schema/notify: prio.Priority

A uint number between 0 and 255, representing the new priority of the
associated INSTANCE. In newer versions of the VRRP protocol (v2+) a
instance's priority must be 255 to be considered MASTER, but older
versions only require the highest current priority to be MASTER.

This field is also _optional_ keepalived will only output it for VRRP
events, and then only if a setting is enabled in the conf file,
'vrrp_notify_priority_changes'.

  TYPE INSTANCE STATE PRIORITY
                      ^^^^^^^^

schema/notify/prio/flags.go

@@ -0,0 +1,30 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+package prio
+
+import (
+	"strconv"
+	"strings"
+)
+
+const (
+	NULL   Priority = 0
+	MASTER Priority = 255
+)
+
+func ParsePriority(i string) Priority {
+	i = strings.TrimSpace(i)
+
+	p, err := strconv.ParseUint(i, 10, 8)
+	if err != nil {
+		return NULL
+	}
+
+	return Priority(p)
+}
+
+type Priority uint8