Live: broadcast events when dashboard is saved (#27583)

Co-authored-by: kay delaney <45561153+kaydelaney@users.noreply.github.com>
Co-authored-by: Torkel Ödegaard <torkel@grafana.org>

pkg/services/live/pluginHandler.go

@@ -0,0 +1,32 @@
+package live
+
+import (
+	"github.com/centrifugal/centrifuge"
+	"github.com/grafana/grafana/pkg/models"
+	"github.com/grafana/grafana/pkg/plugins"
+)
+
+// PluginHandler manages all the `grafana/dashboard/*` channels
+type PluginHandler struct {
+	Plugin *plugins.PluginBase
+}
+
+// GetHandlerForPath called on init
+func (g *PluginHandler) GetHandlerForPath(path string) (models.ChannelHandler, error) {
+	return g, nil // all dashboards share the same handler
+}
+
+// GetChannelOptions called fast and often
+func (g *PluginHandler) GetChannelOptions(id string) centrifuge.ChannelOptions {
+	return centrifuge.ChannelOptions{}
+}
+
+// OnSubscribe for now allows anyone to subscribe to any dashboard
+func (g *PluginHandler) OnSubscribe(c *centrifuge.Client, e centrifuge.SubscribeEvent) error {
+	return nil // anyone can subscribe
+}
+
+// OnPublish called when an event is received from the websocket
+func (g *PluginHandler) OnPublish(c *centrifuge.Client, e centrifuge.PublishEvent) ([]byte, error) {
+	return e.Data, nil // broadcast any event
+}