Fix most golint warnings.

This is with `golint -min_confidence=0.5`.

I left several lint warnings untouched because they were either
incorrect or I felt it was better not to change them at the moment.

cmd/prometheus/main.go

@@ -46,6 +46,7 @@ func main() {
 	os.Exit(Main())
 }
 
+// Main manages the startup and shutdown lifecycle of the entire Prometheus server.
 func Main() int {
 	if err := parse(os.Args[1:]); err != nil {
 		return 2

config/config.go

@@ -68,19 +68,19 @@ func LoadFile(filename string) (*Config, error) {
 
 // The defaults applied before parsing the respective config sections.
 var (
-	// The default top-level configuration.
+	// DefaultConfig is the default top-level configuration.
 	DefaultConfig = Config{
 		GlobalConfig: DefaultGlobalConfig,
 	}
 
-	// The default global configuration.
+	// DefaultGlobalConfig is the default global configuration.
 	DefaultGlobalConfig = GlobalConfig{
 		ScrapeInterval:     Duration(1 * time.Minute),
 		ScrapeTimeout:      Duration(10 * time.Second),
 		EvaluationInterval: Duration(1 * time.Minute),
 	}
 
-	// The default scrape configuration.
+	// DefaultScrapeConfig is the default scrape configuration.
 	DefaultScrapeConfig = ScrapeConfig{
 		// ScrapeTimeout and ScrapeInterval default to the
 		// configured globals.
@@ -89,30 +89,30 @@ var (
 		HonorLabels: false,
 	}
 
-	// The default Relabel configuration.
+	// DefaultRelabelConfig is the default Relabel configuration.
 	DefaultRelabelConfig = RelabelConfig{
 		Action:    RelabelReplace,
 		Separator: ";",
 	}
 
-	// The default DNS SD configuration.
+	// DefaultDNSSDConfig is the default DNS SD configuration.
 	DefaultDNSSDConfig = DNSSDConfig{
 		RefreshInterval: Duration(30 * time.Second),
 		Type:            "SRV",
 	}
 
-	// The default file SD configuration.
+	// DefaultFileSDConfig is the default file SD configuration.
 	DefaultFileSDConfig = FileSDConfig{
 		RefreshInterval: Duration(5 * time.Minute),
 	}
 
-	// The default Consul SD configuration.
+	// DefaultConsulSDConfig is the default Consul SD configuration.
 	DefaultConsulSDConfig = ConsulSDConfig{
 		TagSeparator: ",",
 		Scheme:       "http",
 	}
 
-	// The default Serverset SD configuration.
+	// DefaultServersetSDConfig is the default Serverset SD configuration.
 	DefaultServersetSDConfig = ServersetSDConfig{
 		Timeout: Duration(10 * time.Second),
 	}
@@ -122,7 +122,7 @@ var (
 		RefreshInterval: Duration(30 * time.Second),
 	}
 
-	// The default Kubernetes SD configuration
+	// DefaultKubernetesSDConfig is the default Kubernetes SD configuration
 	DefaultKubernetesSDConfig = KubernetesSDConfig{
 		KubeletPort:    10255,
 		RequestTimeout: Duration(10 * time.Second),
@@ -130,7 +130,7 @@ var (
 	}
 )
 
-// This custom URL type allows validating at configuration load time.
+// URL is a custom URL type that allows validation at configuration load time.
 type URL struct {
 	*url.URL
 }
@@ -633,6 +633,7 @@ func (c *MarathonSDConfig) UnmarshalYAML(unmarshal func(interface{}) error) erro
 	return checkOverflow(c.XXX, "marathon_sd_config")
 }
 
+// UnmarshalYAML implements the yaml.Unmarshaler interface.
 func (c *KubernetesSDConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	*c = DefaultKubernetesSDConfig
 	type plain KubernetesSDConfig
@@ -655,15 +656,15 @@ func (c *KubernetesSDConfig) UnmarshalYAML(unmarshal func(interface{}) error) er
 type RelabelAction string
 
 const (
-	// Performs a regex replacement.
+	// RelabelReplace performs a regex replacement.
 	RelabelReplace RelabelAction = "replace"
-	// Drops targets for which the input does not match the regex.
+	// RelabelKeep drops targets for which the input does not match the regex.
 	RelabelKeep RelabelAction = "keep"
-	// Drops targets for which the input does match the regex.
+	// RelabelDrop drops targets for which the input does match the regex.
 	RelabelDrop RelabelAction = "drop"
-	// Sets a label to the modulus of a hash of labels.
+	// RelabelHashMod sets a label to the modulus of a hash of labels.
 	RelabelHashMod RelabelAction = "hashmod"
-	// Copy labels to other labelnames based on a regex.
+	// RelabelLabelMap copies labels to other labelnames based on a regex.
 	RelabelLabelMap RelabelAction = "labelmap"
 )
 

promql/ast.go

@@ -179,7 +179,6 @@ func (e *ParenExpr) Type() model.ValueType      { return e.Expr.Type() }
 func (e *StringLiteral) Type() model.ValueType  { return model.ValString }
 func (e *UnaryExpr) Type() model.ValueType      { return e.Expr.Type() }
 func (e *VectorSelector) Type() model.ValueType { return model.ValVector }
-
 func (e *BinaryExpr) Type() model.ValueType {
 	if e.LHS.Type() == model.ValScalar && e.RHS.Type() == model.ValScalar {
 		return model.ValScalar
@@ -197,7 +196,7 @@ func (*StringLiteral) expr()  {}
 func (*UnaryExpr) expr()      {}
 func (*VectorSelector) expr() {}
 
-// VectorMatchCardinaly describes the cardinality relationship
+// VectorMatchCardinality describes the cardinality relationship
 // of two vectors in a binary operation.
 type VectorMatchCardinality int
 
@@ -235,9 +234,10 @@ type VectorMatching struct {
 	Include model.LabelNames
 }
 
-// A Visitor's Visit method is invoked for each node encountered by Walk.
+// Visitor allows visiting a Node and its child nodes. The Visit method is
-// If the result visitor w is not nil, Walk visits each of the children
+// invoked for each node encountered by Walk. If the result visitor w is not
-// of node with the visitor w, followed by a call of w.Visit(nil).
+// nil, Walk visits each of the children of node with the visitor w, followed
+// by a call of w.Visit(nil).
 type Visitor interface {
 	Visit(node Node) (w Visitor)
 }

promql/lex.go

@@ -225,11 +225,11 @@ func init() {
 	key["nan"] = itemNumber
 }
 
-func (t itemType) String() string {
+func (i itemType) String() string {
-	if s, ok := itemTypeStr[t]; ok {
+	if s, ok := itemTypeStr[i]; ok {
 		return s
 	}
-	return fmt.Sprintf("<item %d>", t)
+	return fmt.Sprintf("<item %d>", i)
 }
 
 func (i item) desc() string {
@@ -242,8 +242,8 @@ func (i item) desc() string {
 	return fmt.Sprintf("%s %s", i.typ.desc(), i)
 }
 
-func (t itemType) desc() string {
+func (i itemType) desc() string {
-	switch t {
+	switch i {
 	case itemError:
 		return "error"
 	case itemEOF:
@@ -261,7 +261,7 @@ func (t itemType) desc() string {
 	case itemDuration:
 		return "duration"
 	}
-	return fmt.Sprintf("%q", t)
+	return fmt.Sprintf("%q", i)
 }
 
 const eof = -1

promql/promql_test.go

@@ -24,7 +24,7 @@ func TestEvaluations(t *testing.T) {
 		t.Fatal(err)
 	}
 	for _, fn := range files {
-		test, err := NewTestFromFile(t, fn)
+		test, err := newTestFromFile(t, fn)
 		if err != nil {
 			t.Errorf("error creating test for %s: %s", fn, err)
 		}

promql/test.go

@@ -68,7 +68,7 @@ func NewTest(t testutil.T, input string) (*Test, error) {
 	return test, err
 }
 
-func NewTestFromFile(t testutil.T, filename string) (*Test, error) {
+func newTestFromFile(t testutil.T, filename string) (*Test, error) {
 	content, err := ioutil.ReadFile(filename)
 	if err != nil {
 		return nil, err
@@ -477,6 +477,7 @@ func (t *Test) clear() {
 	t.queryEngine = NewEngine(t.storage, nil)
 }
 
+// Close closes resources associated with the Test.
 func (t *Test) Close() {
 	t.queryEngine.Stop()
 	t.closeStorage()

retrieval/discovery/consul.go

@@ -32,22 +32,22 @@ const (
 	consulWatchTimeout  = 30 * time.Second
 	consulRetryInterval = 15 * time.Second
 
-	// ConsuleAddressLabel is the name for the label containing a target's address.
+	// consulAddressLabel is the name for the label containing a target's address.
-	ConsulAddressLabel = model.MetaLabelPrefix + "consul_address"
+	consulAddressLabel = model.MetaLabelPrefix + "consul_address"
-	// ConsuleNodeLabel is the name for the label containing a target's node name.
+	// consulNodeLabel is the name for the label containing a target's node name.
-	ConsulNodeLabel = model.MetaLabelPrefix + "consul_node"
+	consulNodeLabel = model.MetaLabelPrefix + "consul_node"
-	// ConsulTagsLabel is the name of the label containing the tags assigned to the target.
+	// consulTagsLabel is the name of the label containing the tags assigned to the target.
-	ConsulTagsLabel = model.MetaLabelPrefix + "consul_tags"
+	consulTagsLabel = model.MetaLabelPrefix + "consul_tags"
-	// ConsulServiceLabel is the name of the label containing the service name.
+	// consulServiceLabel is the name of the label containing the service name.
-	ConsulServiceLabel = model.MetaLabelPrefix + "consul_service"
+	consulServiceLabel = model.MetaLabelPrefix + "consul_service"
-	// ConsulServiceAddressLabel is the name of the label containing the (optional) service address.
+	// consulServiceAddressLabel is the name of the label containing the (optional) service address.
-	ConsulServiceAddressLabel = model.MetaLabelPrefix + "consul_service_address"
+	consulServiceAddressLabel = model.MetaLabelPrefix + "consul_service_address"
-	// ConsulServicePortLabel is the name of the label containing the service port.
+	// consulServicePortLabel is the name of the label containing the service port.
-	ConsulServicePortLabel = model.MetaLabelPrefix + "consul_service_port"
+	consulServicePortLabel = model.MetaLabelPrefix + "consul_service_port"
-	// ConsulDCLabel is the name of the label containing the datacenter ID.
+	// consulDCLabel is the name of the label containing the datacenter ID.
-	ConsulDCLabel = model.MetaLabelPrefix + "consul_dc"
+	consulDCLabel = model.MetaLabelPrefix + "consul_dc"
-	// ConsulServiceIDLabel is the name of the label containing the service ID.
+	// consulServiceIDLabel is the name of the label containing the service ID.
-	ConsulServiceIDLabel = model.MetaLabelPrefix + "consul_service_id"
+	consulServiceIDLabel = model.MetaLabelPrefix + "consul_service_id"
 )
 
 // ConsulDiscovery retrieves target information from a Consul server
@@ -226,8 +226,8 @@ func (cd *ConsulDiscovery) watchServices(update chan<- *consulService, done <-ch
 				cd.services[name] = srv
 			}
 			srv.tgroup.Labels = model.LabelSet{
-				ConsulServiceLabel: model.LabelValue(name),
+				consulServiceLabel: model.LabelValue(name),
-				ConsulDCLabel:      model.LabelValue(cd.clientDatacenter),
+				consulDCLabel:      model.LabelValue(cd.clientDatacenter),
 			}
 			update <- srv
 		}
@@ -272,12 +272,12 @@ func (cd *ConsulDiscovery) watchService(srv *consulService, ch chan<- *config.Ta
 
 			srv.tgroup.Targets = append(srv.tgroup.Targets, model.LabelSet{
 				model.AddressLabel:        model.LabelValue(addr),
-				ConsulAddressLabel:        model.LabelValue(node.Address),
+				consulAddressLabel:        model.LabelValue(node.Address),
-				ConsulNodeLabel:           model.LabelValue(node.Node),
+				consulNodeLabel:           model.LabelValue(node.Node),
-				ConsulTagsLabel:           model.LabelValue(tags),
+				consulTagsLabel:           model.LabelValue(tags),
-				ConsulServiceAddressLabel: model.LabelValue(node.ServiceAddress),
+				consulServiceAddressLabel: model.LabelValue(node.ServiceAddress),
-				ConsulServicePortLabel:    model.LabelValue(strconv.Itoa(node.ServicePort)),
+				consulServicePortLabel:    model.LabelValue(strconv.Itoa(node.ServicePort)),
-				ConsulServiceIDLabel:      model.LabelValue(node.ServiceID),
+				consulServiceIDLabel:      model.LabelValue(node.ServiceID),
 			})
 		}
 

retrieval/discovery/dns.go

@@ -31,7 +31,7 @@ import (
 const (
 	resolvConf = "/etc/resolv.conf"
 
-	DNSNameLabel = model.MetaLabelPrefix + "dns_name"
+	dnsNameLabel = model.MetaLabelPrefix + "dns_name"
 
 	// Constants for instrumentation.
 	namespace = "prometheus"
@@ -161,7 +161,7 @@ func (dd *DNSDiscovery) refresh(name string, ch chan<- *config.TargetGroup) erro
 		}
 		tg.Targets = append(tg.Targets, model.LabelSet{
 			model.AddressLabel: target,
-			DNSNameLabel:       model.LabelValue(name),
+			dnsNameLabel:       model.LabelValue(name),
 		})
 	}
 

retrieval/discovery/file.go

@@ -29,7 +29,7 @@ import (
 	"github.com/prometheus/prometheus/config"
 )
 
-const FileSDFilepathLabel = model.MetaLabelPrefix + "filepath"
+const fileSDFilepathLabel = model.MetaLabelPrefix + "filepath"
 
 // FileDiscovery provides service discovery functionality based
 // on files that contain target groups in JSON or YAML format. Refreshing
@@ -245,7 +245,7 @@ func readFile(filename string) ([]*config.TargetGroup, error) {
 		if tg.Labels == nil {
 			tg.Labels = model.LabelSet{}
 		}
-		tg.Labels[FileSDFilepathLabel] = model.LabelValue(filename)
+		tg.Labels[fileSDFilepathLabel] = model.LabelValue(filename)
 	}
 	return targetGroups, nil
 }

retrieval/discovery/kubernetes.go

@@ -18,8 +18,9 @@ import (
 	"github.com/prometheus/prometheus/retrieval/discovery/kubernetes"
 )
 
-func NewKubernetesDiscovery(conf *config.KubernetesSDConfig) (*kubernetes.KubernetesDiscovery, error) {
+// NewKubernetesDiscovery creates a Kubernetes service discovery based on the passed-in configuration.
-	kd := &kubernetes.KubernetesDiscovery{
+func NewKubernetesDiscovery(conf *config.KubernetesSDConfig) (*kubernetes.Discovery, error) {
+	kd := &kubernetes.Discovery{
 		Conf: conf,
 	}
 	err := kd.Initialize()

retrieval/discovery/kubernetes/discovery.go

@@ -65,8 +65,8 @@ const (
 	serviceEndpointsURL = apiPrefix + "/namespaces/%s/endpoints/%s"
 )
 
-// KubernetesDiscovery implements a TargetProvider for Kubernetes services.
+// Discovery implements a TargetProvider for Kubernetes services.
-type KubernetesDiscovery struct {
+type Discovery struct {
 	client *http.Client
 	Conf   *config.KubernetesSDConfig
 
@@ -81,7 +81,7 @@ type KubernetesDiscovery struct {
 }
 
 // Initialize sets up the discovery for usage.
-func (kd *KubernetesDiscovery) Initialize() error {
+func (kd *Discovery) Initialize() error {
 	client, err := newKubernetesHTTPClient(kd.Conf)
 
 	if err != nil {
@@ -97,7 +97,7 @@ func (kd *KubernetesDiscovery) Initialize() error {
 }
 
 // Sources implements the TargetProvider interface.
-func (kd *KubernetesDiscovery) Sources() []string {
+func (kd *Discovery) Sources() []string {
 	res, err := kd.client.Get(kd.Conf.Server + nodesURL)
 	if err != nil {
 		// If we can't list nodes then we can't watch them. Assume this is a misconfiguration
@@ -163,7 +163,7 @@ func (kd *KubernetesDiscovery) Sources() []string {
 }
 
 // Run implements the TargetProvider interface.
-func (kd *KubernetesDiscovery) Run(ch chan<- *config.TargetGroup, done <-chan struct{}) {
+func (kd *Discovery) Run(ch chan<- *config.TargetGroup, done <-chan struct{}) {
 	defer close(ch)
 
 	select {
@@ -215,7 +215,7 @@ func (kd *KubernetesDiscovery) Run(ch chan<- *config.TargetGroup, done <-chan st
 	}
 }
 
-func (kd *KubernetesDiscovery) updateNodesTargetGroup() *config.TargetGroup {
+func (kd *Discovery) updateNodesTargetGroup() *config.TargetGroup {
 	kd.nodesMu.Lock()
 	defer kd.nodesMu.Unlock()
 
@@ -239,7 +239,7 @@ func (kd *KubernetesDiscovery) updateNodesTargetGroup() *config.TargetGroup {
 	return tg
 }
 
-func (kd *KubernetesDiscovery) updateNode(node *Node, eventType EventType) {
+func (kd *Discovery) updateNode(node *Node, eventType EventType) {
 	kd.nodesMu.Lock()
 	defer kd.nodesMu.Unlock()
 	updatedNodeName := node.ObjectMeta.Name
@@ -254,7 +254,7 @@ func (kd *KubernetesDiscovery) updateNode(node *Node, eventType EventType) {
 }
 
 // watchNodes watches nodes as they come & go.
-func (kd *KubernetesDiscovery) watchNodes(events chan interface{}, done <-chan struct{}, retryInterval time.Duration) {
+func (kd *Discovery) watchNodes(events chan interface{}, done <-chan struct{}, retryInterval time.Duration) {
 	until(func() {
 		req, err := http.NewRequest("GET", kd.Conf.Server+nodesURL, nil)
 		if err != nil {
@@ -294,7 +294,7 @@ func (kd *KubernetesDiscovery) watchNodes(events chan interface{}, done <-chan s
 }
 
 // watchServices watches services as they come & go.
-func (kd *KubernetesDiscovery) watchServices(events chan interface{}, done <-chan struct{}, retryInterval time.Duration) {
+func (kd *Discovery) watchServices(events chan interface{}, done <-chan struct{}, retryInterval time.Duration) {
 	until(func() {
 		req, err := http.NewRequest("GET", kd.Conf.Server+servicesURL, nil)
 		if err != nil {
@@ -334,7 +334,7 @@ func (kd *KubernetesDiscovery) watchServices(events chan interface{}, done <-cha
 	}, retryInterval, done)
 }
 
-func (kd *KubernetesDiscovery) updateService(service *Service, eventType EventType) *config.TargetGroup {
+func (kd *Discovery) updateService(service *Service, eventType EventType) *config.TargetGroup {
 	kd.servicesMu.Lock()
 	defer kd.servicesMu.Unlock()
 
@@ -355,7 +355,7 @@ func (kd *KubernetesDiscovery) updateService(service *Service, eventType EventTy
 	return nil
 }
 
-func (kd *KubernetesDiscovery) deleteService(service *Service) *config.TargetGroup {
+func (kd *Discovery) deleteService(service *Service) *config.TargetGroup {
 	tg := &config.TargetGroup{Source: serviceSource(service)}
 
 	delete(kd.services[service.ObjectMeta.Namespace], service.ObjectMeta.Name)
@@ -366,7 +366,7 @@ func (kd *KubernetesDiscovery) deleteService(service *Service) *config.TargetGro
 	return tg
 }
 
-func (kd *KubernetesDiscovery) addService(service *Service) *config.TargetGroup {
+func (kd *Discovery) addService(service *Service) *config.TargetGroup {
 	namespace, ok := kd.services[service.ObjectMeta.Namespace]
 	if !ok {
 		namespace = map[string]*Service{}
@@ -386,16 +386,16 @@ func (kd *KubernetesDiscovery) addService(service *Service) *config.TargetGroup
 		return nil
 	}
 
-	var endpoints Endpoints
+	var eps Endpoints
-	if err := json.NewDecoder(res.Body).Decode(&endpoints); err != nil {
+	if err := json.NewDecoder(res.Body).Decode(&eps); err != nil {
 		log.Errorf("Error getting service endpoints: %s", err)
 		return nil
 	}
 
-	return kd.updateServiceTargetGroup(service, &endpoints)
+	return kd.updateServiceTargetGroup(service, &eps)
 }
 
-func (kd *KubernetesDiscovery) updateServiceTargetGroup(service *Service, endpoints *Endpoints) *config.TargetGroup {
+func (kd *Discovery) updateServiceTargetGroup(service *Service, eps *Endpoints) *config.TargetGroup {
 	tg := &config.TargetGroup{
 		Source: serviceSource(service),
 		Labels: model.LabelSet{
@@ -415,10 +415,10 @@ func (kd *KubernetesDiscovery) updateServiceTargetGroup(service *Service, endpoi
 	}
 
 	// Now let's loop through the endpoints & add them to the target group with appropriate labels.
-	for _, eps := range endpoints.Subsets {
+	for _, ss := range eps.Subsets {
-		epPort := eps.Ports[0].Port
+		epPort := ss.Ports[0].Port
 
-		for _, addr := range eps.Addresses {
+		for _, addr := range ss.Addresses {
 			ipAddr := addr.IP
 			if len(ipAddr) == net.IPv6len {
 				ipAddr = "[" + ipAddr + "]"
@@ -435,7 +435,7 @@ func (kd *KubernetesDiscovery) updateServiceTargetGroup(service *Service, endpoi
 }
 
 // watchServiceEndpoints watches service endpoints as they come & go.
-func (kd *KubernetesDiscovery) watchServiceEndpoints(events chan interface{}, done <-chan struct{}, retryInterval time.Duration) {
+func (kd *Discovery) watchServiceEndpoints(events chan interface{}, done <-chan struct{}, retryInterval time.Duration) {
 	until(func() {
 		req, err := http.NewRequest("GET", kd.Conf.Server+endpointsURL, nil)
 		if err != nil {
@@ -475,7 +475,7 @@ func (kd *KubernetesDiscovery) watchServiceEndpoints(events chan interface{}, do
 	}, retryInterval, done)
 }
 
-func (kd *KubernetesDiscovery) updateServiceEndpoints(endpoints *Endpoints, eventType EventType) *config.TargetGroup {
+func (kd *Discovery) updateServiceEndpoints(endpoints *Endpoints, eventType EventType) *config.TargetGroup {
 	kd.servicesMu.Lock()
 	defer kd.servicesMu.Unlock()
 

retrieval/discovery/serverset.go

@@ -49,11 +49,11 @@ type serversetEndpoint struct {
 	Port int
 }
 
-type ZookeeperLogger struct {
+type zookeeperLogger struct {
 }
 
 // Implements zk.Logger
-func (zl ZookeeperLogger) Printf(s string, i ...interface{}) {
+func (zl zookeeperLogger) Printf(s string, i ...interface{}) {
 	log.Infof(s, i...)
 }
 
@@ -72,7 +72,7 @@ type ServersetDiscovery struct {
 // NewServersetDiscovery returns a new ServersetDiscovery for the given config.
 func NewServersetDiscovery(conf *config.ServersetSDConfig) *ServersetDiscovery {
 	conn, _, err := zk.Connect(conf.Servers, time.Duration(conf.Timeout))
-	conn.SetLogger(ZookeeperLogger{})
+	conn.SetLogger(zookeeperLogger{})
 	if err != nil {
 		return nil
 	}
@@ -84,7 +84,7 @@ func NewServersetDiscovery(conf *config.ServersetSDConfig) *ServersetDiscovery {
 		sources: map[string]*config.TargetGroup{},
 	}
 	go sd.processUpdates()
-	sd.treeCache = NewZookeeperTreeCache(conn, conf.Paths[0], updates)
+	sd.treeCache = newZookeeperTreeCache(conn, conf.Paths[0], updates)
 	return sd
 }
 
@@ -194,7 +194,7 @@ type zookeeperTreeCacheNode struct {
 	children map[string]*zookeeperTreeCacheNode
 }
 
-func NewZookeeperTreeCache(conn *zk.Conn, path string, events chan zookeeperTreeCacheEvent) *zookeeperTreeCache {
+func newZookeeperTreeCache(conn *zk.Conn, path string, events chan zookeeperTreeCacheEvent) *zookeeperTreeCache {
 	tc := &zookeeperTreeCache{
 		conn:   conn,
 		prefix: path,

retrieval/target.go

@@ -90,11 +90,11 @@ func (t TargetHealth) value() model.SampleValue {
 }
 
 const (
-	// Unknown is the state of a Target before it is first scraped.
+	// HealthUnknown is the state of a Target before it is first scraped.
 	HealthUnknown TargetHealth = iota
-	// Healthy is the state of a Target that has been successfully scraped.
+	// HealthGood is the state of a Target that has been successfully scraped.
 	HealthGood
-	// Unhealthy is the state of a Target that was scraped unsuccessfully.
+	// HealthBad is the state of a Target that was scraped unsuccessfully.
 	HealthBad
 )
 
@@ -258,7 +258,7 @@ func newHTTPClient(cfg *config.ScrapeConfig) (*http.Client, error) {
 		// Load CA cert.
 		caCert, err := ioutil.ReadFile(cfg.CACert)
 		if err != nil {
-			return nil, fmt.Errorf("Unable to use specified CA cert %s: %s", cfg.CACert, err)
+			return nil, fmt.Errorf("unable to use specified CA cert %s: %s", cfg.CACert, err)
 		}
 		caCertPool.AppendCertsFromPEM(caCert)
 		tlsConfig.RootCAs = caCertPool
@@ -268,7 +268,7 @@ func newHTTPClient(cfg *config.ScrapeConfig) (*http.Client, error) {
 	if cfg.ClientCert != nil && len(cfg.ClientCert.Cert) > 0 && len(cfg.ClientCert.Key) > 0 {
 		cert, err := tls.LoadX509KeyPair(cfg.ClientCert.Cert, cfg.ClientCert.Key)
 		if err != nil {
-			return nil, fmt.Errorf("Unable to use specified client cert (%s) & key (%s): %s", cfg.ClientCert.Cert, cfg.ClientCert.Key, err)
+			return nil, fmt.Errorf("unable to use specified client cert (%s) & key (%s): %s", cfg.ClientCert.Cert, cfg.ClientCert.Key, err)
 		}
 		tlsConfig.Certificates = []tls.Certificate{cert}
 	}
@@ -285,12 +285,13 @@ func newHTTPClient(cfg *config.ScrapeConfig) (*http.Client, error) {
 	// Authorization header correctly on each request.
 	bearerToken := cfg.BearerToken
 	if len(bearerToken) == 0 && len(cfg.BearerTokenFile) > 0 {
-		if b, err := ioutil.ReadFile(cfg.BearerTokenFile); err != nil {
+		b, err := ioutil.ReadFile(cfg.BearerTokenFile)
-			return nil, fmt.Errorf("Unable to read bearer token file %s: %s", cfg.BearerTokenFile, err)
+		if err != nil {
-		} else {
+			return nil, fmt.Errorf("unable to read bearer token file %s: %s", cfg.BearerTokenFile, err)
+		}
 		bearerToken = string(b)
 	}
-	}
+
 	if len(bearerToken) > 0 {
 		rt = httputil.NewBearerAuthRoundTripper(bearerToken, rt)
 	}

retrieval/targetmanager.go

@@ -550,7 +550,7 @@ func (sd *StaticProvider) Run(ch chan<- *config.TargetGroup, done <-chan struct{
 	<-done
 }
 
-// TargetGroups returns the provider's target groups.
+// Sources returns the provider's sources.
 func (sd *StaticProvider) Sources() (srcs []string) {
 	for _, tg := range sd.TargetGroups {
 		srcs = append(srcs, tg.Source)

rules/alerting.go

@@ -52,13 +52,13 @@ func (s AlertState) String() string {
 }
 
 const (
-	// Inactive alerts are neither firing nor pending.
+	// StateInactive is the state of an alert that is either firing nor pending.
 	StateInactive AlertState = iota
-	// Pending alerts have been active for less than the configured
+	// StatePending is the state of an alert that has been active for less than
-	// threshold duration.
+	// the configured threshold duration.
 	StatePending
-	// Firing alerts have been active for longer than the configured
+	// StateFiring is the state of an alert that has been active for longer than
-	// threshold duration.
+	// the configured threshold duration.
 	StateFiring
 )
 

rules/manager.go

@@ -269,7 +269,7 @@ func (m *Manager) runIteration() {
 					float64(duration / time.Millisecond),
 				)
 			default:
-				panic(fmt.Errorf("Unknown rule type: %T", rule))
+				panic(fmt.Errorf("unknown rule type: %T", rule))
 			}
 
 			for _, s := range vector {

storage/local/series.go

@@ -638,16 +638,16 @@ func (it *memorySeriesIterator) chunkIterator(i int) chunkIterator {
 type nopSeriesIterator struct{}
 
 // ValueAtTime implements SeriesIterator.
-func (_ nopSeriesIterator) ValueAtTime(t model.Time) []model.SamplePair {
+func (i nopSeriesIterator) ValueAtTime(t model.Time) []model.SamplePair {
 	return []model.SamplePair{}
 }
 
 // BoundaryValues implements SeriesIterator.
-func (_ nopSeriesIterator) BoundaryValues(in metric.Interval) []model.SamplePair {
+func (i nopSeriesIterator) BoundaryValues(in metric.Interval) []model.SamplePair {
 	return []model.SamplePair{}
 }
 
 // RangeValues implements SeriesIterator.
-func (_ nopSeriesIterator) RangeValues(in metric.Interval) []model.SamplePair {
+func (i nopSeriesIterator) RangeValues(in metric.Interval) []model.SamplePair {
 	return []model.SamplePair{}
 }

template/template.go

@@ -101,7 +101,8 @@ func query(q string, timestamp model.Time, queryEngine *promql.Engine) (queryRes
 	return result, nil
 }
 
-type templateExpander struct {
+// Expander executes templates in text or HTML mode with a common set of Prometheus template functions.
+type Expander struct {
 	text    string
 	name    string
 	data    interface{}
@@ -109,8 +110,8 @@ type templateExpander struct {
 }
 
 // NewTemplateExpander returns a template expander ready to use.
-func NewTemplateExpander(text string, name string, data interface{}, timestamp model.Time, queryEngine *promql.Engine, pathPrefix string) *templateExpander {
+func NewTemplateExpander(text string, name string, data interface{}, timestamp model.Time, queryEngine *promql.Engine, pathPrefix string) *Expander {
-	return &templateExpander{
+	return &Expander{
 		text: text,
 		name: name,
 		data: data,
@@ -249,16 +250,16 @@ func NewTemplateExpander(text string, name string, data interface{}, timestamp m
 	}
 }
 
-// Funcs adds the functions in fm to the templateExpander's function map.
+// Funcs adds the functions in fm to the Expander's function map.
 // Existing functions will be overwritten in case of conflict.
-func (te templateExpander) Funcs(fm text_template.FuncMap) {
+func (te Expander) Funcs(fm text_template.FuncMap) {
 	for k, v := range fm {
 		te.funcMap[k] = v
 	}
 }
 
-// Expand a template.
+// Expand expands a template in text (non-HTML) mode.
-func (te templateExpander) Expand() (result string, resultErr error) {
+func (te Expander) Expand() (result string, resultErr error) {
 	// It'd better to have no alert description than to kill the whole process
 	// if there's a bug in the template.
 	defer func() {
@@ -283,8 +284,8 @@ func (te templateExpander) Expand() (result string, resultErr error) {
 	return buffer.String(), nil
 }
 
-// Expand a template with HTML escaping, with templates read from the given files.
+// ExpandHTML expands a template with HTML escaping, with templates read from the given files.
-func (te templateExpander) ExpandHTML(templateFiles []string) (result string, resultErr error) {
+func (te Expander) ExpandHTML(templateFiles []string) (result string, resultErr error) {
 	defer func() {
 		if r := recover(); r != nil {
 			var ok bool

util/testutil/directory.go

@@ -77,7 +77,7 @@ func (c callbackCloser) Close() {
 
 // NewCallbackCloser returns a Closer that calls the provided function upon
 // closing.
-func NewCallbackCloser(fn func()) *callbackCloser {
+func NewCallbackCloser(fn func()) Closer {
 	return &callbackCloser{
 		fn: fn,
 	}

web/api/legacy/api.go

@@ -32,7 +32,7 @@ type API struct {
 	QueryEngine *promql.Engine
 }
 
-// RegisterHandler registers the handler for the various endpoints below /api.
+// Register registers the handler for the various endpoints below /api.
 func (api *API) Register(router *route.Router) {
 	router.Get("/query", handle("query", api.Query))
 	router.Get("/query_range", handle("query_range", api.QueryRange))

web/api/legacy/query.go

@@ -225,7 +225,7 @@ func (api *API) Metrics(w http.ResponseWriter, r *http.Request) {
 	resultBytes, err := json.Marshal(metricNames)
 	if err != nil {
 		log.Error("Error marshalling metric names: ", err)
-		httpJSONError(w, fmt.Errorf("Error marshalling metric names: %s", err), http.StatusInternalServerError)
+		httpJSONError(w, fmt.Errorf("error marshalling metric names: %s", err), http.StatusInternalServerError)
 		return
 	}
 	w.Write(resultBytes)

web/federate.go

@@ -27,6 +27,7 @@ import (
 	"github.com/prometheus/common/model"
 )
 
+// Federation implements a web handler to serve scrape federation requests.
 type Federation struct {
 	Storage local.Storage
 }

web/web.go

@@ -337,11 +337,11 @@ func (h *Handler) consolesPath() string {
 func (h *Handler) getTemplate(name string) (string, error) {
 	baseTmpl, err := h.getTemplateFile("_base")
 	if err != nil {
-		return "", fmt.Errorf("Error reading base template: %s", err)
+		return "", fmt.Errorf("error reading base template: %s", err)
 	}
 	pageTmpl, err := h.getTemplateFile(name)
 	if err != nil {
-		return "", fmt.Errorf("Error reading page template %s: %s", name, err)
+		return "", fmt.Errorf("error reading page template %s: %s", name, err)
 	}
 	return baseTmpl + pageTmpl, nil
 }