create a new GET /api/activity endpoint for listing activity items.

src/metabase/api/activity.clj

+(ns metabase.api.activity
+  (:require [compojure.core :refer [GET POST]]
+            [korma.core :as k]
+            [metabase.api.common :refer :all]
+            [metabase.db :refer [exists? sel]]
+            (metabase.models [activity :refer [Activity]]
+                             [card :refer [Card]]
+                             [dashboard :refer [Dashboard]]
+                             [hydrate :refer [hydrate]])))
+
+(defendpoint GET "/"
+  "Get recent activity."
+  []
+  (-> (sel :many Activity (k/order :timestamp :DESC))
+      (hydrate :user)))
+
+(define-routes)

src/metabase/api/routes.clj

 (ns metabase.api.routes
   (:require [compojure.core :refer [context defroutes GET]]
             [compojure.route :as route]
-            (metabase.api [card :as card]
+            (metabase.api [activity :as activity]
+                          [card :as card]
                           [dash :as dash]
                           [notify :as notify]
                           [revision :as revision]
@@ -26,21 +27,22 @@
   auth/enforce-authentication)
 
 (defroutes routes
-  (context "/card"         [] (+auth card/routes))
-  (context "/dash"         [] (+auth dash/routes))
-  (GET     "/health"       [] {:status 200 :body {:status "ok"}})
+  (context "/activity" [] (+auth activity/routes))
+  (context "/card" [] (+auth card/routes))
+  (context "/dash" [] (+auth dash/routes))
+  (GET "/health" [] {:status 200 :body {:status "ok"}})
   (context "/meta/dataset" [] (+auth dataset/routes))
-  (context "/meta/db"      [] (+auth db/routes))
-  (context "/meta/field"   [] (+auth field/routes))
-  (context "/meta/fk"      [] (+auth fk/routes))
-  (context "/meta/table"   [] (+auth table/routes))
-  (context "/notify"       [] (+apikey notify/routes))
-  (context "/revision"     [] (+auth revision/routes))
-  (context "/session"      [] session/routes)
-  (context "/setting"      [] (+auth setting/routes))
-  (context "/setup"        [] setup/routes)
-  (context "/tiles"        [] (+auth tiles/routes))
-  (context "/user"         [] (+auth user/routes))
+  (context "/meta/db" [] (+auth db/routes))
+  (context "/meta/field" [] (+auth field/routes))
+  (context "/meta/fk" [] (+auth fk/routes))
+  (context "/meta/table" [] (+auth table/routes))
+  (context "/notify" [] (+apikey notify/routes))
+  (context "/revision" [] (+auth revision/routes))
+  (context "/session" [] session/routes)
+  (context "/setting" [] (+auth setting/routes))
+  (context "/setup" [] setup/routes)
+  (context "/tiles" [] (+auth tiles/routes))
+  (context "/user" [] (+auth user/routes))
   (route/not-found (fn [{:keys [request-method uri]}]
-                        {:status 404
-                         :body (str (.toUpperCase (name request-method)) " " uri " is not yet implemented.")})))
+                     {:status 404
+                      :body   (str (.toUpperCase (name request-method)) " " uri " is not yet implemented.")})))