Create a serverless Slack App with AWS Lambda, API Gateway, DynamoDB, and CloudFormation. All services will be automatically provisioned for you. All that's needed is your Slack App keys.

1. Setup your AWS Credentials
2. Install Serverless.js

npm install -g serverless

3. Install The Serverless Slack App Template and provision all AWS services

serverless install --url https://github.com/johnagan/serverless-slack-app
cd serverless-slack-app
npm install
serverless deploy

1. Create a new Slack App
2. Use the generated POST url for Slack's slash commands, events, and interactive messages
3. Update the serverless.yml with your new Slack App keys

Slack	Serverless

1. Deploy the changes to AWS serverless deploy
2. Navigate to the GET url provided from serverless
3. Walk through the OAuth flow and install the App
4. Goto the team and test the slash command /greet

// Slash Command handler
slack.on('/greet', (msg, bot) => {
  let message = {
    text: "How would you like to greet the channel?",
    attachments: [{
      fallback: 'actions',
      callback_id: "greetings_click",
      actions: [
        { type: "button", name: "Wave", text: ":wave:", value: ":wave:" },
        { type: "button", name: "Hello", text: "Hello", value: "Hello" },
        { type: "button", name: "Howdy", text: "Howdy", value: "Howdy" },
        { type: "button", name: "Hiya", text: "Hiya", value: "Hiya" }
      ]
    }]
  };

  // ephemeral reply
  bot.replyPrivate(message); 
});


// Interactive Message handler
slack.on('greetings_click', (msg, bot) => {
  let message = { 
    // selected button value
    text: msg.actions[0].value 
  };  

  // public reply
  bot.reply(message);
});

1. Open the bot source code
2. Add/Remove/Update the code with your bot functionality
3. Run serverless deploy to deploy your changes to AWS
4. Rinse and repeat.

All the tokens and urls above were invalidated before posting this tutorial. You will need to use your own tokens