Merge branch 'pks-transaction-metrics-refactoring' into 'master'

Refactor setup of transaction metrics

See merge request gitlab-org/gitaly!2474

11 files changed, 111 insertions, 187 deletions

diff --git a/cmd/praefect/main.go b/cmd/praefect/main.go
index 4783279bc..0ffb5b2cf 100644
--- a/cmd/praefect/main.go
+++ b/cmd/praefect/main.go
@@ -243,34 +243,10 @@ func run(cfgs []starter.Config, conf config.Config) error {
 	nodeManager.Start(conf.Failover.BootstrapInterval.Duration(), conf.Failover.MonitorInterval.Duration())
 	logger.Info("background started: gitaly nodes health monitoring")
 
-	transactionCounterMetric, err := metrics.RegisterTransactionCounter()
-	if err != nil {
-		return err
-	}
-
-	transactionDelayMetric, err := metrics.RegisterTransactionDelay(conf.Prometheus)
-	if err != nil {
-		return err
-	}
-
-	subtransactionsHistogram, err := metrics.RegisterSubtransactionsHistogram()
-	if err != nil {
-		return err
-	}
-
-	transactionManager := transactions.NewManager(
-		transactions.WithCounterMetric(transactionCounterMetric),
-		transactions.WithDelayMetric(transactionDelayMetric),
-		transactions.WithSubtransactionsMetric(subtransactionsHistogram),
-	)
-
-	transactionVoters, err := metrics.RegisterTransactionVoters(conf)
-	if err != nil {
-		return err
-	}
-
 	var (
 		// top level server dependencies
+		transactionManager = transactions.NewManager(conf)
+
 		coordinator = praefect.NewCoordinator(
 			queue,
 			rs,
@@ -278,8 +254,8 @@ func run(cfgs []starter.Config, conf config.Config) error {
 			transactionManager,
 			conf,
 			protoregistry.GitalyProtoPreregistered,
-			praefect.WithVotersMetric(transactionVoters),
 		)
+
 		repl = praefect.NewReplMgr(
 			logger,
 			conf.VirtualStorageNames(),
@@ -303,6 +279,8 @@ func run(cfgs []starter.Config, conf config.Config) error {
 	)
 
 	prometheus.MustRegister(
+		transactionManager,
+		coordinator,
 		repl,
 		datastore.NewRepositoryStoreCollector(logger, rs, nodeManager),
 	)
diff --git a/internal/praefect/auth_test.go b/internal/praefect/auth_test.go
index f93589ad9..cfe119a58 100644
--- a/internal/praefect/auth_test.go
+++ b/internal/praefect/auth_test.go
@@ -171,7 +171,7 @@ func runServer(t *testing.T, token string, required bool) (*grpc.Server, string,
 	nodeMgr, err := nodes.NewManager(logEntry, conf, nil, nil, promtest.NewMockHistogramVec())
 	require.NoError(t, err)
 
-	txMgr := transactions.NewManager()
+	txMgr := transactions.NewManager(conf)
 
 	registry, err := protoregistry.New(fd)
 	require.NoError(t, err)
diff --git a/internal/praefect/coordinator.go b/internal/praefect/coordinator.go
index dc0564653..d016a5bb3 100644
--- a/internal/praefect/coordinator.go
+++ b/internal/praefect/coordinator.go
@@ -20,7 +20,6 @@ import (
 	"gitlab.com/gitlab-org/gitaly/internal/praefect/nodes"
 	"gitlab.com/gitlab-org/gitaly/internal/praefect/protoregistry"
 	"gitlab.com/gitlab-org/gitaly/internal/praefect/transactions"
-	prommetrics "gitlab.com/gitlab-org/gitaly/internal/prometheus/metrics"
 	"gitlab.com/gitlab-org/gitaly/proto/go/gitalypb"
 	"gitlab.com/gitlab-org/labkit/correlation"
 	"golang.org/x/sync/errgroup"
@@ -82,7 +81,7 @@ type Coordinator struct {
 	rs           datastore.RepositoryStore
 	registry     *protoregistry.Registry
 	conf         config.Config
-	votersMetric prommetrics.HistogramVec
+	votersMetric *prometheus.HistogramVec
 }
 
 // NewCoordinator returns a new Coordinator that utilizes the provided logger
@@ -93,8 +92,14 @@ func NewCoordinator(
 	txMgr *transactions.Manager,
 	conf config.Config,
 	r *protoregistry.Registry,
-	opts ...CoordinatorOpt,
 ) *Coordinator {
+	maxVoters := 1
+	for _, storage := range conf.VirtualStorages {
+		if len(storage.Nodes) > maxVoters {
+			maxVoters = len(storage.Nodes)
+		}
+	}
+
 	coordinator := &Coordinator{
 		queue:    queue,
 		rs:       rs,
@@ -103,26 +108,24 @@ func NewCoordinator(
 		txMgr:    txMgr,
 		conf:     conf,
 		votersMetric: prometheus.NewHistogramVec(
-			prometheus.HistogramOpts{},
+			prometheus.HistogramOpts{
+				Name:    "gitaly_praefect_voters_per_transaction_total",
+				Help:    "The number of voters a given transaction was created with",
+				Buckets: prometheus.LinearBuckets(1, 1, maxVoters),
+			},
 			[]string{"virtual_storage"},
 		),
 	}
 
-	for _, opt := range opts {
-		opt(coordinator)
-	}
-
 	return coordinator
 }
 
-// CoordinatorOpt is a self referential option for Coordinator
-type CoordinatorOpt func(*Coordinator)
+func (c *Coordinator) Describe(descs chan<- *prometheus.Desc) {
+	prometheus.DescribeByCollect(c, descs)
+}
 
-// WithVotersMetric is an option to set the voters Prometheus metric
-func WithVotersMetric(votersMetric prommetrics.HistogramVec) CoordinatorOpt {
-	return func(coordinator *Coordinator) {
-		coordinator.votersMetric = votersMetric
-	}
+func (c *Coordinator) Collect(metrics chan<- prometheus.Metric) {
+	c.votersMetric.Collect(metrics)
 }
 
 func (c *Coordinator) directRepositoryScopedMessage(ctx context.Context, call grpcCall) (*proxy.StreamParameters, error) {
diff --git a/internal/praefect/coordinator_test.go b/internal/praefect/coordinator_test.go
index e8a4644f4..134360901 100644
--- a/internal/praefect/coordinator_test.go
+++ b/internal/praefect/coordinator_test.go
@@ -92,7 +92,7 @@ func TestStreamDirectorReadOnlyEnforcement(t *testing.T) {
 						}},
 					}, nil
 				}},
-				transactions.NewManager(),
+				transactions.NewManager(conf),
 				conf,
 				protoregistry.GitalyProtoPreregistered,
 			)
@@ -155,7 +155,7 @@ func TestStreamDirectorMutator(t *testing.T) {
 	require.NoError(t, err)
 	nodeMgr.Start(0, time.Hour)
 
-	txMgr := transactions.NewManager()
+	txMgr := transactions.NewManager(conf)
 
 	coordinator := NewCoordinator(
 		queueInterceptor,
@@ -357,7 +357,7 @@ func TestStreamDirectorMutator_Transaction(t *testing.T) {
 				waitNodeToChangeHealthStatus(ctx, t, node, true)
 			}
 
-			txMgr := transactions.NewManager()
+			txMgr := transactions.NewManager(conf)
 
 			// set up the generations prior to transaction
 			rs := datastore.NewMemoryRepositoryStore(conf.StorageNames())
@@ -494,7 +494,7 @@ func TestStreamDirectorAccessor(t *testing.T) {
 	require.NoError(t, err)
 	nodeMgr.Start(0, time.Minute)
 
-	txMgr := transactions.NewManager()
+	txMgr := transactions.NewManager(conf)
 
 	coordinator := NewCoordinator(
 		queue,
@@ -583,7 +583,7 @@ func TestCoordinatorStreamDirector_distributesReads(t *testing.T) {
 	require.NoError(t, err)
 	nodeMgr.Start(0, time.Minute)
 
-	txMgr := transactions.NewManager()
+	txMgr := transactions.NewManager(conf)
 
 	coordinator := NewCoordinator(
 		queue,
@@ -782,7 +782,7 @@ func TestAbsentCorrelationID(t *testing.T) {
 	require.NoError(t, err)
 	nodeMgr.Start(0, time.Hour)
 
-	txMgr := transactions.NewManager()
+	txMgr := transactions.NewManager(conf)
 
 	coordinator := NewCoordinator(
 		queueInterceptor,
diff --git a/internal/praefect/helper_test.go b/internal/praefect/helper_test.go
index 551b55d3c..58107b4be 100644
--- a/internal/praefect/helper_test.go
+++ b/internal/praefect/helper_test.go
@@ -175,7 +175,7 @@ func runPraefectServerWithGitaly(t *testing.T, conf config.Config) (*grpc.Client
 func runPraefectServerWithGitalyWithDatastore(t *testing.T, conf config.Config, queue datastore.ReplicationEventQueue) (*grpc.ClientConn, *grpc.Server, testhelper.Cleanup) {
 	return runPraefectServer(t, conf, buildOptions{
 		withQueue:    queue,
-		withTxMgr:    transactions.NewManager(),
+		withTxMgr:    transactions.NewManager(conf),
 		withBackends: withRealGitalyShared(t),
 	})
 }
@@ -184,8 +184,8 @@ func defaultQueue(conf config.Config) datastore.ReplicationEventQueue {
 	return datastore.NewMemoryReplicationEventQueue(conf)
 }
 
-func defaultTxMgr() *transactions.Manager {
-	return transactions.NewManager()
+func defaultTxMgr(conf config.Config) *transactions.Manager {
+	return transactions.NewManager(conf)
 }
 
 func defaultNodeMgr(t testing.TB, conf config.Config, rs datastore.RepositoryStore) nodes.Manager {
@@ -209,7 +209,7 @@ func runPraefectServer(t testing.TB, conf config.Config, opt buildOptions) (*grp
 		opt.withRepoStore = defaultRepoStore(conf)
 	}
 	if opt.withTxMgr == nil {
-		opt.withTxMgr = defaultTxMgr()
+		opt.withTxMgr = defaultTxMgr(conf)
 	}
 	if opt.withBackends != nil {
 		cleanups = append(cleanups, opt.withBackends(conf.VirtualStorages)...)
diff --git a/internal/praefect/metrics/prometheus.go b/internal/praefect/metrics/prometheus.go
index fc26eaad8..dbb97ca02 100644
--- a/internal/praefect/metrics/prometheus.go
+++ b/internal/praefect/metrics/prometheus.go
@@ -3,7 +3,6 @@ package metrics
 import (
 	"github.com/prometheus/client_golang/prometheus"
 	promconfig "gitlab.com/gitlab-org/gitaly/internal/config/prometheus"
-	"gitlab.com/gitlab-org/gitaly/internal/praefect/config"
 	"gitlab.com/gitlab-org/gitaly/internal/prometheus/metrics"
 )
 
@@ -54,71 +53,6 @@ func RegisterNodeLatency(conf promconfig.Config) (metrics.HistogramVec, error) {
 	return nodeLatency, prometheus.Register(nodeLatency)
 }
 
-// RegisterTransactionCounter creates and registers a Prometheus counter to
-// track the number of transactions and their outcomes.
-func RegisterTransactionCounter() (*prometheus.CounterVec, error) {
-	transactionCounter := prometheus.NewCounterVec(
-		prometheus.CounterOpts{
-			Namespace: "gitaly",
-			Subsystem: "praefect",
-			Name:      "transactions_total",
-			Help:      "Total number of transaction actions",
-		},
-		[]string{"action"},
-	)
-	return transactionCounter, prometheus.Register(transactionCounter)
-}
-
-// RegisterTransactionDelay creates and registers a Prometheus histogram to
-// track the delay of actions performed on transactions.
-func RegisterTransactionDelay(conf promconfig.Config) (metrics.HistogramVec, error) {
-	transactionDelay := prometheus.NewHistogramVec(
-		prometheus.HistogramOpts{
-			Namespace: "gitaly",
-			Subsystem: "praefect",
-			Name:      "transactions_delay_seconds",
-			Help:      "Delay between casting a vote and reaching quorum",
-			Buckets:   conf.GRPCLatencyBuckets,
-		},
-		[]string{"action"},
-	)
-	return transactionDelay, prometheus.Register(transactionDelay)
-}
-
-// RegisterSubtransactionsHistogram creates and registers a Prometheus counter to
-// gauge the number of subtransactions per transaction.
-func RegisterSubtransactionsHistogram() (metrics.Histogram, error) {
-	subtransactionsHistogram := prometheus.NewHistogram(
-		prometheus.HistogramOpts{
-			Name:    "gitaly_praefect_subtransactions_per_transaction_total",
-			Help:    "The number of subtransactions created for a single registered transaction",
-			Buckets: []float64{0.0, 1.0, 2.0, 4.0, 8.0, 16.0, 32.0},
-		},
-	)
-	return subtransactionsHistogram, prometheus.Register(subtransactionsHistogram)
-}
-
-// RegisterTransactionVoters creates and registers a Prometheus counter to gauge
-// the number of voters per transaction.
-func RegisterTransactionVoters(conf config.Config) (metrics.HistogramVec, error) {
-	maxVoters := 0
-	for _, storage := range conf.VirtualStorages {
-		if len(storage.Nodes) > maxVoters {
-			maxVoters = len(storage.Nodes)
-		}
-	}
-
-	transactionVoters := prometheus.NewHistogramVec(
-		prometheus.HistogramOpts{
-			Name:    "gitaly_praefect_voters_per_transaction_total",
-			Help:    "The number of voters a given transaction was created with",
-			Buckets: prometheus.LinearBuckets(0, 1, maxVoters),
-		},
-		[]string{"virtual_storage"},
-	)
-	return transactionVoters, prometheus.Register(transactionVoters)
-}
-
 var MethodTypeCounter = prometheus.NewCounterVec(
 	prometheus.CounterOpts{
 		Namespace: "gitaly",
diff --git a/internal/praefect/replicator_test.go b/internal/praefect/replicator_test.go
index ee8aaf464..9d98a3e7b 100644
--- a/internal/praefect/replicator_test.go
+++ b/internal/praefect/replicator_test.go
@@ -226,7 +226,7 @@ func TestPropagateReplicationJob(t *testing.T) {
 	require.NoError(t, err)
 	nodeMgr.Start(0, time.Hour)
 
-	txMgr := transactions.NewManager()
+	txMgr := transactions.NewManager(conf)
 
 	rs := datastore.NewMemoryRepositoryStore(conf.StorageNames())
 
diff --git a/internal/praefect/server_factory_test.go b/internal/praefect/server_factory_test.go
index 293659c46..a453ef718 100644
--- a/internal/praefect/server_factory_test.go
+++ b/internal/praefect/server_factory_test.go
@@ -82,7 +82,7 @@ func TestServerFactory(t *testing.T) {
 	nodeMgr, err := nodes.NewManager(logger, conf, nil, datastore.NewMemoryRepositoryStore(conf.StorageNames()), &promtest.MockHistogramVec{})
 	require.NoError(t, err)
 	nodeMgr.Start(0, time.Second)
-	txMgr := transactions.NewManager()
+	txMgr := transactions.NewManager(conf)
 	registry := protoregistry.GitalyProtoPreregistered
 	rs := datastore.NewMemoryRepositoryStore(conf.StorageNames())
 	coordinator := NewCoordinator(queue, rs, nodeMgr, txMgr, conf, registry)
diff --git a/internal/praefect/server_test.go b/internal/praefect/server_test.go
index 696c31acb..0df9fdf93 100644
--- a/internal/praefect/server_test.go
+++ b/internal/praefect/server_test.go
@@ -748,7 +748,7 @@ func newGrpcServer(t *testing.T, srv gitalypb.SmartHTTPServiceServer) (string, *
 }
 
 func TestProxyWrites(t *testing.T) {
-	txMgr := transactions.NewManager()
+	txMgr := transactions.NewManager(config.Config{})
 
 	smartHTTP0, smartHTTP1, smartHTTP2 := &mockSmartHTTP{txMgr: txMgr}, &mockSmartHTTP{txMgr: txMgr}, &mockSmartHTTP{txMgr: txMgr}
 
diff --git a/internal/praefect/transaction_test.go b/internal/praefect/transaction_test.go
index e997157a6..71f5e3bc0 100644
--- a/internal/praefect/transaction_test.go
+++ b/internal/praefect/transaction_test.go
@@ -1,16 +1,17 @@
 package praefect
 
 import (
+	"bytes"
 	"crypto/sha1"
 	"fmt"
 	"sync"
 	"testing"
 	"time"
 
-	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/testutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"gitlab.com/gitlab-org/gitaly/internal/praefect/config"
 	"gitlab.com/gitlab-org/gitaly/internal/praefect/transactions"
 	"gitlab.com/gitlab-org/gitaly/internal/testhelper"
 	"gitlab.com/gitlab-org/gitaly/proto/go/gitalypb"
@@ -26,9 +27,9 @@ type voter struct {
 	shouldSucceed bool
 }
 
-func runPraefectServerAndTxMgr(t testing.TB, opts ...transactions.ManagerOpt) (*grpc.ClientConn, *transactions.Manager, testhelper.Cleanup) {
+func runPraefectServerAndTxMgr(t testing.TB) (*grpc.ClientConn, *transactions.Manager, testhelper.Cleanup) {
 	conf := testConfig(1)
-	txMgr := transactions.NewManager(opts...)
+	txMgr := transactions.NewManager(conf)
 	cc, _, cleanup := runPraefectServer(t, conf, buildOptions{
 		withTxMgr:   txMgr,
 		withNodeMgr: nullNodeMgr{}, // to suppress node address issues
@@ -36,40 +37,38 @@ func runPraefectServerAndTxMgr(t testing.TB, opts ...transactions.ManagerOpt) (*
 	return cc, txMgr, cleanup
 }
 
-func setupMetrics() (*prometheus.CounterVec, []transactions.ManagerOpt) {
-	counter := prometheus.NewCounterVec(prometheus.CounterOpts{}, []string{"status"})
-	return counter, []transactions.ManagerOpt{
-		transactions.WithCounterMetric(counter),
-	}
-}
-
 type counterMetrics struct {
 	registered, started, invalid, committed int
 }
 
-func verifyCounterMetrics(t *testing.T, counter *prometheus.CounterVec, expected counterMetrics) {
+func verifyCounterMetrics(t *testing.T, manager *transactions.Manager, expected counterMetrics) {
 	t.Helper()
 
-	registered, err := counter.GetMetricWithLabelValues("registered")
-	require.NoError(t, err)
-	require.Equal(t, float64(expected.registered), testutil.ToFloat64(registered))
-
-	started, err := counter.GetMetricWithLabelValues("started")
-	require.NoError(t, err)
-	require.Equal(t, float64(expected.started), testutil.ToFloat64(started))
+	metrics := []struct {
+		name  string
+		value int
+	}{
+		{"registered", expected.registered},
+		{"started", expected.started},
+		{"invalid", expected.invalid},
+		{"committed", expected.committed},
+	}
 
-	invalid, err := counter.GetMetricWithLabelValues("invalid")
-	require.NoError(t, err)
-	require.Equal(t, float64(expected.invalid), testutil.ToFloat64(invalid))
+	var expectedMetric bytes.Buffer
+	expectedMetric.WriteString("# HELP gitaly_praefect_transactions_total Total number of transaction actions\n")
+	expectedMetric.WriteString("# TYPE gitaly_praefect_transactions_total counter\n")
+	for _, metric := range metrics {
+		if metric.value == 0 {
+			continue
+		}
+		expectedMetric.WriteString(fmt.Sprintf("gitaly_praefect_transactions_total{action=\"%s\"} %d\n", metric.name, metric.value))
+	}
 
-	committed, err := counter.GetMetricWithLabelValues("committed")
-	require.NoError(t, err)
-	require.Equal(t, float64(expected.committed), testutil.ToFloat64(committed))
+	require.NoError(t, testutil.CollectAndCompare(manager, &expectedMetric, "gitaly_praefect_transactions_total"))
 }
 
 func TestTransactionSucceeds(t *testing.T) {
-	counter, opts := setupMetrics()
-	cc, txMgr, cleanup := runPraefectServerAndTxMgr(t, opts...)
+	cc, txMgr, cleanup := runPraefectServerAndTxMgr(t)
 	defer cleanup()
 
 	ctx, cancel := testhelper.Context(testhelper.ContextWithTimeout(time.Second))
@@ -95,7 +94,7 @@ func TestTransactionSucceeds(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, gitalypb.VoteTransactionResponse_COMMIT, response.State)
 
-	verifyCounterMetrics(t, counter, counterMetrics{
+	verifyCounterMetrics(t, txMgr, counterMetrics{
 		registered: 1,
 		started:    1,
 		committed:  1,
@@ -249,7 +248,7 @@ func TestTransactionRegistrationWithInvalidNodesFails(t *testing.T) {
 	ctx, cleanup := testhelper.Context()
 	defer cleanup()
 
-	txMgr := transactions.NewManager()
+	txMgr := transactions.NewManager(config.Config{})
 
 	_, _, err := txMgr.RegisterTransaction(ctx, []transactions.Voter{}, 1)
 	require.Equal(t, transactions.ErrMissingNodes, err)
@@ -298,7 +297,7 @@ func TestTransactionRegistrationWithInvalidThresholdFails(t *testing.T) {
 	ctx, cleanup := testhelper.Context()
 	defer cleanup()
 
-	txMgr := transactions.NewManager()
+	txMgr := transactions.NewManager(config.Config{})
 
 	for _, tc := range tc {
 		t.Run(tc.desc, func(t *testing.T) {
@@ -552,8 +551,7 @@ func TestTransactionWithMultipleVotes(t *testing.T) {
 }
 
 func TestTransactionFailures(t *testing.T) {
-	counter, opts := setupMetrics()
-	cc, _, cleanup := runPraefectServerAndTxMgr(t, opts...)
+	cc, txMgr, cleanup := runPraefectServerAndTxMgr(t)
 	defer cleanup()
 
 	ctx, cancel := testhelper.Context(testhelper.ContextWithTimeout(time.Second))
@@ -570,7 +568,7 @@ func TestTransactionFailures(t *testing.T) {
 	require.Error(t, err)
 	require.Equal(t, codes.NotFound, status.Code(err))
 
-	verifyCounterMetrics(t, counter, counterMetrics{
+	verifyCounterMetrics(t, txMgr, counterMetrics{
 		started: 1,
 		invalid: 1,
 	})
@@ -623,8 +621,7 @@ func TestTransactionCancellation(t *testing.T) {
 
 	for _, tc := range testcases {
 		t.Run(tc.desc, func(t *testing.T) {
-			counter, opts := setupMetrics()
-			cc, txMgr, cleanup := runPraefectServerAndTxMgr(t, opts...)
+			cc, txMgr, cleanup := runPraefectServerAndTxMgr(t)
 			defer cleanup()
 
 			ctx, cancel := testhelper.Context(testhelper.ContextWithTimeout(time.Second))
@@ -679,7 +676,7 @@ func TestTransactionCancellation(t *testing.T) {
 				require.Equal(t, results[fmt.Sprintf("node-%d", i)], v.shouldSucceed, "result mismatches expected node state")
 			}
 
-			verifyCounterMetrics(t, counter, tc.expectedMetrics)
+			verifyCounterMetrics(t, txMgr, tc.expectedMetrics)
 		})
 	}
 }
diff --git a/internal/praefect/transactions/manager.go b/internal/praefect/transactions/manager.go
index c3527db16..b663c4827 100644
--- a/internal/praefect/transactions/manager.go
+++ b/internal/praefect/transactions/manager.go
@@ -14,7 +14,7 @@ import (
 	"github.com/grpc-ecosystem/go-grpc-middleware/logging/logrus/ctxlogrus"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/sirupsen/logrus"
-	"gitlab.com/gitlab-org/gitaly/internal/prometheus/metrics"
+	"gitlab.com/gitlab-org/gitaly/internal/praefect/config"
 )
 
 var ErrNotFound = errors.New("transaction not found")
@@ -27,8 +27,8 @@ type Manager struct {
 	lock                  sync.Mutex
 	transactions          map[uint64]*Transaction
 	counterMetric         *prometheus.CounterVec
-	delayMetric           metrics.HistogramVec
-	subtransactionsMetric metrics.Histogram
+	delayMetric           *prometheus.HistogramVec
+	subtransactionsMetric prometheus.Histogram
 }
 
 // TransactionIDGenerator is an interface for types that can generate transaction IDs.
@@ -61,27 +61,6 @@ func (t *transactionIDGenerator) ID() uint64 {
 // ManagerOpt is a self referential option for Manager
 type ManagerOpt func(*Manager)
 
-// WithCounterMetric is an option to set the counter Prometheus metric
-func WithCounterMetric(counterMetric *prometheus.CounterVec) ManagerOpt {
-	return func(mgr *Manager) {
-		mgr.counterMetric = counterMetric
-	}
-}
-
-// WithDelayMetric is an option to set the delay Prometheus metric
-func WithDelayMetric(delayMetric metrics.HistogramVec) ManagerOpt {
-	return func(mgr *Manager) {
-		mgr.delayMetric = delayMetric
-	}
-}
-
-// WithSubtransactionsMetric is an option to set the subtransactions Prometheus metric
-func WithSubtransactionsMetric(subtransactionsMetric metrics.Histogram) ManagerOpt {
-	return func(mgr *Manager) {
-		mgr.subtransactionsMetric = subtransactionsMetric
-	}
-}
-
 // WithTransactionIDGenerator is an option to set the transaction ID generator
 func WithTransactionIDGenerator(generator TransactionIDGenerator) ManagerOpt {
 	return func(mgr *Manager) {
@@ -90,13 +69,36 @@ func WithTransactionIDGenerator(generator TransactionIDGenerator) ManagerOpt {
 }
 
 // NewManager creates a new transactions Manager.
-func NewManager(opts ...ManagerOpt) *Manager {
+func NewManager(cfg config.Config, opts ...ManagerOpt) *Manager {
 	mgr := &Manager{
-		txIDGenerator:         newTransactionIDGenerator(),
-		transactions:          make(map[uint64]*Transaction),
-		counterMetric:         prometheus.NewCounterVec(prometheus.CounterOpts{}, []string{"action"}),
-		delayMetric:           prometheus.NewHistogramVec(prometheus.HistogramOpts{}, []string{"action"}),
-		subtransactionsMetric: prometheus.NewHistogram(prometheus.HistogramOpts{}),
+		txIDGenerator: newTransactionIDGenerator(),
+		transactions:  make(map[uint64]*Transaction),
+		counterMetric: prometheus.NewCounterVec(
+			prometheus.CounterOpts{
+				Namespace: "gitaly",
+				Subsystem: "praefect",
+				Name:      "transactions_total",
+				Help:      "Total number of transaction actions",
+			},
+			[]string{"action"},
+		),
+		delayMetric: prometheus.NewHistogramVec(
+			prometheus.HistogramOpts{
+				Namespace: "gitaly",
+				Subsystem: "praefect",
+				Name:      "transactions_delay_seconds",
+				Help:      "Delay between casting a vote and reaching quorum",
+				Buckets:   cfg.Prometheus.GRPCLatencyBuckets,
+			},
+			[]string{"action"},
+		),
+		subtransactionsMetric: prometheus.NewHistogram(
+			prometheus.HistogramOpts{
+				Name:    "gitaly_praefect_subtransactions_per_transaction_total",
+				Help:    "The number of subtransactions created for a single registered transaction",
+				Buckets: []float64{0.0, 1.0, 2.0, 4.0, 8.0, 16.0, 32.0},
+			},
+		),
 	}
 
 	for _, opt := range opts {
@@ -106,6 +108,16 @@ func NewManager(opts ...ManagerOpt) *Manager {
 	return mgr
 }
 
+func (mgr *Manager) Describe(descs chan<- *prometheus.Desc) {
+	prometheus.DescribeByCollect(mgr, descs)
+}
+
+func (mgr *Manager) Collect(metrics chan<- prometheus.Metric) {
+	mgr.counterMetric.Collect(metrics)
+	mgr.delayMetric.Collect(metrics)
+	mgr.subtransactionsMetric.Collect(metrics)
+}
+
 func (mgr *Manager) log(ctx context.Context) logrus.FieldLogger {
 	return ctxlogrus.Extract(ctx).WithField("component", "transactions.Manager")
 }