add missing label on replicator metrics and unit test (#229)

The storage type label is missing from metrics blob replicator, causing the initialization to fail on:
panic: 1 unknown label(s) found during currying

goroutine 1 [running]:
github.com/prometheus/client_golang/prometheus.(*HistogramVec).MustCurryWith(...)
external/gazelle~~go_deps~com_github_prometheus_client_golang/prometheus/histogram.go:1278

Also, add a unit test to catch this case.

Author: kevinye202

pkg/blobstore/replication/BUILD.bazel

@@ -41,6 +41,7 @@ go_test(
     srcs = [
         "deduplicating_blob_replicator_test.go",
         "local_blob_replicator_test.go",
+        "metrics_blob_replicator_test.go",
         "nested_blob_replicator_test.go",
         "queued_blob_replicator_test.go",
     ],

pkg/blobstore/replication/metrics_blob_replicator.go

@@ -27,7 +27,7 @@ var (
 			Help:      "Amount of time spent per operation on blob replicator, in seconds.",
 			Buckets:   util.DecimalExponentialBuckets(-3, 6, 2),
 		},
-		[]string{"operation"})
+		[]string{"storage_type", "operation"})
 
 	blobReplicatorOperationsBlobSizeBytes = prometheus.NewHistogramVec(
 		prometheus.HistogramOpts{
@@ -37,7 +37,7 @@ var (
 			Help:      "Size of blobs being replicated, in bytes.",
 			Buckets:   prometheus.ExponentialBuckets(1.0, 2.0, 33),
 		},
-		[]string{"operation"})
+		[]string{"storage_type", "operation"})
 
 	blobReplicatorOperationsBatchSize = prometheus.NewHistogramVec(
 		prometheus.HistogramOpts{
@@ -47,7 +47,7 @@ var (
 			Help:      "Number of blobs in batch replication requests.",
 			Buckets:   prometheus.ExponentialBuckets(1.0, 2.0, 17),
 		},
-		[]string{"operation"})
+		[]string{"storage_type", "operation"})
 )
 
 type metricsBlobReplicator struct {
@@ -78,21 +78,21 @@ func NewMetricsBlobReplicator(replicator BlobReplicator, clock clock.Clock, stor
 		replicator: replicator,
 		clock:      clock,
 		singleDurationSeconds: blobReplicatorOperationsDurationSeconds.MustCurryWith(map[string]string{
-			"operation": "ReplicateSingle",
-			"storage":   storageTypeName,
+			"storage_type": storageTypeName,
+			"operation":    "ReplicateSingle",
 		}),
-		singleBlobSizeBytes: blobReplicatorOperationsBlobSizeBytes.WithLabelValues("ReplicateSingle", storageTypeName),
+		singleBlobSizeBytes: blobReplicatorOperationsBlobSizeBytes.WithLabelValues(storageTypeName, "ReplicateSingle"),
 		compositeDurationSeconds: blobReplicatorOperationsDurationSeconds.MustCurryWith(map[string]string{
-			"operation": "ReplicateComposite",
-			"storage":   storageTypeName,
+			"storage_type": storageTypeName,
+			"operation":    "ReplicateComposite",
 		}),
-		compositeBlobSizeBytes: blobReplicatorOperationsBlobSizeBytes.WithLabelValues("ReplicateComposite", storageTypeName),
+		compositeBlobSizeBytes: blobReplicatorOperationsBlobSizeBytes.WithLabelValues(storageTypeName, "ReplicateComposite"),
 		multipleDurationSeconds: blobReplicatorOperationsDurationSeconds.MustCurryWith(map[string]string{
-			"operation": "ReplicateMultiple",
-			"storage":   storageTypeName,
+			"storage_type": storageTypeName,
+			"operation":    "ReplicateMultiple",
 		}),
-		multipleBlobSizeBytes: blobReplicatorOperationsBlobSizeBytes.WithLabelValues("ReplicateMultiple", storageTypeName),
-		multipleBatchSize:     blobReplicatorOperationsBatchSize.WithLabelValues("ReplicateMultiple", storageTypeName),
+		multipleBlobSizeBytes: blobReplicatorOperationsBlobSizeBytes.WithLabelValues(storageTypeName, "ReplicateMultiple"),
+		multipleBatchSize:     blobReplicatorOperationsBatchSize.WithLabelValues(storageTypeName, "ReplicateMultiple"),
 	}
 }
 

pkg/blobstore/replication/metrics_blob_replicator_test.go

@@ -0,0 +1,25 @@
+package replication_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/buildbarn/bb-storage/internal/mock"
+	"github.com/buildbarn/bb-storage/pkg/blobstore/replication"
+	"go.uber.org/mock/gomock"
+)
+
+func TestNewMetricsBlobReplicator(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	// Create mock using the generated mock
+	mockReplicator := mock.NewMockBlobReplicator(ctrl)
+	mockClock := mock.NewMockClock(ctrl)
+
+	// Create a new MetricsBlobReplicator
+	storageTypeName := "cas"
+	metricsReplicator := replication.NewMetricsBlobReplicator(mockReplicator, mockClock, storageTypeName)
+	require.NotNil(t, metricsReplicator)
+}