Fix some lint errors (#3334)

I left the promql ones and some others untouched as I remember that @fabxc
prefers them that way.

discovery/triton/triton.go

@@ -32,11 +32,11 @@ import (
 
 const (
 	tritonLabel             = model.MetaLabelPrefix + "triton_"
-	tritonLabelMachineId    = tritonLabel + "machine_id"
+	tritonLabelMachineID    = tritonLabel + "machine_id"
 	tritonLabelMachineAlias = tritonLabel + "machine_alias"
 	tritonLabelMachineBrand = tritonLabel + "machine_brand"
 	tritonLabelMachineImage = tritonLabel + "machine_image"
-	tritonLabelServerId     = tritonLabel + "server_id"
+	tritonLabelServerID     = tritonLabel + "server_id"
 	namespace               = "prometheus"
 )
 
@@ -58,6 +58,7 @@ func init() {
 	prometheus.MustRegister(refreshDuration)
 }
 
+// DiscoveryResponse models a JSON response from the Triton discovery.
 type DiscoveryResponse struct {
 	Containers []struct {
 		ServerUUID  string `json:"server_uuid"`
@@ -169,11 +170,11 @@ func (d *Discovery) refresh() (tg *config.TargetGroup, err error) {
 
 	for _, container := range dr.Containers {
 		labels := model.LabelSet{
-			tritonLabelMachineId:    model.LabelValue(container.VMUUID),
+			tritonLabelMachineID:    model.LabelValue(container.VMUUID),
 			tritonLabelMachineAlias: model.LabelValue(container.VMAlias),
 			tritonLabelMachineBrand: model.LabelValue(container.VMBrand),
 			tritonLabelMachineImage: model.LabelValue(container.VMImageUUID),
-			tritonLabelServerId:     model.LabelValue(container.ServerUUID),
+			tritonLabelServerID:     model.LabelValue(container.ServerUUID),
 		}
 		addr := fmt.Sprintf("%s.%s:%d", container.VMUUID, d.sdConfig.DNSSuffix, d.sdConfig.Port)
 		labels[model.AddressLabel] = model.LabelValue(addr)

pkg/labels/labels.go

@@ -64,10 +64,12 @@ func (ls Labels) String() string {
 	return b.String()
 }
 
+// MarshalJSON implements json.Marshaler.
 func (ls Labels) MarshalJSON() ([]byte, error) {
 	return json.Marshal(ls.Map())
 }
 
+// UnmarshalJSON implements json.Unmarshaler.
 func (ls *Labels) UnmarshalJSON(b []byte) error {
 	var m map[string]string
 
@@ -187,7 +189,7 @@ func Compare(a, b Labels) int {
 	return len(a) - len(b)
 }
 
-// LabelsBuilder allows modifiying Labels.
+// Builder allows modifiying Labels.
 type Builder struct {
 	base Labels
 	del  []string

pkg/textparse/lex.l

@@ -92,7 +92,7 @@ M     [a-zA-Z_:]
                                       l.offsets = append(l.offsets, l.i)
 <lstateLValueIn>(\\.|[^\\"])*\"       l.state = lstateLabels
                                       if !utf8.Valid(l.b[l.offsets[len(l.offsets)-1]:l.i-1]) {
-                                        l.err = fmt.Errorf("Invalid UTF-8 label value.")
+                                        l.err = fmt.Errorf("invalid UTF-8 label value")
                                         return -1
                                       }
                                       l.offsets = append(l.offsets, l.i-1)

pkg/textparse/lex.l.go

@@ -1,4 +1,4 @@
-// CAUTION: Generated file - DO NOT EDIT.
+// Code generated by golex. DO NOT EDIT.
 
 // Copyright 2017 The Prometheus Authors
 // Licensed under the Apache License, Version 2.0 (the "License");
@@ -492,7 +492,7 @@ yyrule14: // (\\.|[^\\"])*\"
 	{
 		l.state = lstateLabels
 		if !utf8.Valid(l.b[l.offsets[len(l.offsets)-1] : l.i-1]) {
-			l.err = fmt.Errorf("Invalid UTF-8 label value.")
+			l.err = fmt.Errorf("invalid UTF-8 label value")
 			return -1
 		}
 		l.offsets = append(l.offsets, l.i-1)

pkg/textparse/parse_test.go

@@ -172,7 +172,7 @@ func TestParseErrors(t *testing.T) {
 		},
 		{
 			input: "a{b=\"\xff\"} 1\n",
-			err:   "Invalid UTF-8 label value.",
+			err:   "invalid UTF-8 label value",
 		},
 		{
 			input: "a true\n",

pkg/value/value.go

@@ -18,16 +18,17 @@ import (
 )
 
 const (
-	// A quiet NaN. This is also math.NaN().
+	// NormalNaN is a quiet NaN. This is also math.NaN().
 	NormalNaN uint64 = 0x7ff8000000000001
 
-	// A signalling NaN, due to the MSB of the mantissa being 0.
+	// StaleNaN is a signalling NaN, due to the MSB of the mantissa being 0.
 	// This value is chosen with many leading 0s, so we have scope to store more
 	// complicated values in the future. It is 2 rather than 1 to make
 	// it easier to distinguish from the NormalNaN by a human when debugging.
 	StaleNaN uint64 = 0x7ff0000000000002
 )
 
+// IsStaleNaN returns true when the provided NaN value is a stale marker.
 func IsStaleNaN(v float64) bool {
 	return math.Float64bits(v) == StaleNaN
 }

storage/remote/read.go

@@ -207,6 +207,7 @@ func newConcreteSeriersIterator(series *concreteSeries) storage.SeriesIterator {
 	}
 }
 
+// Seek implements storage.SeriesIterator.
 func (c *concreteSeriesIterator) Seek(t int64) bool {
 	c.cur = sort.Search(len(c.series.samples), func(n int) bool {
 		return c.series.samples[n].Timestamp >= t
@@ -214,16 +215,19 @@ func (c *concreteSeriesIterator) Seek(t int64) bool {
 	return c.cur < len(c.series.samples)
 }
 
+// At implements storage.SeriesIterator.
 func (c *concreteSeriesIterator) At() (t int64, v float64) {
 	s := c.series.samples[c.cur]
 	return s.Timestamp, s.Value
 }
 
+// Next implements storage.SeriesIterator.
 func (c *concreteSeriesIterator) Next() bool {
 	c.cur++
 	return c.cur < len(c.series.samples)
 }
 
+// Err implements storage.SeriesIterator.
 func (c *concreteSeriesIterator) Err() error {
 	return nil
 }

storage/remote/write.go

@@ -19,10 +19,12 @@ import (
 	"github.com/prometheus/prometheus/storage"
 )
 
+// Appender implements retrieval.Appendable.
 func (s *Storage) Appender() (storage.Appender, error) {
 	return s, nil
 }
 
+// Add implements storage.Appender.
 func (s *Storage) Add(l labels.Labels, t int64, v float64) (uint64, error) {
 	s.mtx.RLock()
 	defer s.mtx.RUnlock()
@@ -44,15 +46,18 @@ func labelsToMetric(ls labels.Labels) model.Metric {
 	return metric
 }
 
+// AddFast implements storage.Appender.
 func (s *Storage) AddFast(l labels.Labels, _ uint64, t int64, v float64) error {
 	_, err := s.Add(l, t, v)
 	return err
 }
 
+// Commit implements storage.Appender.
 func (*Storage) Commit() error {
 	return nil
 }
 
+// Rollback implements storage.Appender.
 func (*Storage) Rollback() error {
 	return nil
 }

util/treecache/treecache.go

@@ -45,20 +45,23 @@ func init() {
 	prometheus.MustRegister(numWatchers)
 }
 
+// ZookeeperLogger wraps a log.Logger into a zk.Logger.
 type ZookeeperLogger struct {
 	logger log.Logger
 }
 
-// NewZookeeperLogger is a constructor for ZookeeperLogger
+// NewZookeeperLogger is a constructor for ZookeeperLogger.
 func NewZookeeperLogger(logger log.Logger) ZookeeperLogger {
 	return ZookeeperLogger{logger: logger}
 }
 
-// Implements zk.Logger
+// Printf implements zk.Logger.
 func (zl ZookeeperLogger) Printf(s string, i ...interface{}) {
 	level.Info(zl.logger).Log("msg", fmt.Sprintf(s, i...))
 }
 
+// A ZookeeperTreeCache keeps data from all children of a Zookeeper path
+// locally cached and updated according to received events.
 type ZookeeperTreeCache struct {
 	conn     *zk.Conn
 	prefix   string
@@ -70,6 +73,7 @@ type ZookeeperTreeCache struct {
 	logger log.Logger
 }
 
+// A ZookeeperTreeCacheEvent models a Zookeeper event for a path.
 type ZookeeperTreeCacheEvent struct {
 	Path string
 	Data *[]byte
@@ -83,6 +87,7 @@ type zookeeperTreeCacheNode struct {
 	children map[string]*zookeeperTreeCacheNode
 }
 
+// NewZookeeperTreeCache creates a new ZookeeperTreeCache for a given path.
 func NewZookeeperTreeCache(conn *zk.Conn, path string, events chan ZookeeperTreeCacheEvent, logger log.Logger) *ZookeeperTreeCache {
 	tc := &ZookeeperTreeCache{
 		conn:   conn,
@@ -101,6 +106,7 @@ func NewZookeeperTreeCache(conn *zk.Conn, path string, events chan ZookeeperTree
 	return tc
 }
 
+// Stop stops the tree cache.
 func (tc *ZookeeperTreeCache) Stop() {
 	tc.stop <- struct{}{}
 }