Add API endpoint for listing running servers

server_handlers.go

@@ -0,0 +1,34 @@
+package main
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/hibiken/asynq"
+)
+
+// ****************************************************************************
+// This file defines:
+//   - http.Handler(s) for server related endpoints
+// ****************************************************************************
+
+type ListServersResponse struct {
+	Servers []*ServerInfo `json:"servers"`
+}
+
+func newListServersHandlerFunc(inspector *asynq.Inspector) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		srvs, err := inspector.Servers()
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		resp := ListServersResponse{
+			Servers: toServerInfoList(srvs),
+		}
+		if err := json.NewEncoder(w).Encode(resp); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+	}
+}