From 79f2528419015a21df7d6e917a061fcf707dfd09 Mon Sep 17 00:00:00 2001
From: Victor Vrantchan <groob@users.noreply.github.com>
Date: Fri, 3 Mar 2017 19:49:55 -0500
Subject: [PATCH] provide context for ServeFrontend 500 errors (#1349)

Closes #1343
---
 cli/serve.go               |  2 +-
 server/service/frontend.go | 16 +++++++++++-----
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/cli/serve.go b/cli/serve.go
index 53309e5443..f2a5ce6e65 100644
--- a/cli/serve.go
+++ b/cli/serve.go
@@ -122,7 +122,7 @@ the way that the kolide server works.
 
 			var apiHandler, frontendHandler http.Handler
 			{
-				frontendHandler = prometheus.InstrumentHandler("get_frontend", service.ServeFrontend())
+				frontendHandler = prometheus.InstrumentHandler("get_frontend", service.ServeFrontend(httpLogger))
 				apiHandler = service.MakeHandler(ctx, svc, config.Auth.JwtKey, httpLogger)
 
 				setupRequired, err := service.RequireSetup(svc)
diff --git a/server/service/frontend.go b/server/service/frontend.go
index d5239c2b7d..f9f3e00ee6 100644
--- a/server/service/frontend.go
+++ b/server/service/frontend.go
@@ -6,6 +6,7 @@ import (
 	"net/http"
 
 	assetfs "github.com/elazarl/go-bindata-assetfs"
+	"github.com/go-kit/kit/log"
 )
 
 func newBinaryFileSystem(root string) *assetfs.AssetFS {
@@ -17,26 +18,31 @@ func newBinaryFileSystem(root string) *assetfs.AssetFS {
 	}
 }
 
-func ServeFrontend() http.Handler {
+func ServeFrontend(logger log.Logger) http.Handler {
+	herr := func(w http.ResponseWriter, err string) {
+		logger.Log("err", err)
+		http.Error(w, err, http.StatusInternalServerError)
+		return
+	}
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		fs := newBinaryFileSystem("/frontend")
 		file, err := fs.Open("templates/react.tmpl")
 		if err != nil {
-			http.Error(w, err.Error(), http.StatusInternalServerError)
+			herr(w, "load react template: "+err.Error())
 			return
 		}
 		data, err := ioutil.ReadAll(file)
 		if err != nil {
-			http.Error(w, err.Error(), http.StatusInternalServerError)
+			herr(w, "read bindata file: "+err.Error())
 			return
 		}
 		t, err := template.New("react").Parse(string(data))
 		if err != nil {
-			http.Error(w, err.Error(), http.StatusInternalServerError)
+			herr(w, "create react template: "+err.Error())
 			return
 		}
 		if err := t.Execute(w, nil); err != nil {
-			http.Error(w, err.Error(), http.StatusInternalServerError)
+			herr(w, "execute react template: "+err.Error())
 			return
 		}
 	})