用创建IoT策略

Question

我正试图在中创建一个IoT策略。我当前的Lambda函数看起来是这样的：

​

"use strict";
const AWS = require("aws-sdk");
AWS.config.update({ region: "eu-central-1" });
var iot = new AWS.Iot();

exports.handler = async (event, context) => {


  var params = {
    policyDocument: `{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "iot:Connect"
      ],
      "Resource": [
        "arn:aws:iot:xxxxx:client/sander"
      ]
    },
    {
      "Effect": "Allow",
      "Action": [
        "iot:Subscribe"
      ],
      "Resource": [
        "arn:aws:iot:xxxx:topicfilter/$aws/things/ManuelBohrmaschine/shadow/*",
        "arn:aws:iot:xxxx:topicfilter/$aws/things/HeikoBohrmaschine/shadow/*"
      ]
    },
    {
      "Effect": "Allow",
      "Action": [
        "iot:Publish",
        "iot:Receive"
      ],
      "Resource": [
        "arn:aws:iot:xxxx:topic/$aws/things/ManuelBohrmaschine/shadow/*",
        "arn:aws:iot:xxxx:topic/$aws/things/HeikoBohrmaschine/shadow/*"
      ]
    }
  ]
}`,
    policyName: 'sander1231564654654654',
  };
  
  
  try{

    iot.createPolicy(params, function (err, data) {
      if (err) console.log(err, err); // an error occurred
      else {
        console.log("test")
        console.log(data);
        return {
          headers: {
            "Access-Control-Allow-Origin": "*", // Required for CORS support to work
            "Access-Control-Allow-Credentials": true // Required for cookies, authorization headers with HTTPS 
          },
          statusCode: 200,
          body: JSON.stringify(data)
        };

      }         
    });
  }
  catch(e){
    console.log(e);
  }
};

​

lambda函数只返回null，甚至不进入iot.createPolicy()的回调函数。我也试过了，没有试着去抓。同样的问题。没有正确的错误。我正在使用以下文档：https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/Iot.html#createPolicy-property

Answer 1

我认为原因是函数在有机会运行iot部分之前返回。这是异步处理程序的信标

如果您的代码执行异步任务，将返回一个承诺，以确保它完成运行。当您解决或拒绝承诺时，Lambda将向调用方发送响应或错误。

要克服这一问题，可以使用const promise = new Promise(...)，如文档中所示。

我修改了代码以使用Promise模式(见下文)。我不能保证它完全工作，但是您的函数现在应该能够执行iot.createPolicy部分了。

"use strict";
const AWS = require("aws-sdk");
AWS.config.update({ region: "eu-central-1" });
var iot = new AWS.Iot();

exports.handler = async (event, context) => {

  var params = {
    policyDocument: `{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "iot:Connect"
      ],
      "Resource": [
        "arn:aws:iot:xxxxx:client/sander"
      ]
    },
    {
      "Effect": "Allow",
      "Action": [
        "iot:Subscribe"
      ],
      "Resource": [
        "arn:aws:iot:xxxx:topicfilter/$aws/things/ManuelBohrmaschine/shadow/*",
        "arn:aws:iot:xxxx:topicfilter/$aws/things/HeikoBohrmaschine/shadow/*"
      ]
    },
    {
      "Effect": "Allow",
      "Action": [
        "iot:Publish",
        "iot:Receive"
      ],
      "Resource": [
        "arn:aws:iot:xxxx:topic/$aws/things/ManuelBohrmaschine/shadow/*",
        "arn:aws:iot:xxxx:topic/$aws/things/HeikoBohrmaschine/shadow/*"
      ]
    }
  ]
}`,
    policyName: 'sander1231564654654654',
  };

  const promise = new Promise(function(resolve, reject) {

  try{

    console.log(params);

    iot.createPolicy(params, function (err, data) {
      if (err) {
          console.log(err, err); // an error occurred
          reject(Error(err));
      }
      else {
        console.log("test")
        console.log(data);
        resolve({
          headers: {
            "Access-Control-Allow-Origin": "*", // Required for CORS support to work
            "Access-Control-Allow-Credentials": true // Required for cookies, authorization headers with HTTPS 
          },
          statusCode: 200,
          body: JSON.stringify(data)
        });

      }         
    });
  }
  catch(e){
    console.log(e);
  }
})
 return promise
};