feat: custom monitoring

Signed-off-by: huanggze <loganhuang@yunify.com>

pkg/models/monitoring/expressions/registry.go

@@ -0,0 +1,9 @@
+package expressions
+
+type labelReplaceFn func(expr, ns string) (string, error)
+
+var ReplaceNamespaceFns = make(map[string]labelReplaceFn)
+
+func Register(name string, fn labelReplaceFn) {
+	ReplaceNamespaceFns[name] = fn
+}