Added: example of external service response headers propagation (requested by @aledbf)

examples/customization/external-auth-headers/nginx/authsvc/Dockerfile

@@ -0,0 +1,5 @@
+FROM alpine:3.5
+MAINTAINER Roman Safronov <electroma@gmail.com>
+COPY authsvc /
+EXPOSE 8080
+ENTRYPOINT ["/authsvc"]

examples/customization/external-auth-headers/nginx/authsvc/authsvc.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+	"math/rand"
+	"strconv"
+)
+
+// Sample authentication service returning several HTTP headers in response
+func main() {
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		if strings.ContainsAny(r.Header.Get("User"), "internal") {
+			w.Header().Add("UserID", strconv.Itoa(rand.Int()))
+			w.Header().Add("UserRole", "admin")
+			w.Header().Add("Other", "not used")
+			fmt.Fprint(w, "ok")
+		} else {
+			rc := http.StatusForbidden
+			if c := r.URL.Query().Get("code"); len(c) > 0 {
+				c, _ := strconv.Atoi(c)
+				if c > 0 && c < 600 {
+					rc = c
+				}
+			}
+
+			w.WriteHeader(rc)
+			fmt.Fprint(w, "unauthorized")
+		}
+	})
+	http.ListenAndServe(":8080", nil)
+}