.js:485:12)
    at TLSSocket.f (/home/ec2-user/work/nodejs_27_01/node_modules/once/once.js:25:25)
    at onclosenexttick (/home/ec2-user/work/nodejs_27_01/node_modules/end-of-stream/index.js:54:                                                                                                     73)

Answer 1

这可能有多种原因：

具有相同 ClientId 的多个连接

clientId 一次只能用于一个连接。如果您在建立另一个连接时使用相同的 clientId 连接，旧连接将被丢弃（这会导致过早关闭错误）并建立新连接。

The client is using a client ID that is already in use. In this case, the client that is already connected will be disconnected [...]. (Source)

权限

如果设备（来自 aws-iot-device-sdk-js 的 mqtt.Client）没有正确的权限来连接给定主题的 and/or publish/subscribe/receive 消息，就会发生此错误。

查看此处了解更多文档：https://docs.aws.amazon.com/iot/latest/developerguide/pub-sub-policy.html

策略应如下所示（示例显示 Cloudformation Iot Policy 资源）：

MyIotThingsPolicy:
  Type: AWS::IoT::Policy
  Properties:
    PolicyDocument:
      Version: "2012-10-17"
      Statement:
        - Action: iot:Connect
          Effect: Allow
          Resource: !Join [ "", [!Sub "arn:aws:iot:${AWS::Region}:${AWS::AccountId}:client/",
                                 "${iot:ClientId}"] ]
        - Action: iot:Receive
          Effect: Allow
          Resource: !Join [ "", [!Sub "arn:aws:iot:${AWS::Region}:${AWS::AccountId}:topic/",
                                "${iot:ClientId}/eg/your/broadcast/topic"] ]
        - Action: iot:Subscribe
          Effect: Allow
          Resource: !Join [ "", [!Sub "arn:aws:iot:${AWS::Region}:${AWS::AccountId}:topicfilter/",
                                 "${iot:ClientId}/eg/your/broadcast/topic"] ]
        - Action: iot:Publish
          Effect: Allow
          Resource: !Join [ "", [!Sub "arn:aws:iot:${AWS::Region}:${AWS::AccountId}:topic/",
                                 "${iot:ClientId}/eg/your/publish/topic"] ]

!Join 是必需的，因为 Cloudformation 会尝试解析 ${iot:ClientId}，这是一个运行时值，在部署期间未知。

疑难解答

正如Sandeep Patel也建议的那样，如果你想在客户端处理这种情况，你应该实现一个错误回调：
```
device.on('error', (error) => {
  // error.message might be 'premature close'
});
```
您还可以在主题 $aws/events/presence/disconnected/<clientId> 上查找 disconnectReason，请参阅：https://docs.aws.amazon.com/iot/latest/developerguide/life-cycle-events.html

Answer 2

我可以不受任何限制地使用该策略解决这个问题，它适用于 me.Since 我不想限制连接的客户端以及订阅或发布的主题我使用了这个策略

"Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": "iot:*",
      "Resource": "*"
    }
  ]

Answer 3

在测试时，我附加了具有完整 "Action": "iot:*" 权限的策略，但未能激活新创建的证书。请转到 IoT 核心服务，Secure --> Certificates 并确认附加到 <Thing> 的证书已激活，如果您确认连接到 error Error: premature close终点为：

telnet <your-iot-endpoint> 8883.

请参阅附件图片，了解上述指定页面上每个证书可用的选项。

如何解决：Node.js 服务器中的 onclosenexttick 过早关闭？

How to solve: premature close at onclosenexttick in Node.js Server?

node.js

amazon-web-services

aws-iot

具有相同 ClientId 的多个连接

权限

疑难解答