state: add vochain_validator metric using NewGaugeVec

vochain/state/validators.go

@@ -6,13 +6,37 @@ import (
 	"fmt"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/prometheus/client_golang/prometheus"
+	"go.vocdoni.io/dvote/log"
+	"go.vocdoni.io/dvote/metrics"
 	"go.vocdoni.io/dvote/tree/arbo"
 	"go.vocdoni.io/proto/build/go/models"
 	"google.golang.org/protobuf/proto"
 )
 
+var promValidator = prometheus.NewGaugeVec(prometheus.GaugeOpts{
+	Namespace: "vochain",
+	Name:      "validator",
+	Help:      "validator stats",
+}, []string{"address"})
+
+func init() {
+	metrics.Register(promValidator)
+}
+
+func updateValidatorMetrics(validator *models.Validator) {
+	log.Warnf("validator %s (%x): %d", validator.GetName(), validator.GetAddress(), validator.GetPower())
+	gauge, err := promValidator.GetMetricWithLabelValues(fmt.Sprintf("%x", validator.GetAddress()))
+	if err != nil {
+		log.Warn(err)
+		return
+	}
+	gauge.Set(float64(validator.GetPower()))
+}
+
 // AddValidator adds a tendemint validator. If it exists, it will be updated.
 func (v *State) AddValidator(validator *models.Validator) error {
+	defer updateValidatorMetrics(validator)
 	v.tx.Lock()
 	defer v.tx.Unlock()
 	validatorBytes, err := proto.Marshal(validator)