@@ -7,6 +7,7 @@ ethCommon "github.com/ethereum/go-ethereum/common"
 	"github.com/gin-gonic/gin"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 	"github.com/hermeznetwork/hermez-node/db/l2db"
+	"github.com/hermeznetwork/hermez-node/metric"
 	"github.com/hermeznetwork/tracerr"
 )
 
@@ -49,6 +50,12 @@ l2:            l2db,
 		chainID:       consts.ChainID,
 		hermezAddress: consts.HermezAddress,
 	}
+
+	middleware, err := metric.PrometheusMiddleware()
+	if err != nil {
+		return nil, err
+	}
+	server.Use(middleware)
 
 	v1 := server.Group("/v1")
 

@@ -8,6 +8,7 @@
 	"github.com/gin-gonic/gin"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 	"github.com/hermeznetwork/hermez-node/log"
+	"github.com/hermeznetwork/hermez-node/metric"
 	"github.com/hermeznetwork/tracerr"
 	"github.com/lib/pq"
 	"github.com/russross/meddler"
@@ -46,7 +47,9 @@ )
 
 func retSQLErr(err error, c *gin.Context) {
 	log.Warnw("HTTP API SQL request error", "err", err)
-	errMsg := tracerr.Unwrap(err).Error()
+	unwrapErr := tracerr.Unwrap(err)
+	metric.CollectError(unwrapErr)
+	errMsg := unwrapErr.Error()
 	retDupKey := func(errCode pq.ErrorCode) {
 		// https://www.postgresql.org/docs/current/errcodes-appendix.html
 		if errCode == "23505" {
@@ -80,6 +83,7 @@ }
 
 func retBadReq(err error, c *gin.Context) {
 	log.Warnw("HTTP API Bad request error", "err", err)
+	metric.CollectError(err)
 	c.JSON(http.StatusBadRequest, errorMsg{
 		Message: err.Error(),
 	})

@@ -35,7 +35,7 @@ Symbol = "SUSHI"
 Addr = "0x6b3595068778dd592e39a122f4f5a5cf09c90fe2"
 
 [Debug]
-APIAddress = "localhost:12345"
+APIAddress = "0.0.0.0:12345"
 MeddlerLogs = true
 GinDebugMode = true
 

@@ -80,6 +80,7 @@ type BatchInfo struct {
 	PipelineNum           int
 	BatchNum              common.BatchNum
 	ServerProof           prover.Client
+	ProofStart            time.Time
 	ZKInputs              *common.ZKInputs
 	Proof                 *prover.Proof
 	PublicInputs          []*big.Int

@@ -5,6 +5,7 @@ "context"
 	"database/sql"
 	"fmt"
 	"math/big"
+	"strconv"
 	"sync"
 	"time"
 
@@ -14,6 +15,7 @@ "github.com/hermeznetwork/hermez-node/db/historydb"
 	"github.com/hermeznetwork/hermez-node/db/l2db"
 	"github.com/hermeznetwork/hermez-node/eth"
 	"github.com/hermeznetwork/hermez-node/log"
+	"github.com/hermeznetwork/hermez-node/metric"
 	"github.com/hermeznetwork/hermez-node/prover"
 	"github.com/hermeznetwork/hermez-node/synchronizer"
 	"github.com/hermeznetwork/hermez-node/txselector"
@@ -246,6 +248,7 @@ }
 
 	// 3. Send the ZKInputs to the proof server
 	batchInfo.ServerProof = serverProof
+	batchInfo.ProofStart = time.Now()
 	if err := p.sendServerProof(ctx, batchInfo); ctx.Err() != nil {
 		return nil, ctx.Err()
 	} else if err != nil {
@@ -602,6 +605,9 @@ }
 
 // waitServerProof gets the generated zkProof & sends it to the SmartContract
 func (p *Pipeline) waitServerProof(ctx context.Context, batchInfo *BatchInfo) error {
+	defer metric.MeasureDuration(metric.WaitServerProof, batchInfo.ProofStart,
+		batchInfo.BatchNum.BigInt().String(), strconv.Itoa(batchInfo.PipelineNum))
+
 	proof, pubInputs, err := batchInfo.ServerProof.GetProof(ctx) // blocking call,
 	// until not resolved don't continue. Returns when the proof server has calculated the proof
 	if err != nil {

@@ -0,0 +1,192 @@
+package metric
+
+import (
+	"time"
+
+	"github.com/hermeznetwork/hermez-node/log"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type (
+	// Metric represents the metric type
+	Metric string
+)
+
+const (
+	namespaceError      = "error"
+	namespaceSync       = "synchronizer"
+	namespaceTxSelector = "txselector"
+	namespaceAPI        = "api"
+)
+
+var (
+	// Errors errors count metric.
+	Errors = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Namespace: namespaceError,
+			Name:      "errors",
+			Help:      "",
+		}, []string{"error"})
+
+	// WaitServerProof duration time to get the calculated
+	// proof from the server.
+	WaitServerProof = prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Namespace: namespaceSync,
+			Name:      "wait_server_proof",
+			Help:      "",
+		}, []string{"batch_number", "pipeline_number"})
+
+	// Reorgs block reorg count
+	Reorgs = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Namespace: namespaceSync,
+			Name:      "reorgs",
+			Help:      "",
+		})
+
+	// LastBlockNum last block synced
+	LastBlockNum = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Namespace: namespaceSync,
+			Name:      "synced_last_block_num",
+			Help:      "",
+		})
+
+	// EthLastBlockNum last eth block synced
+	EthLastBlockNum = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Namespace: namespaceSync,
+			Name:      "eth_last_block_num",
+			Help:      "",
+		})
+
+	// LastBatchNum last batch synced
+	LastBatchNum = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Namespace: namespaceSync,
+			Name:      "synced_last_batch_num",
+			Help:      "",
+		})
+
+	// EthLastBatchNum last eth batch synced
+	EthLastBatchNum = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Namespace: namespaceSync,
+			Name:      "eth_last_batch_num",
+			Help:      "",
+		})
+
+	// GetL2TxSelection L2 tx selection count
+	GetL2TxSelection = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Namespace: namespaceTxSelector,
+			Name:      "get_l2_txselection_total",
+			Help:      "",
+		})
+
+	// GetL1L2TxSelection L1L2 tx selection count
+	GetL1L2TxSelection = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Namespace: namespaceTxSelector,
+			Name:      "get_l1_l2_txselection_total",
+			Help:      "",
+		})
+
+	// SelectedL1CoordinatorTxs selected L1 coordinator tx count
+	SelectedL1CoordinatorTxs = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Namespace: namespaceTxSelector,
+			Name:      "selected_l1_coordinator_txs",
+			Help:      "",
+		})
+
+	// SelectedL1UserTxs selected L1 user tx count
+	SelectedL1UserTxs = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Namespace: namespaceTxSelector,
+			Name:      "selected_l1_user_txs",
+			Help:      "",
+		})
+
+	// SelectedL2Txs selected L2 tx count
+	SelectedL2Txs = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Namespace: namespaceTxSelector,
+			Name:      "selected_l2_txs",
+			Help:      "",
+		})
+
+	// DiscardedL2Txs discarded L2 tx count
+	DiscardedL2Txs = prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Namespace: namespaceTxSelector,
+			Name:      "discarded_l2_txs",
+			Help:      "",
+		})
+)
+
+func init() {
+	if err := registerCollectors(); err != nil {
+		log.Error(err)
+	}
+}
+func registerCollectors() error {
+	if err := registerCollector(Errors); err != nil {
+		return err
+	}
+	if err := registerCollector(WaitServerProof); err != nil {
+		return err
+	}
+	if err := registerCollector(Reorgs); err != nil {
+		return err
+	}
+	if err := registerCollector(LastBlockNum); err != nil {
+		return err
+	}
+	if err := registerCollector(LastBatchNum); err != nil {
+		return err
+	}
+	if err := registerCollector(EthLastBlockNum); err != nil {
+		return err
+	}
+	if err := registerCollector(EthLastBatchNum); err != nil {
+		return err
+	}
+	if err := registerCollector(GetL2TxSelection); err != nil {
+		return err
+	}
+	if err := registerCollector(GetL1L2TxSelection); err != nil {
+		return err
+	}
+	if err := registerCollector(SelectedL1CoordinatorTxs); err != nil {
+		return err
+	}
+	if err := registerCollector(SelectedL1UserTxs); err != nil {
+		return err
+	}
+	return registerCollector(DiscardedL2Txs)
+}
+
+func registerCollector(collector prometheus.Collector) error {
+	err := prometheus.Register(collector)
+	if err != nil {
+		if _, ok := err.(prometheus.AlreadyRegisteredError); !ok {
+			return err
+		}
+	}
+	return nil
+}
+
+// MeasureDuration measure the method execution duration
+// and save it into a histogram metric
+func MeasureDuration(histogram *prometheus.HistogramVec, start time.Time, lvs ...string) {
+	duration := time.Since(start)
+	histogram.WithLabelValues(lvs...).Observe(float64(duration.Milliseconds()))
+}
+
+// CollectError collect the error message and increment
+// the error count
+func CollectError(err error) {
+	Errors.With(map[string]string{"error": err.Error()}).Inc()
+}

@@ -0,0 +1,78 @@
+package metric
+
+import (
+	"strconv"
+	"time"
+
+	"github.com/gin-gonic/gin"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const (
+	favicon = "/favicon.ico"
+)
+
+// Prometheus contains the metrics gathered by the instance and its path
+type Prometheus struct {
+	reqCnt *prometheus.CounterVec
+	reqDur *prometheus.HistogramVec
+}
+
+// NewPrometheus generates a new set of metrics with a certain subsystem name
+func NewPrometheus() (*Prometheus, error) {
+	reqCnt := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Namespace: namespaceAPI,
+			Name:      "requests_total",
+			Help:      "How many HTTP requests processed, partitioned by status code and HTTP method",
+		},
+		[]string{"code", "method", "path"},
+	)
+	if err := registerCollector(reqCnt); err != nil {
+		return nil, err
+	}
+	reqDur := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Namespace: namespaceAPI,
+			Name:      "request_duration_seconds",
+			Help:      "The HTTP request latencies in seconds",
+		},
+		[]string{"code", "method", "path"},
+	)
+	if err := registerCollector(reqDur); err != nil {
+		return nil, err
+	}
+	return &Prometheus{
+		reqCnt: reqCnt,
+		reqDur: reqDur,
+	}, nil
+}
+
+// PrometheusMiddleware creates the prometheus collector and
+// defines status handler function for the middleware
+func PrometheusMiddleware() (gin.HandlerFunc, error) {
+	p, err := NewPrometheus()
+	if err != nil {
+		return nil, err
+	}
+	return p.Middleware(), nil
+}
+
+// Middleware defines status handler function for middleware
+func (p *Prometheus) Middleware() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		if c.Request.URL.Path == favicon {
+			c.Next()
+			return
+		}
+		start := time.Now()
+		c.Next()
+
+		status := strconv.Itoa(c.Writer.Status())
+		elapsed := float64(time.Since(start)) / float64(time.Second)
+		fullPath := c.FullPath()
+
+		p.reqDur.WithLabelValues(status, c.Request.Method, fullPath).Observe(elapsed)
+		p.reqCnt.WithLabelValues(status, c.Request.Method, fullPath).Inc()
+	}
+}

@@ -1,44 +0,0 @@
-package synchronizer
-
-import "github.com/prometheus/client_golang/prometheus"
-
-var (
-	metricReorgsCount = prometheus.NewCounter(
-		prometheus.CounterOpts{
-			Name: "sync_reorgs",
-			Help: "",
-		},
-	)
-	metricSyncedLastBlockNum = prometheus.NewGauge(
-		prometheus.GaugeOpts{
-			Name: "sync_synced_last_block_num",
-			Help: "",
-		},
-	)
-	metricEthLastBlockNum = prometheus.NewGauge(
-		prometheus.GaugeOpts{
-			Name: "sync_eth_last_block_num",
-			Help: "",
-		},
-	)
-	metricSyncedLastBatchNum = prometheus.NewGauge(
-		prometheus.GaugeOpts{
-			Name: "sync_synced_last_batch_num",
-			Help: "",
-		},
-	)
-	metricEthLastBatchNum = prometheus.NewGauge(
-		prometheus.GaugeOpts{
-			Name: "sync_eth_last_batch_num",
-			Help: "",
-		},
-	)
-)
-
-func init() {
-	prometheus.MustRegister(metricReorgsCount)
-	prometheus.MustRegister(metricSyncedLastBlockNum)
-	prometheus.MustRegister(metricEthLastBlockNum)
-	prometheus.MustRegister(metricSyncedLastBatchNum)
-	prometheus.MustRegister(metricEthLastBatchNum)
-}

@@ -47,6 +47,7 @@ "github.com/hermeznetwork/hermez-node/db/l2db"
 	"github.com/hermeznetwork/hermez-node/db/statedb"
 	"github.com/hermeznetwork/hermez-node/eth"
 	"github.com/hermeznetwork/hermez-node/log"
+	"github.com/hermeznetwork/hermez-node/metric"
 	"github.com/hermeznetwork/hermez-node/txprocessor"
 	"github.com/hermeznetwork/tracerr"
 )
@@ -581,6 +582,7 @@ if err != nil {
 				return nil, nil, tracerr.Wrap(err)
 			}
 			discarded := lastSavedBlock.Num - lastDBBlockNum
+			metric.Reorgs.Inc()
 			return nil, &discarded, nil
 		}
 	}
@@ -673,16 +675,16 @@ return nil, nil, tracerr.Wrap(err)
 	}
 
 	for _, batchData := range rollupData.Batches {
-		metricSyncedLastBatchNum.Set(float64(batchData.Batch.BatchNum))
-		metricEthLastBatchNum.Set(float64(s.stats.Eth.LastBatchNum))
+		metric.LastBatchNum.Set(float64(batchData.Batch.BatchNum))
+		metric.EthLastBatchNum.Set(float64(s.stats.Eth.LastBatchNum))
 		log.Debugw("Synced batch",
 			"syncLastBatch", batchData.Batch.BatchNum,
 			"syncBatchesPerc", s.stats.batchesPerc(batchData.Batch.BatchNum),
 			"ethLastBatch", s.stats.Eth.LastBatchNum,
 		)
 	}
-	metricSyncedLastBlockNum.Set(float64(s.stats.Sync.LastBlock.Num))
-	metricEthLastBlockNum.Set(float64(s.stats.Eth.LastBlock.Num))
+	metric.LastBlockNum.Set(float64(s.stats.Sync.LastBlock.Num))
+	metric.EthLastBlockNum.Set(float64(s.stats.Eth.LastBlock.Num))
 	log.Debugw("Synced block",
 		"syncLastBlockNum", s.stats.Sync.LastBlock.Num,
 		"syncBlocksPerc", s.stats.blocksPerc(),

@@ -1,53 +0,0 @@
-package txselector
-
-import "github.com/prometheus/client_golang/prometheus"
-
-var (
-	metricGetL2TxSelection = prometheus.NewCounter(
-		prometheus.CounterOpts{
-			Name: "txsel_get_l2_txselecton_total",
-			Help: "",
-		},
-	)
-	metricGetL1L2TxSelection = prometheus.NewCounter(
-		prometheus.CounterOpts{
-			Name: "txsel_get_l1_l2_txselecton_total",
-			Help: "",
-		},
-	)
-
-	metricSelectedL1CoordinatorTxs = prometheus.NewGauge(
-		prometheus.GaugeOpts{
-			Name: "txsel_selected_l1_coordinator_txs",
-			Help: "",
-		},
-	)
-	metricSelectedL1UserTxs = prometheus.NewGauge(
-		prometheus.GaugeOpts{
-			Name: "txsel_selected_l1_user_txs",
-			Help: "",
-		},
-	)
-	metricSelectedL2Txs = prometheus.NewGauge(
-		prometheus.GaugeOpts{
-			Name: "txsel_selected_l2_txs",
-			Help: "",
-		},
-	)
-	metricDiscardedL2Txs = prometheus.NewGauge(
-		prometheus.GaugeOpts{
-			Name: "txsel_discarded_l2_txs",
-			Help: "",
-		},
-	)
-)
-
-func init() {
-	prometheus.MustRegister(metricGetL2TxSelection)
-	prometheus.MustRegister(metricGetL1L2TxSelection)
-
-	prometheus.MustRegister(metricSelectedL1CoordinatorTxs)
-	prometheus.MustRegister(metricSelectedL1UserTxs)
-	prometheus.MustRegister(metricSelectedL2Txs)
-	prometheus.MustRegister(metricDiscardedL2Txs)
-}

@@ -13,6 +13,7 @@ "github.com/hermeznetwork/hermez-node/db/kvdb"
 	"github.com/hermeznetwork/hermez-node/db/l2db"
 	"github.com/hermeznetwork/hermez-node/db/statedb"
 	"github.com/hermeznetwork/hermez-node/log"
+	"github.com/hermeznetwork/hermez-node/metric"
 	"github.com/hermeznetwork/hermez-node/txprocessor"
 	"github.com/hermeznetwork/tracerr"
 	"github.com/iden3/go-iden3-crypto/babyjub"
@@ -123,7 +124,7 @@ // creation exists. The L1UserTxs, L1CoordinatorTxs, PoolL2Txs that will be
 // included in the next batch.
 func (txsel *TxSelector) GetL2TxSelection(selectionConfig txprocessor.Config) ([]common.Idx,
 	[][]byte, []common.L1Tx, []common.PoolL2Tx, []common.PoolL2Tx, error) {
-	metricGetL2TxSelection.Inc()
+	metric.GetL2TxSelection.Inc()
 	coordIdxs, accCreationAuths, _, l1CoordinatorTxs, l2Txs,
 		discardedL2Txs, err := txsel.getL1L2TxSelection(selectionConfig, []common.L1Tx{})
 	return coordIdxs, accCreationAuths, l1CoordinatorTxs, l2Txs,
@@ -141,7 +142,7 @@ // included in the next batch.
 func (txsel *TxSelector) GetL1L2TxSelection(selectionConfig txprocessor.Config,
 	l1UserTxs []common.L1Tx) ([]common.Idx, [][]byte, []common.L1Tx,
 	[]common.L1Tx, []common.PoolL2Tx, []common.PoolL2Tx, error) {
-	metricGetL1L2TxSelection.Inc()
+	metric.GetL1L2TxSelection.Inc()
 	coordIdxs, accCreationAuths, l1UserTxs, l1CoordinatorTxs, l2Txs,
 		discardedL2Txs, err := txsel.getL1L2TxSelection(selectionConfig, l1UserTxs)
 	return coordIdxs, accCreationAuths, l1UserTxs, l1CoordinatorTxs, l2Txs,
@@ -221,10 +222,11 @@ if err != nil {
 			return nil, nil, nil, nil, nil, nil, tracerr.Wrap(err)
 		}
 
-		metricSelectedL1UserTxs.Set(float64(len(l1UserTxs)))
-		metricSelectedL1CoordinatorTxs.Set(0)
-		metricSelectedL2Txs.Set(0)
-		metricDiscardedL2Txs.Set(float64(len(discardedL2Txs)))
+		metric.SelectedL1UserTxs.Set(float64(len(l1UserTxs)))
+		metric.SelectedL1CoordinatorTxs.Set(0)
+		metric.SelectedL2Txs.Set(0)
+		metric.DiscardedL2Txs.Set(float64(len(discardedL2Txs)))
+
 		return nil, nil, l1UserTxs, nil, nil, discardedL2Txs, nil
 	}
 
@@ -320,10 +322,10 @@ if err != nil {
 		return nil, nil, nil, nil, nil, nil, tracerr.Wrap(err)
 	}
 
-	metricSelectedL1UserTxs.Set(float64(len(l1UserTxs)))
-	metricSelectedL1CoordinatorTxs.Set(float64(len(l1CoordinatorTxs)))
-	metricSelectedL2Txs.Set(float64(len(validTxs)))
-	metricDiscardedL2Txs.Set(float64(len(discardedL2Txs)))
+	metric.SelectedL1CoordinatorTxs.Set(float64(len(l1CoordinatorTxs)))
+	metric.SelectedL1UserTxs.Set(float64(len(l1UserTxs)))
+	metric.SelectedL2Txs.Set(float64(len(validTxs)))
+	metric.DiscardedL2Txs.Set(float64(len(discardedL2Txs)))
 
 	return coordIdxs, accAuths, l1UserTxs, l1CoordinatorTxs, validTxs, discardedL2Txs, nil
 }