Slack Events API adapter for Crystal

The middlewares you need to deal with Slack Events API

Overview

slack-events-api is a Crystal package composed of two middlewares:

SlackEvents::VerificationHandler

• Middleware that verifies that requests are correctly signed with SLACK_SIGNING_SECRET by Slack. All requests going through this middleware, will be checked. In the event of a request whose signature couldn't be verified, the middleware will early return with a 403 - Forbidden.
• Receives SLACK_SIGNING_SECRET as its sole argument.

SlackEvents::ChallengeHandler

• Middleware that does the initial challenge handshake between Slack and your API.

Further documentation can be found in https://qu4tro.github.io/slack-events-api/

Installation

1. Add this to your application's shard.yml:

dependencies:
  slack-events-api:
    github: qu4tro/slack-events-api

2. Run shards install

Usage

This example will suffice to perform the initial setup, but actual events will be 404'd, until you write your application-specific handler.

#!/usr/bin/env crystal

require "http/server"
require "http/server/handler"

require "slack-events-api"

middlewares = [
  HTTP::LogHandler.new.as(HTTP::Handler),
  HTTP::ErrorHandler.new,
  SlackEvents::VerificationHandler.new(ENV["SLACK_SIGNING_SECRET"]),
  SlackEvents::ChallengeHandler.new,
] 

HTTP::Server.new(middlewares).tap do |server|
  address = server.bind_tcp "localhost", ENV["PORT"].to_i
  puts "Listening on http://#{address}"
  server.listen
end

Further work

• Make JSON mappings for all event types supported by the Event API
• If a reverse-proxy middleware comes up for Crystal, I think it's worth thinking about creating a docker image, to allow for the verification and challenge-setup to be automated for any ad-hoc server.

Development

Any restriction to development should be tool-automated. So, feel free to open PRs. If all the tests pass, it should be good to merge, if it fits the package domain - opening an issue is a good way to clarify. In fact, feel free to open issues for any type of clarification.

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Authors

• Xavier Francisco - Initial work - Qu4tro

License

This project is licensed under the MIT License - see the LICENSE.md file for details