🎉 Add basic error handling to exporter app.

exporter/src/app/http.cljs

@@ -4,7 +4,9 @@
    [lambdaisland.glogi :as log]
    [app.browser :as bwr]
    [app.http.screenshot :refer [bitmap-handler]]
+   [app.util.transit :as t]
    [reitit.core :as r]
+   [cuerdas.core :as str]
    ["koa" :as koa]
    ["http" :as http])
   (:import
@@ -29,6 +31,31 @@
                :params params
                :query-params qparams)))))
 
+(defn- handle-error
+  [error request]
+  (let [{:keys [type message code] :as data} (ex-data error)]
+    (cond
+      (= :validation type)
+      (let [header (get-in request [:headers "accept"])]
+        (if (and (str/starts-with? header "text/html")
+                 (= :spec-validation (:code data)))
+          {:status 400
+           :headers {"content-type" "text/html"}
+           :body (str "<pre style='font-size:16px'>" (:explain data) "</pre>\n")}
+          {:status 400
+           :headers {"x-metadata" (t/encode data)}
+           :body ""}))
+
+      :else
+      (do
+        (log/error :msg "Unexpected error"
+                   :error error)
+        {:status 500
+         :headers {"x-metadata" (t/encode {:type :unexpected
+                                           :message (ex-message error)})}
+         :body ""}))))
+
+
 (defn- handle-response
   [ctx {:keys [body headers status] :or {headers {} status 200}}]
   (run! (fn [[k v]] (.set ^js ctx k v)) headers)
@@ -36,15 +63,30 @@
   (set! (.-status ^js ctx) status)
   nil)
 
+(defn- parse-headers
+  [ctx]
+  (let [orig (unchecked-get ctx "headers")]
+    (persistent!
+     (reduce #(assoc! %1 %2 (unchecked-get orig %2))
+             (transient {})
+             (js/Object.keys orig)))))
+
 (defn- wrap-handler
   [f extra]
   (fn [ctx]
     (let [cookies (unchecked-get ctx "cookies")
-          request (assoc extra :ctx ctx :cookies cookies)]
+          headers (parse-headers ctx)
+          request (assoc extra
+                         :ctx ctx
+                         :headers headers
+                         :cookies cookies)]
       (-> (p/do! (f request))
-          (p/then (fn [rsp]
-                    (when (map? rsp)
-                      (handle-response ctx rsp))))))))
+          (p/then  (fn [rsp]
+                     (when (map? rsp)
+                       (handle-response ctx rsp))))
+          (p/catch (fn [err]
+                     (->> (handle-error err request)
+                          (handle-response ctx))))))))
 
 (def routes
   [["/export"

exporter/src/app/http/screenshot.cljs

@@ -2,7 +2,10 @@
   (:require
    [app.browser :as bwr]
    [app.config :as cfg]
-   [promesa.core :as p]))
+   [cljs.spec.alpha :as s]
+   [promesa.core :as p]
+   [uxbox.common.exceptions :as exc :include-macros true]
+   [uxbox.common.spec :as us]))
 
 (defn- load-and-screenshot
   [page url cookie]
@@ -27,13 +30,17 @@
               (load-and-screenshot page url cookie)))]
     (bwr/exec! browser on-browser)))
 
+(s/def ::page-id ::us/uuid)
+(s/def ::object-id ::us/uuid)
+(s/def ::bitmap-handler-params
+  (s/keys :req-un [::page-id ::object-id]))
+
 (defn bitmap-handler
   [{:keys [params browser cookies] :as request}]
-  (let [page-id   (get-in params [:query :page-id])
-        object-id (get-in params [:query :object-id])
-        token     (.get ^js cookies "auth-token")]
-    (-> (take-screenshot browser {:page-id page-id
-                                  :object-id object-id
+  (let [params (us/conform ::bitmap-handler-params (:query params))
+        token  (.get ^js cookies "auth-token")]
+    (-> (take-screenshot browser {:page-id (:page-id params)
+                                  :object-id (:object-id params)
                                   :token token})
         (p/then (fn [result]
                   {:status 200

exporter/src/app/util/transit.cljs

@@ -0,0 +1,32 @@
+;; This Source Code Form is subject to the terms of the Mozilla Public
+;; License, v. 2.0. If a copy of the MPL was not distributed with this
+;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+;;
+;; This Source Code Form is "Incompatible With Secondary Licenses", as
+;; defined by the Mozilla Public License, v. 2.0.
+;;
+;; Copyright (c) 2020 UXBOX Labs SL
+
+(ns app.util.transit
+  (:require
+   [cognitect.transit :as t]))
+
+;; --- Transit Handlers
+
+(def ^:private +read-handlers+
+  {"u" uuid})
+
+(def ^:private +write-handlers+
+  {})
+
+;; --- Public Api
+
+(defn decode
+  [data]
+  (let [r (t/reader :json {:handlers +read-handlers+})]
+    (t/read r data)))
+
+(defn encode
+  [data]
+  (let [w (t/writer :json {:handlers +write-handlers+})]
+    (t/write w data)))