Add no-op CensusAgent (#19625)

* Add no-op CensusAgent

* Changelog for Census Agent background worker

changelog/19625.txt

@@ -0,0 +1,4 @@
+```release-note:feature
+core (enterprise): Add background worker for automatic reporting of billing
+information.
+```

vault/activity_log.go

@@ -174,6 +174,14 @@ type ActivityLog struct {
 	partialMonthClientTracker map[string]*activity.EntityRecord
 
 	inprocessExport *atomic.Bool
+
+	// CensusReportDone is a channel used to signal tests upon successful calls
+	// to (CensusReporter).Write() in CensusReport.
+	CensusReportDone chan bool
+
+	// CensusReportInterval is the testing configuration for time between
+	// Write() calls initiated in CensusReport.
+	CensusReportInterval time.Duration
 }
 
 // These non-persistent configuration options allow us to disable
@@ -185,6 +193,9 @@ type ActivityLogCoreConfig struct {
 
 	// Do not start timers to send or persist fragments.
 	DisableTimers bool
+
+	// CensusReportInterval is the testing configuration for time
+	CensusReportInterval time.Duration
 }
 
 // NewActivityLog creates an activity log.
@@ -206,6 +217,7 @@ func NewActivityLog(core *Core, logger log.Logger, view *BarrierView, metrics me
 		writeCh:                   make(chan struct{}, 1), // same for full segment
 		doneCh:                    make(chan struct{}, 1),
 		partialMonthClientTracker: make(map[string]*activity.EntityRecord),
+		CensusReportInterval:      time.Hour * 1,
 
 		currentSegment: segmentInfo{
 			startTimestamp: 0,
@@ -943,6 +955,10 @@ func (a *ActivityLog) SetConfigInit(config activityConfig) {
 
 	a.defaultReportMonths = config.DefaultReportMonths
 	a.retentionMonths = config.RetentionMonths
+
+	if a.configOverrides.CensusReportInterval > 0 {
+		a.CensusReportInterval = a.configOverrides.CensusReportInterval
+	}
 }
 
 // This version reacts to user changes
@@ -1079,6 +1095,9 @@ func (c *Core) setupActivityLog(ctx context.Context, wg *sync.WaitGroup) error {
 			manager.retentionWorker(ctx, time.Now(), months)
 			close(manager.retentionDone)
 		}(manager.retentionMonths)
+
+		manager.CensusReportDone = make(chan bool)
+		go c.activityLog.CensusReport(ctx, c.censusAgent)
 	}
 
 	return nil
@@ -1579,7 +1598,9 @@ func (a *ActivityLog) handleQuery(ctx context.Context, startTime, endTime time.T
 	if computePartial {
 		// Traverse through current month's activitylog data and group clients
 		// into months and namespaces
+		a.fragmentLock.RLock()
 		partialByMonth, partialByNamespace = a.populateNamespaceAndMonthlyBreakdowns()
+		a.fragmentLock.RUnlock()
 
 		// Convert the byNamespace breakdowns into structs that are
 		// consumable by the /activity endpoint, so as to reuse code between these two
@@ -1763,6 +1784,8 @@ type activityConfig struct {
 
 	// Enabled is one of enable, disable, default.
 	Enabled string `json:"enabled"`
+
+	CensusReportInterval time.Duration `json:"census_report_interval"`
 }
 
 func defaultActivityConfig() activityConfig {

vault/activity_log_util.go

@@ -11,3 +11,6 @@ import "context"
 func (a *ActivityLog) sendCurrentFragment(ctx context.Context) error {
 	return nil
 }
+
+// CensusReport is a no-op on OSS
+func (a *ActivityLog) CensusReport(_ctx context.Context, _ca *CensusAgent) {}

vault/census.go

@@ -0,0 +1,6 @@
+//go:build !enterprise
+
+package vault
+
+// CensusAgent is a stub for OSS
+type CensusAgent struct{}

vault/core.go

@@ -641,6 +641,9 @@ type Core struct {
 
 	activityLogConfig ActivityLogCoreConfig
 
+	// censusAgent is the mechanism used for reporting Vault's billing data.
+	censusAgent *CensusAgent
+
 	// activeTime is set on active nodes indicating the time at which this node
 	// became active.
 	activeTime time.Time
@@ -808,6 +811,9 @@ type CoreConfig struct {
 	LicensePath     string
 	LicensingConfig *LicensingConfig
 
+	// Configured Census Agent
+	censusAgent *CensusAgent
+
 	DisablePerformanceStandby bool
 	DisableIndexing           bool
 	DisableKeyEncodingChecks  bool

vault/testing.go

@@ -217,6 +217,7 @@ func TestCoreWithSealAndUINoCleanup(t testing.T, opts *CoreConfig) *Core {
 	conf.PluginDirectory = opts.PluginDirectory
 	conf.DetectDeadlocks = opts.DetectDeadlocks
 	conf.Experiments = []string{experiments.VaultExperimentEventsAlpha1}
+	conf.censusAgent = opts.censusAgent
 
 	if opts.Logger != nil {
 		conf.Logger = opts.Logger