diff --git a/vendor/github.com/prometheus/client_golang/prometheus/value.go b/vendor/github.com/prometheus/client_golang/prometheus/value.go
index eb248f1..c778711 100644
--- a/vendor/github.com/prometheus/client_golang/prometheus/value.go
+++ b/vendor/github.com/prometheus/client_golang/prometheus/value.go
@@ -16,8 +16,12 @@
 import (
 	"fmt"
 	"sort"
+	"time"
+	"unicode/utf8"
 
+	//nolint:staticcheck // Ignore SA1019. Need to keep deprecated package for compatibility.
 	"github.com/golang/protobuf/proto"
+	"github.com/golang/protobuf/ptypes"
 
 	dto "github.com/prometheus/client_model/go"
 )
@@ -25,7 +29,8 @@
 // ValueType is an enumeration of metric types that represent a simple value.
 type ValueType int
 
-// Possible values for the ValueType enum.
+// Possible values for the ValueType enum. Use UntypedValue to mark a metric
+// with an unknown type.
 const (
 	_ ValueType = iota
 	CounterValue
@@ -58,7 +63,7 @@
 		desc:       desc,
 		valType:    valueType,
 		function:   function,
-		labelPairs: makeLabelPairs(desc, nil),
+		labelPairs: MakeLabelPairs(desc, nil),
 	}
 	result.init(result)
 	return result
@@ -69,7 +74,7 @@
 }
 
 func (v *valueFunc) Write(out *dto.Metric) error {
-	return populateMetric(v.valType, v.function(), v.labelPairs, out)
+	return populateMetric(v.valType, v.function(), v.labelPairs, nil, out)
 }
 
 // NewConstMetric returns a metric with one fixed value that cannot be
@@ -90,7 +95,7 @@
 		desc:       desc,
 		valType:    valueType,
 		val:        value,
-		labelPairs: makeLabelPairs(desc, labelValues),
+		labelPairs: MakeLabelPairs(desc, labelValues),
 	}, nil
 }
 
@@ -116,19 +121,20 @@
 }
 
 func (m *constMetric) Write(out *dto.Metric) error {
-	return populateMetric(m.valType, m.val, m.labelPairs, out)
+	return populateMetric(m.valType, m.val, m.labelPairs, nil, out)
 }
 
 func populateMetric(
 	t ValueType,
 	v float64,
 	labelPairs []*dto.LabelPair,
+	e *dto.Exemplar,
 	m *dto.Metric,
 ) error {
 	m.Label = labelPairs
 	switch t {
 	case CounterValue:
-		m.Counter = &dto.Counter{Value: proto.Float64(v)}
+		m.Counter = &dto.Counter{Value: proto.Float64(v), Exemplar: e}
 	case GaugeValue:
 		m.Gauge = &dto.Gauge{Value: proto.Float64(v)}
 	case UntypedValue:
@@ -139,7 +145,14 @@
 	return nil
 }
 
-func makeLabelPairs(desc *Desc, labelValues []string) []*dto.LabelPair {
+// MakeLabelPairs is a helper function to create protobuf LabelPairs from the
+// variable and constant labels in the provided Desc. The values for the
+// variable labels are defined by the labelValues slice, which must be in the
+// same order as the corresponding variable labels in the Desc.
+//
+// This function is only needed for custom Metric implementations. See MetricVec
+// example.
+func MakeLabelPairs(desc *Desc, labelValues []string) []*dto.LabelPair {
 	totalLen := len(desc.variableLabels) + len(desc.constLabelPairs)
 	if totalLen == 0 {
 		// Super fast path.
@@ -160,3 +173,40 @@
 	sort.Sort(labelPairSorter(labelPairs))
 	return labelPairs
 }
+
+// ExemplarMaxRunes is the max total number of runes allowed in exemplar labels.
+const ExemplarMaxRunes = 64
+
+// newExemplar creates a new dto.Exemplar from the provided values. An error is
+// returned if any of the label names or values are invalid or if the total
+// number of runes in the label names and values exceeds ExemplarMaxRunes.
+func newExemplar(value float64, ts time.Time, l Labels) (*dto.Exemplar, error) {
+	e := &dto.Exemplar{}
+	e.Value = proto.Float64(value)
+	tsProto, err := ptypes.TimestampProto(ts)
+	if err != nil {
+		return nil, err
+	}
+	e.Timestamp = tsProto
+	labelPairs := make([]*dto.LabelPair, 0, len(l))
+	var runes int
+	for name, value := range l {
+		if !checkLabelName(name) {
+			return nil, fmt.Errorf("exemplar label name %q is invalid", name)
+		}
+		runes += utf8.RuneCountInString(name)
+		if !utf8.ValidString(value) {
+			return nil, fmt.Errorf("exemplar label value %q is not valid UTF-8", value)
+		}
+		runes += utf8.RuneCountInString(value)
+		labelPairs = append(labelPairs, &dto.LabelPair{
+			Name:  proto.String(name),
+			Value: proto.String(value),
+		})
+	}
+	if runes > ExemplarMaxRunes {
+		return nil, fmt.Errorf("exemplar labels have %d runes, exceeding the limit of %d", runes, ExemplarMaxRunes)
+	}
+	e.Label = labelPairs
+	return e, nil
+}