add trigger event idea.

events/external.go

@@ -0,0 +1,21 @@
+package events
+
+import "fmt"
+
+type ExternalEvent struct {
+	Kind   string
+	Values map[string]string
+}
+
+func (e ExternalEvent) EventDescription() string {
+	return fmt.Sprintf("External(kind:%s, values:%v)", e.Kind, e.Values)
+}
+
+func (e ExternalEvent) TriggerKind() string {
+	return fmt.Sprintf("external.%s", e.Kind)
+}
+
+func (e ExternalEvent) TriggerValue(key string) (string, bool) {
+	v, ok := e.Values[key]
+	return v, ok
+}