implemented observability

internal/events/bus.go

@@ -16,6 +16,7 @@ import (
 type EventBus interface {
 	Publish(subject string, payload any) error
 	Subscribe(subject string, handler func(subject string, data []byte)) (func(), error)
+	Healthy() bool
 	Close()
 }
 
@@ -63,6 +64,8 @@ func (b *NATSBus) Subscribe(subject string, handler func(subject string, data []
 	return func() { sub.Unsubscribe() }, nil //nolint:errcheck
 }
 
+func (b *NATSBus) Healthy() bool { return b.nc.IsConnected() }
+
 func (b *NATSBus) Close() {
 	if err := b.nc.Drain(); err != nil {
 		log.Printf("nats: drain: %v", err)
@@ -75,6 +78,7 @@ type NoOpBus struct{}
 
 func (NoOpBus) Publish(_ string, _ any) error                              { return nil }
 func (NoOpBus) Subscribe(_ string, _ func(string, []byte)) (func(), error) { return func() {}, nil }
+func (NoOpBus) Healthy() bool                                               { return true }
 func (NoOpBus) Close()                                                      {}
 
 // New returns a NATSBus if url is non-empty, otherwise a NoOpBus.