Add ScalingTarget to Routes API response (#541)

README.md

@@ -564,6 +564,14 @@ If the client reports "Connection refused" check:
 * `GET /routes` (with `Accept: application/json`)
 
   Retrieves the currently configured routes
+  ```json
+  {
+    "serverAddress": {
+      "backend": "HOST:PORT", // The address the client is routed to
+      "scalingTarget": "HOST:PORT" // The address of the actual minecraft server (will differ from backend when a proxy is configured)
+    }
+  }
+  ```
 
 * `POST /routes` (with `Content-Type: application/json`)
 

server/api_server.go

@@ -1,6 +1,7 @@
 package server
 
 import (
+	"context"
 	"encoding/json"
 	"expvar"
 	"net/http"
@@ -37,8 +38,19 @@ func registerApiRoutes(apiRoutes *mux.Router) {
 }
 
 func routesListHandler(writer http.ResponseWriter, _ *http.Request) {
+	type serverRoute = struct {
+		Backend       string `json:"backend"`
+		ScalingTarget string `json:"scalingTarget"`
+	}
+
 	mappings := Routes.GetMappings()
-	bytes, err := json.Marshal(mappings)
+	routes := make(map[string]serverRoute, len(mappings))
+	for k := range mappings {
+		backend, address, scalingTarget, _, _ := Routes.FindBackendForServerAddress(context.Background(), k)
+		routes[address] = serverRoute{Backend: backend, ScalingTarget: scalingTarget}
+	}
+
+	bytes, err := json.Marshal(routes)
 	if err != nil {
 		logrus.WithError(err).Error("Failed to marshal mappings")
 		writer.WriteHeader(http.StatusInternalServerError)