cljs-lambda.util — io.nervous/cljs-lambda 0.3.6-SNAPSHOT

async-lambda-fn cljs

(async-lambda-fn f & [{:keys [error-handler] :as opts}])

Repurpose the two-arg (event, context) asynchronous function f as a Lambda handler. The function's result determines the invocation's success at the Lambda level, without the requirement of using Lambda-specific (context/fail!, etc.) functionality within the body. Optional error handler behaves as handle-errors.

If the handler was passed a callback by the Lambda harness, that function will be used to signal completion, over the the context methods.

Success:

• Returns successful Promesa/Bluebird promise
• Returns core.async channel containing non-js/Error
• Synchronously returns arbitrary object

(def ^:export wait
  (async-lambda-fn
   (fn [{n :msecs} ctx]
     (promesa/delay n :waited))))

Failure:

• Returns rejected Promesa/Bluebird promise
• Returns core.async channel containing js/Error
• Synchronously throws js/Error

(def ^:export blow-up
  (async-lambda-fn
   (fn [_ ctx]
     (go
       (<! (async/timeout 10))
       (js/Error. "I blew up")))))

See macros/deflambda for an alternative approach to defining/export handler vars.

handle-errors cljs

(handle-errors f error-handler)

Returns a Lambda handler delegating to the input handler f, conveying any errors to error-handler, a function of [error event ctx], which has the opportunity to modify the eventual handler response (rethrow, return promise/channel, etc.)

(def ^:export successful-fn
  (-> (fn [event ctx] (p/rejected (js/Error.)))
      (handle-errors (fn [e event ctx] "Success"))
      async-lambda-fn))

wrap-lambda-fn cljs

(wrap-lambda-fn f & [{parse-input? :parse-input? :or {parse-input? true}}])

Prepare a two-arg (event, context) function for exposure as a Lambda handler. The returned function will convert the event (Javascript Object) into a Clojurescript map with keyword keys, and turn the context into a record having keys :aws-request-id, :client-context, :log-group-name, :log-stream-name & :function-name - suitable for manipulation by context/done! etc.