outposts/proxy: make templates more re-usable

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

internal/outpost/proxyv2/application/error.go

@@ -2,33 +2,38 @@ package application
 
 import (
 	"fmt"
-	"html/template"
 	"net/http"
 
 	log "github.com/sirupsen/logrus"
 )
 
-// NewProxyErrorHandler creates a ProxyErrorHandler using the template given.
-func (a *Application) newProxyErrorHandler(errorTemplate *template.Template) func(http.ResponseWriter, *http.Request, error) {
-	return func(rw http.ResponseWriter, req *http.Request, proxyErr error) {
-		claims, _ := a.getClaims(req)
-		log.WithError(proxyErr).Warning("Error proxying to upstream server")
-		rw.WriteHeader(http.StatusBadGateway)
-		data := struct {
-			Title       string
-			Message     string
-			ProxyPrefix string
-		}{
-			Title:       "Bad Gateway",
-			Message:     "Error proxying to upstream server",
-			ProxyPrefix: "/akprox",
-		}
-		if claims != nil {
-			data.Message = fmt.Sprintf("Error proxying to upstream server: %s", proxyErr.Error())
-		}
-		err := errorTemplate.Execute(rw, data)
-		if err != nil {
-			http.Error(rw, "Internal Server Error", http.StatusInternalServerError)
-		}
+type ErrorPageData struct {
+	Title       string
+	Message     string
+	ProxyPrefix string
+}
+
+func (a *Application) ErrorPage(rw http.ResponseWriter, r *http.Request, err string) {
+	claims, _ := a.getClaims(r)
+	data := ErrorPageData{
+		Title:       "Bad Gateway",
+		Message:     "Error proxying to upstream server",
+		ProxyPrefix: "/akprox",
+	}
+	if claims != nil && len(err) > 0 {
+		data.Message = err
+	}
+	er := a.errorTemplates.Execute(rw, data)
+	if er != nil {
+		http.Error(rw, "Internal Server Error", http.StatusInternalServerError)
+	}
+}
+
+// NewProxyErrorHandler creates a ProxyErrorHandler using the template given.
+func (a *Application) newProxyErrorHandler() func(http.ResponseWriter, *http.Request, error) {
+	return func(rw http.ResponseWriter, req *http.Request, proxyErr error) {
+		log.WithError(proxyErr).Warning("Error proxying to upstream server")
+		rw.WriteHeader(http.StatusBadGateway)
+		a.ErrorPage(rw, req, fmt.Sprintf("Error proxying to upstream server: %s", proxyErr.Error()))
 	}
 }