go: add a handler for admin endpoint(s)

app/routes.go

@@ -3,6 +3,7 @@ package app
 import (
 	"net/http"
 
+	"git.dotya.ml/mirre-mt/pcmt/handlers"
 	"github.com/labstack/echo/v4"
 )
 
@@ -15,4 +16,7 @@ func (a *App) SetupRoutes() {
 	e.HEAD("/", func(c echo.Context) error {
 		return c.NoContent(http.StatusOK)
 	})
+
+	// administrative endpoints.
+	e.GET("/admin", handlers.Admin())
 }

handlers/handlers.go

@@ -0,0 +1,13 @@
+package handlers
+
+import (
+	"net/http"
+
+	"github.com/labstack/echo/v4"
+)
+
+func Admin() echo.HandlerFunc {
+	return func(c echo.Context) error {
+		return echo.NewHTTPError(http.StatusUnauthorized, "Invalid credentials")
+	}
+}