handler.js

'use strict'

/**
 * This is a sample Lambda function that sends an Email on click of a
 * button. It creates a SNS topic, subscribes an endpoint (EMAIL)
 * to the topic and publishes to the topic.
 *
 * Follow these steps to complete the configuration of your function:
 *
 * 1. Update the email environment variable with your email address.
 * 2. Enter a name for your execution role in the "Role name" field.
 *    Your function's execution role needs specific permissions for SNS operations
 *    to send an email. We have pre-selected the "AWS IoT Button permissions"
 *    policy template that will automatically add these permissions.
 */

const AWS = require('aws-sdk')
const SNS = new AWS.SNS({apiVersion: '2010-03-31'})

const dynamoDbHelper = require('./common/dynamodb-helper')
const snsHelper = require('./common/sns-helper')

const TABLE = process.env.DYNAMODB_TABLE_BUTTON

/**
 * The following JSON template shows what is sent as the payload:
 {
     "serialNumber": "GXXXXXXXXXXXXXXXXX",
     "batteryVoltage": "xxmV",
     "clickType": "SINGLE" | "DOUBLE" | "LONG"
 }
 *
 * A "LONG" clickType is sent if the first press lasts longer than 1.5 seconds.
 * "SINGLE" and "DOUBLE" clickType payloads are sent for short clicks.
 *
 * For more documentation, follow the link below.
 * http://docs.aws.amazon.com/iot/latest/developerguide/iot-lambda-rule.html
 */
exports.pubSNS = (event, context, callback) => {
  console.log('Received event:', event)

  // create/get topic
  snsHelper.createTopic('aws-iot-button-sns-topic', (err, topicArn) => {
    if (err) {
      return callback(err)
    }
    console.log(`Publishing to topic ${topicArn}`)
    // publish message
    const params = {
      Message: `${event.serialNumber} -- processed by Lambda\nBattery voltage: ${event.batteryVoltage}`,
      Subject: `Hello from your IoT Button ${event.serialNumber}: ${event.clickType}`,
      TopicArn: topicArn
    }

    console.log(JSON.stringify(params))

    const data = {
      serialNumber: event.serialNumber,
      batteryVoltage: event.batteryVoltage,
      clickType: event.clickType,
      timestamp: Date.now(),
      date: new Date().toJSON()
    }

    dynamoDbHelper.putItem(TABLE, data).then(() => SNS.publish(params, callback))
    .catch(error => callback(null, {statusCode: 400, body: JSON.stringify(error)}))
  })
}