add metric for current kvstore version

module/metrics.go

@@ -498,6 +498,8 @@ type ComplianceMetrics interface {
 	EpochFallbackModeTriggered()
 	// EpochFallbackModeExited reports that EFM is no longer triggered.
 	EpochFallbackModeExited()
+	// ProtocolKVStoreVersion reports the latest finalized protocol state KVStore version.
+	ProtocolKVStoreVersion(version uint64)
 }
 
 type CleanerMetrics interface {

module/metrics/compliance.go

@@ -27,6 +27,7 @@ type ComplianceCollector struct {
 	currentDKGPhase2FinalView  prometheus.Gauge
 	currentDKGPhase3FinalView  prometheus.Gauge
 	epochFallbackModeTriggered prometheus.Gauge
+	protocolKVStoreVersion     prometheus.Gauge
 }
 
 var _ module.ComplianceMetrics = (*ComplianceCollector)(nil)
@@ -148,6 +149,13 @@ func NewComplianceCollector() *ComplianceCollector {
 			Subsystem: subsystemCompliance,
 			Help:      "indicates whether epoch fallback mode is triggered; if >0, the fallback is triggered",
 		}),
+
+		protocolKVStoreVersion: promauto.NewGauge(prometheus.GaugeOpts{
+			Name:      "protocol_kv_store_version",
+			Namespace: namespaceConsensus,
+			Subsystem: subsystemCompliance,
+			Help:      "reports the protocol state version of the latest finalized block",
+		}),
 	}
 
 	return cc
@@ -214,3 +222,7 @@ func (cc *ComplianceCollector) EpochFallbackModeTriggered() {
 func (cc *ComplianceCollector) EpochFallbackModeExited() {
 	cc.epochFallbackModeTriggered.Set(float64(0))
 }
+
+func (cc *ComplianceCollector) ProtocolKVStoreVersion(version uint64) {
+	cc.protocolKVStoreVersion.Set(float64(version))
+}

module/metrics/noop.go

@@ -99,6 +99,7 @@ func (nc *NoopCollector) CurrentDKGPhaseViews(phase1FinalView, phase2FinalView,
 }
 func (nc *NoopCollector) EpochFallbackModeTriggered()                                    {}
 func (nc *NoopCollector) EpochFallbackModeExited()                                       {}
+func (nc *NoopCollector) ProtocolKVStoreVersion(version uint64)                          {}
 func (nc *NoopCollector) CacheEntries(resource string, entries uint)                     {}
 func (nc *NoopCollector) CacheHit(resource string)                                       {}
 func (nc *NoopCollector) CacheNotFound(resource string)                                  {}

state/protocol/badger/mutator.go

@@ -805,6 +805,11 @@ func (m *FollowerState) Finalize(ctx context.Context, blockID flow.Identifier) e
 		}
 		m.metrics.BlockSealed(sealedBlock)
 	}
+	protocolSnapshot, err := m.protocolKVStoreSnapshotsDB.ByID(block.Payload.ProtocolStateID)
+	if err != nil {
+		return fmt.Errorf("could not retrieve protocol snapshot for block (%x): %w", blockID, err)
+	}
+	m.metrics.ProtocolKVStoreVersion(protocolSnapshot.Version)
 
 	// apply all queued metrics
 	for _, updateMetric := range metrics {

state/protocol/badger/mutator_test.go

@@ -830,6 +830,7 @@ func TestExtendEpochTransitionValid(t *testing.T) {
 		metrics.On("SealedHeight", mock.Anything)
 		metrics.On("FinalizedHeight", mock.Anything)
 		metrics.On("BlockFinalized", mock.Anything)
+		metrics.On("ProtocolKVStoreVersion", mock.Anything)
 
 		// expect epoch metric calls on bootstrap
 		initialCurrentEpoch := rootSnapshot.Epochs().Current()
@@ -3222,6 +3223,7 @@ func mockMetricsForRootSnapshot(metricsMock *mockmodule.ComplianceMetrics, rootS
 	metricsMock.On("CurrentDKGPhaseViews", epochSetup.DKGPhase1FinalView, epochSetup.DKGPhase2FinalView, epochSetup.DKGPhase3FinalView)
 	metricsMock.On("BlockSealed", mock.Anything)
 	metricsMock.On("BlockFinalized", mock.Anything)
+	metricsMock.On("ProtocolKVStoreVersion", mock.Anything)
 	metricsMock.On("FinalizedHeight", mock.Anything)
 	metricsMock.On("SealedHeight", mock.Anything)
 }