How to publish to iot stream from lambda - aws-lambda

Question

I keep having a timeout in my lambda function when I try to call the iotData publish function. Code below. It always times out without error. This function works from the sam local command line. I imagine this is a permissions error with lambda. The strange thing is I've given permissions for IoT, Kinesis and SNS already to this lambda function but nothing is working.
'use strict';
console.log('Loading function');
require('dotenv').config();
const {Pool} = require('pg');
const pool = new Pool();
const AWS = require('aws-sdk');
console.log("finished loading");
/** * Provide an event that contains the following keys:
* * * - resource: API Gateway resource for event
* * - path: path of the HTTPS request to the microservices API call
* * - httpMethod: HTTP method of the HTTPS request from microservices API call
* * - headers: HTTP headers for the HTTPS request from microservices API call
* * - queryStringParameters: query parameters of the HTTPS request from microservices API call
* * - pathParameters: path parameters of the HTTPS request from microservices API call
* * - stageVariables: API Gateway stage variables, if applicable
* * - body: body of the HTTPS request from the microservices API call
* */
exports.handler = function(event, context, callback) {
console.log("starting");
let _response = "";
context.callbackWaitsForEmptyEventLoop = false;
if(event.httpMethod==="POST" && event.resource==="/pings"){
var body = JSON.parse(event.body);
console.log("here2");
pool.query("SELECT name from pings where test = decode($1,'hex');",[body.bid], (err,res)=>{
if(err){
console.error(err.stack);
_response = buildOutput(500, {
message:"error in pg"
});
callback(_response, null);
}
console.log("here3");
var iotdata = new AWS.IotData({endpoint:'XXXXXXX.iot.us-east-1.amazonaws.com'});
const publishParams = {
topic: body.topic,
payload: Buffer.from(JSON.stringify({
message: "Welcome to "+res.rows[0].name+" house"
}), 'utf8'),
qos: 0
}
console.log("here4");
iotdata.publish(publishParams, function(err, data) {
if(err){
console.error(err.stack);
_response = buildOutput(500, {
message:"error in pg"
});
callback(_response,null);
}
_response = buildOutput(200, {message: "success"});
callback(null, _response);
});
});
} else {
_response = buildOutput(500, {
message:"path not found"
});
callback(_response,null);
}
};
/* Utility function to build HTTP response for the microservices output */
function buildOutput(statusCode, data) {
let _response = {
statusCode: statusCode,
headers: {
"Access-Control-Allow-Origin": "*"
},
body: JSON.stringify(data)
};
return _response;
}
policy
{
"Sid": "",
"Effect": "Allow",
"Action": [
"iot:*"
],
"Resource": "*"
},
UPDATE:
I attempted to give the lambda function admin access temporarily and that did not even work.

Answer 1

This is how you can post on MQTT topic directly from lambda function.
Use the code written in Node.js 10.x
var AWS = require('aws-sdk');
const IOT_ENDPOINT = "yourIoTentPoint.iot.region.amazonaws.com"
var iotdata = new AWS.IotData({endpoint:IOT_ENDPOINT});
exports.handler = function(event, context, callback) {
var params = {
topic: 'my/topic',
payload: 'This is my menssage from Lambda function.',
qos: 1
};
iotdata.publish(params, function(err, data){
if(err){
callback(err, null);
}
else{
callback(null, {"published_message": params.payload, "topic": params.topic});
}
});
};
Also, you can check the message sent by subscribing on the topic my/topic through IoT Core>Test on AWS Console.