Using Slack

• Has been great
  • Over 150 members
  • Over 100 messages/week (up from 0/week)
• Miss the IRC bots
  • Karma
  • Silliness

Lets figure out how to get karma up and running

Build a Slack bot!

Few ways to implement this

• Use webhook events API
  • Main implementation
• Use RTM API
  • Uses web sockets - open connection
  • Very cool but not used at moment
• Use web API
  • Not ideal of retrieving messages
  • Useful for posting back

What is a webhook?

• Its a 'reverse API'
  • "Don't call us - we'll call you"
  • POST request to your service
• Required to have a way for Slack to reach you
  • Having your own web server
  • Using AWS API Gateway or the equivalent
    from Google, Azure, IBM, etc
  • Implement code to process the webhook

Implementing a receiver

• Build using your choice in language/framework
• Built mine using Lumen
  • Lightweight with plug-able features
    • Routes
    • Models/ORM
    • Config
    • Queues
  • API-only

Things to consider

• Webhook events from your vendor may be asynchronous
  • The data they are sending back is mostly useless :(
  • Use it to assume *an* event has occurred
    • See if they have an API call you can use to get 'at-moment' update of data.

Plan of action

• Get payload from Slack (POST request)
  • Validate request
• Queue it for processing
  • Do some basic check to put it in appropriate queue
• Return 200 response code
• Run a queue processing task every few seconds on server to process queue items

Why validate?

• Just make sure it is actually coming from Slack
  • Not a malicious person
  • Slack provides a token which you can use
  • Other services might not
    • IP whitelisting, other params in request

Why queue requests?

• If something goes wrong
  • Way to examine failed request
  • Have a way to possibly trigger other events
• Need to close out the https request as quickly as possible
  • Slack will continually try to resend messages that are not responded to.
  • Common in other vendors that also use webhook approach.

Anatomy of the app

config (for configuration)

.env file (unique to environment)

routes (for API routes - we just have one)

database (for schema/migrations/etc)

app (contains model, controller, helpers, etc)

tests (for your tests)

app directory (cont'd)

• Console
  • command line stuff
• Helpers
  • Helper classes, mock classes
• Http (most important)
  • Controller, middleware
• Jobs (second most important)
  • Queues
• Models
  • Content models (Karma, Slack users)

Lets look at code

https://gitlab.com/btmash/lumen-karmabot