VAULT-38228 CE side of sighup for observations (#31384)

* VAULT-38228 CE side of sighup for observations

* reload CE

command/server.go

@@ -2304,6 +2304,15 @@ func (c *ServerCommand) Reload(lock *sync.RWMutex, reloadFuncs *map[string][]rel
 					}
 				}
 			}
+
+		case strings.HasPrefix(k, "observations|"):
+			for _, relFunc := range relFuncs {
+				if relFunc != nil {
+					if err := relFunc(); err != nil {
+						reloadErrors = multierror.Append(reloadErrors, fmt.Errorf("error encountered reloading observation system with ledger at path %q: %w", strings.TrimPrefix(k, "observations|"), err))
+					}
+				}
+			}
 		}
 	}
 

vault/core.go

@@ -1394,12 +1394,10 @@ func NewCore(conf *CoreConfig) (*Core, error) {
 				LocalNodeId:             nodeID,
 				Logger:                  observationsLogger,
 			}
-			observations, err := observations.NewObservationSystem(config)
+			err = c.AddObservationSystemToCore(config)
 			if err != nil {
 				return nil, err
 			}
-			c.observations = observations
-			c.observations.Start()
 		}
 	}
 
@@ -1407,6 +1405,30 @@ func NewCore(conf *CoreConfig) (*Core, error) {
 	return c, nil
 }
 
+func (c *Core) AddObservationSystemToCore(config *observations.NewObservationSystemConfig) error {
+	observations, err := observations.NewObservationSystem(config)
+	if err != nil {
+		return err
+	}
+	c.observations = observations
+
+	c.reloadFuncsLock.Lock()
+
+	// While it's only possible to configure one observation system now, making the key
+	// include the path future-proofs us going forward.
+	key := "observations|" + config.LedgerPath
+	c.reloadFuncs[key] = append(c.reloadFuncs[key], func() error {
+		config.Logger.Info("reloading observation system", "path", config.LedgerPath)
+		return observations.Reload()
+	})
+
+	c.reloadFuncsLock.Unlock()
+
+	c.observations.Start()
+
+	return nil
+}
+
 // configureListeners configures the Core with the listeners from the CoreConfig.
 func (c *Core) configureListeners(conf *CoreConfig) error {
 	c.clusterListener.Store((*cluster.Listener)(nil))

vault/observations/observations_ce.go

@@ -34,3 +34,7 @@ func (observations *ObservationSystem) RecordObservationToLedger(_ context.Conte
 func NewObservationSystem(_ *NewObservationSystemConfig) (*ObservationSystem, error) {
 	return &ObservationSystem{}, nil
 }
+
+func (observations *ObservationSystem) Reload() error {
+	return nil
+}