Implement CertRenewEvent (#1879)

caddytls/client.go

@@ -345,6 +345,9 @@ func (c *ACMEClient) Renew(name string) error {
 		return errors.New("too many renewal attempts; last error: " + err.Error())
 	}
 
+	// Executes Cert renew events
+	caddy.EmitEvent(caddy.CertRenewEvent, name)
+
 	return saveCertResource(storage, newCertMeta)
 }
 

plugins.go

@@ -231,10 +231,11 @@ func RegisterPlugin(name string, plugin Plugin) {
 // EventName represents the name of an event used with event hooks.
 type EventName string
 
-// Define the event names for the startup and shutdown events
+// Define names for the various events
 const (
-	StartupEvent  EventName = "startup"
-	ShutdownEvent EventName = "shutdown"
+	StartupEvent   EventName = "startup"
+	ShutdownEvent  EventName = "shutdown"
+	CertRenewEvent EventName = "certrenew"
 )
 
 // EventHook is a type which holds information about a startup hook plugin.