handler.js

// config.js file must be like this
// module.exports = (offline) => {
//   return offline
//   ? {
//       awsAccountId: '123456789012',
//       region: 'us-east-1'
//   }
//   :{
//       awsAccountId: '098765432109', <- Real awsAccountId
//       region: 'us-east-1'
//   };
// }

const sendMessage = (event, context, callback) => {

    const AWS = require('aws-sdk');
    const config = require('./config')(process.env.IS_OFFLINE);

    const snsConfig = process.env.IS_OFFLINE
        ? {
            endpoint: 'http://127.0.0.1:4002',
            region: config.region,
        }
        : {};

    const message = { message: 'Ultra Test Message' };

    const snsPublishConfig = {
        Message: JSON.stringify({ default: JSON.stringify(message) }),
        MessageStructure: 'json',
        TopicArn: `arn:aws:sns:${config.region}:${config.awsAccountId}:sns-example-topic`,
    };

    const sns = new AWS.SNS(snsConfig);
    const snsPublish = sns.publish(snsPublishConfig).promise();

    snsPublish.then(
        () => {
            const response = {
                statusCode: 200,
                body: JSON.stringify({ message: 'message sent' })
            };
            callback(null, response);
        }
    ).catch(
        err => {
            console.error('ERROR: ', err);
        }
    );
};

const getMessage = (event, context, callback) => {
    console.info('incoming message: ', event.Records[0].Sns.Message);
    callback(null, { response: 'message received' });
};

module.exports = {
    sendMessage,
    getMessage
};