Support creating a lambda directly from a ring handler

README.md

@@ -49,7 +49,19 @@ Add `ring/ring-core`, `ring/ring-json`,`compojure`,`lambdada` and `cheshire` dep
   (with-open [writer (io/writer os)]
     (let [request (parse-stream (io/reader is :encoding "UTF-8") true)]
       (generate-stream (handler request) writer))))
+```
+
+Alteratively, you can use the ring-handler->lambda utility function
 
+```clojure
+;; no wrap-apigw
+(def handler (wrap-json-response
+               (wrap-json-params
+                 (wrap-params
+                   (wrap-keyword-params
+                     app)))))
+
+(deflambda-ring-handler example.LambdaRingHandler handler)
 ```
 
 It is a common to use AWS Scheduled Events to warmup the Lambda function.

src/ring/middleware/apigw.clj

@@ -1,47 +1,9 @@
 (ns ring.middleware.apigw
-  (:require [clojure.string :as string])
-  (:import [java.io ByteArrayInputStream]
-           [java.net URLEncoder]))
-
-(defn- generate-query-string [params]
-  (string/join "&" (map (fn [[k v]]
-                          (str (URLEncoder/encode (name k)) "=" (URLEncoder/encode v)))
-                        params)))
-
-(defn- request->http-method [request]
-  (-> (:httpMethod request)
-      (string/lower-case)
-      (keyword)))
-
-(defn- apigw-request->ring-request [apigw-request]
-  {:pre [(every? #(contains? apigw-request %) [:httpMethod :path :queryStringParameters])
-         (contains? #{"GET" "POST" "OPTIONS" "DELETE" "PUT"} (:httpMethod apigw-request))]}
-  {:uri (:path apigw-request)
-   :query-string (generate-query-string (:queryStringParameters apigw-request))
-   :request-method (request->http-method apigw-request)
-   :headers (:headers apigw-request)
-   :body (when-let [body (:body apigw-request)] (ByteArrayInputStream. (.getBytes body "UTF-8")))})
-
-(defn- no-scheduled-route-configured-error [request]
-  (throw (ex-info "Got Scheduled Event but no scheduled-event-route configured"
-                  {:request request})))
-
-(defn- apigw->ring-request [request scheduled-event-route]
-  (let [scheduled-event? (= "Scheduled Event" (:detail-type request))]
-    (cond
-      (and scheduled-event? scheduled-event-route) (apigw-request->ring-request {:path scheduled-event-route
-                                                                                 :queryStringParameters ""
-                                                                                 :headers nil
-                                                                                 :httpMethod "GET"})
-      scheduled-event? (no-scheduled-route-configured-error request)
-      :else (apigw-request->ring-request request))))
+  (:require [ring-apigw-lambda-proxy.core :refer [apigw->ring-request ring-response->apigw]]))
 
 (defn wrap-apigw-lambda-proxy
   ([handler] (wrap-apigw-lambda-proxy handler {}))
   ([handler {:keys [scheduled-event-route]}]
    (fn [request]
      (let [response (handler (apigw->ring-request request scheduled-event-route))]
-       {:statusCode (:status response)
-        :headers (:headers response)
-        :body (:body response)}))))
-
+       (ring-response->apigw response)))))

src/ring_apigw_lambda_proxy/core.clj

@@ -0,0 +1,49 @@
+(ns ring-apigw-lambda-proxy.core
+  (:require [clojure.string :as string])
+  (:import [java.io ByteArrayInputStream]
+           [java.net URLEncoder]))
+
+(defn- generate-query-string [params]
+  (string/join "&" (map (fn [[k v]]
+                          (str (URLEncoder/encode (name k)) "=" (URLEncoder/encode v)))
+                        params)))
+
+(defn- request->http-method [request]
+  (-> (:httpMethod request)
+      (string/lower-case)
+      (keyword)))
+
+(defn- apigw-request->ring-request [apigw-request]
+  {:pre [(every? #(contains? apigw-request %) [:httpMethod :path :queryStringParameters])
+         (contains? #{"GET" "POST" "OPTIONS" "DELETE" "PUT"} (:httpMethod apigw-request))]}
+  {:uri (:path apigw-request)
+   :query-string (generate-query-string (:queryStringParameters apigw-request))
+   :request-method (request->http-method apigw-request)
+   :headers (:headers apigw-request)
+   :body (when-let [body (:body apigw-request)] (ByteArrayInputStream. (.getBytes body "UTF-8")))})
+
+(defn- no-scheduled-route-configured-error [request]
+  (throw (ex-info "Got Scheduled Event but no scheduled-event-route configured"
+                  {:request request})))
+
+(defn apigw->ring-request [request scheduled-event-route]
+  (let [scheduled-event? (= "Scheduled Event" (:detail-type request))]
+    (cond
+      (and scheduled-event? scheduled-event-route) (apigw-request->ring-request {:path scheduled-event-route
+                                                                                 :queryStringParameters ""
+                                                                                 :headers nil
+                                                                                 :httpMethod "GET"})
+      scheduled-event? (no-scheduled-route-configured-error request)
+      :else (apigw-request->ring-request request))))
+
+(defn ring-response->apigw [response]
+  {:statusCode (:status response)
+   :headers (:headers response)
+   :body (:body response)})
+
+(defmacro deflambda-ring-handler [name handler & [scheduled-event-route]]
+  `(uswitch.lambada.core/deflambdafn ~name [is# os# ctx#]
+     (with-open [writer# (clojure.java.io/writer os#)]
+       (let [request# (cheshire.core/parse-stream (io/reader is# :encoding "UTF-8") keyword)
+             response# (-> request# (apigw->ring-request ~scheduled-event-route) ~handler ring-response->apigw)]
+         (cheshire.core/generate-stream response# writer#)))))