Practical Pedestal/Swagger: Slack integration

slacky-server.herokuapp.com
oliyh/slacky

Created by Oliver Hine / @oliyh

Slack

A developer-friendly chat service

Memes!

"an idea, behavior, style, or usage that spreads from person to person within a culture"

The Slack "Slash" command

  POST

  token=gIkuvaNzQIHg97ATvDxqgjtO
  team_id=T0001
  team_domain=juxt
  channel_id=C2147483705
  channel_name=general
  user_id=U2147483697
  user_name=frankie
  command=/meme
  text=rich hickey | simple | made complex

pedestal-swagger

Deserialisation, coercion and related error handling

  (s/defschema SlackRequest
 {(req :token)        s/Str
  (req :team_id)      s/Str
  (req :team_domain)  s/Str
  (req :channel_id)   s/Str
  (req :channel_name) s/Str
  (req :user_id)      s/Str
  (req :user_name)    s/Str
  (req :command)      s/Str
  (req :text)         s/Str})

(swagger/defhandler slack-meme
 {:summary "Responds asynchonously to
            Slash commands from Slack"
  :parameters {:formData SlackRequest}
  :responses {200 {:schema MemeUrl}}}
 [{:keys [form-params] :as request}]

 (let [text (:text form-params)]
   {:status 200
    :body (meme/generate-meme text)))
              

frankiesardo/pedestal-swagger

Routing and interceptors

(swagger/defroutes api-routes
  {:info {:title "Slacky"
          :description "Memes and more for Slack"
          :externalDocs {:description "Find out more"
                         :url "https://github.com/oliyh/slacky"}
          :version "2.0"}
   :tags [{:name "meme"
           :description "All the memes!"}]}
  [[["/api" ^:interceptors [(swagger/body-params)
                            bootstrap/json-body
                            (swagger/coerce-request)
                            (swagger/validate-response)]

     ["/slack"
      ["/meme" ^:interceptors [(annotate {:tags ["meme"]})]
       {:post slack-meme}]]

     ["/swagger.json" {:get [(swagger/swagger-json)]}]
     ["/*resource" {:get [(swagger/swagger-ui)]}]]]])
          

Swagger UI

Responding to Slack

Authentication interceptor

(swagger/defbefore authenticate-slack-call
  {:description "Ensures caller has registered an incoming webhook"
   :parameters {:formData {:token s/Str}}
   :responses {403 {}}}
  [{:keys [request response] :as context}]

  (let [db (:db-connection request)
        token (get-in request [:form-params :token])
        account (accounts/lookup-slack-account db token)]
    (if-let [webhook-url (:key account)]
      (update context :request merge {::slack-webhook-url webhook-url
                                      ::account-id (:id account)})
      (-> (terminate context)
          (assoc :response
            {:status 403
             :headers {}
             :body (str "You are not permitted to use this service.\n"
                        "Please register your token '" token
                        "'at https://slacky-server.herokuapp.com")})))))
            

Self-migrating database

Ensure database is migrated before use

(defn- migrate-db [url]
    (joplin/migrate-db
     {:db {:type :jdbc :url url}
      :migrator "migrators/jdbc"}))

(defn create-db-connection [url]
  (migrate-db url)

  (condp re-find url
    #":postgresql:" (pool "org.postgresql.Driver" url))
    #":h2:" (pool "org.h2.Driver" url))

juxt/joplin

Extending to other services

(defroutes routes
  ["/api" ^:interceptors [rate-limiter]
    ["/slack" ^:interceptors [slack-auth] ...]
    ["/hipchat" ^:interceptors [hipchat-auth] ...]])

Angel interceptor

Decomplect interceptor scope from ordering

(require '[angel.interceptor :as angel])

(defroutes routes
  ["/api" ^:interceptors [(angel/requires rate-limiter :account)]
    ["/slack" ^:interceptors
              [(angel/provides slack-auth :account)] ...]
    ["/hipchat" ^:interceptors
                [(angel/provides hipchat-auth :account)] ...]])

(def service
  (angel/satisfy
    {:io.pedestal.http/routes routes}))

oliyh/angel-interceptor

Slacky

slacky-server.herokuapp.com

Epic memes

slacky-server.herokuapp.com

oliyh/slacky