Fix various golangci-lint nags

Add a minimal .golangci.yml config and address the most obvious lint
warnings.

Signed-off-by: Daniel Swarbrick <[email protected]>

.golangci.yml

@@ -0,0 +1,18 @@
+linters:
+  enable:
+    - errorlint
+    - goimports
+    - misspell
+    - perfsprint
+    - testifylint
+    - usestdlibvars
+
+issues:
+  exclude-rules:
+    - path: _test.go
+      linters:
+        - errcheck
+
+linters-settings:
+  goimports:
+    local-prefixes: github.com/boynux/squid-exporter

collector/client.go

@@ -15,7 +15,7 @@ import (
 	"github.com/boynux/squid-exporter/types"
 )
 
-/*CacheObjectClient holds information about squid manager */
+// CacheObjectClient holds information about Squid manager.
 type CacheObjectClient struct {
 	ch              connectionHandler
 	basicAuthString string
@@ -31,7 +31,7 @@ type connectionHandlerImpl struct {
 	port     int
 }
 
-/*SquidClient provides functionality to fetch squid metrics */
+// SquidClient provides functionality to fetch Squid metrics.
 type SquidClient interface {
 	GetCounters() (types.Counters, error)
 	GetServiceTimes() (types.Counters, error)
@@ -45,9 +45,9 @@ const (
 func buildBasicAuthString(login string, password string) string {
 	if len(login) == 0 {
 		return ""
-	} else {
-		return base64.StdEncoding.EncodeToString([]byte(login + ":" + password))
 	}
+
+	return base64.StdEncoding.EncodeToString([]byte(login + ":" + password))
 }
 
 type CacheObjectRequest struct {
@@ -58,7 +58,7 @@ type CacheObjectRequest struct {
 	Headers  []string
 }
 
-/*NewCacheObjectClient initializes a new cache client */
+// NewCacheObjectClient initializes a new cache client.
 func NewCacheObjectClient(cor *CacheObjectRequest) *CacheObjectClient {
 	return &CacheObjectClient{
 		&connectionHandlerImpl{
@@ -82,8 +82,8 @@ func (c *CacheObjectClient) readFromSquid(endpoint string) (*bufio.Reader, error
 		return nil, err
 	}
 
-	if r.StatusCode != 200 {
-		return nil, fmt.Errorf("Non success code %d while fetching metrics", r.StatusCode)
+	if r.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("non-success code %d while fetching metrics", r.StatusCode)
 	}
 
 	return bufio.NewReader(r.Body), err
@@ -106,13 +106,13 @@ func readLines(reader *bufio.Reader, lines chan<- string) {
 	close(lines)
 }
 
-/*GetCounters fetches counters from squid cache manager */
+// GetCounters fetches counters from Squid cache manager.
 func (c *CacheObjectClient) GetCounters() (types.Counters, error) {
 	var counters types.Counters
 
 	reader, err := c.readFromSquid("counters")
 	if err != nil {
-		return nil, fmt.Errorf("error getting counters: %v", err)
+		return nil, fmt.Errorf("error getting counters: %w", err)
 	}
 
 	lines := make(chan string)
@@ -130,39 +130,36 @@ func (c *CacheObjectClient) GetCounters() (types.Counters, error) {
 	return counters, err
 }
 
-/*GetServiceTimes fetches service times from squid cache manager */
+// GetServiceTimes fetches service times from Squid cache manager.
 func (c *CacheObjectClient) GetServiceTimes() (types.Counters, error) {
 	var serviceTimes types.Counters
 
 	reader, err := c.readFromSquid("service_times")
 	if err != nil {
-		return nil, fmt.Errorf("error getting service times: %v", err)
+		return nil, fmt.Errorf("error getting service times: %w", err)
 	}
 
 	lines := make(chan string)
 	go readLines(reader, lines)
 
 	for line := range lines {
-		s, err := decodeServiceTimeStrings(line)
-		if err != nil {
+		if s, err := decodeServiceTimeStrings(line); err != nil {
 			log.Println(err)
-		} else {
-			if s.Key != "" {
-				serviceTimes = append(serviceTimes, s)
-			}
+		} else if s.Key != "" {
+			serviceTimes = append(serviceTimes, s)
 		}
 	}
 
 	return serviceTimes, err
 }
 
-/*GetInfos fetches info from squid cache manager */
+// GetInfos fetches info from Squid cache manager.
 func (c *CacheObjectClient) GetInfos() (types.Counters, error) {
 	var infos types.Counters
 
 	reader, err := c.readFromSquid("info")
 	if err != nil {
-		return nil, fmt.Errorf("error getting info: %v", err)
+		return nil, fmt.Errorf("error getting info: %w", err)
 	}
 
 	lines := make(chan string)
@@ -193,7 +190,6 @@ func (c *CacheObjectClient) GetInfos() (types.Counters, error) {
 						infoAvg60.Value = value
 						infos = append(infos, infoAvg60)
 					}
-
 				} else {
 					infoVarLabels.VarLabels = append(infoVarLabels.VarLabels, dis.VarLabels[0])
 				}
@@ -303,7 +299,7 @@ func decodeInfoStrings(line string) (types.Counter, error) {
 			// metrics with value as string need to save as label, format like "Squid Object Cache: Version 6.1" (the 3 first metrics)
 			if key == "Squid_Object_Cache" || key == "Build_Info" || key == "Service_Name" {
 				if key == "Squid_Object_Cache" { // To clarify that the value is the squid version.
-					key = key + "_Version"
+					key += "_Version"
 					if slices := strings.Split(value, " "); len(slices) > 0 {
 						value = slices[1]
 					}
@@ -344,10 +340,9 @@ func decodeInfoStrings(line string) (types.Counter, error) {
 					infoAvgCounter.VarLabels = append(infoAvgCounter.VarLabels, infoAvg5mVarLabel, infoAvg60mVarLabel)
 
 					return infoAvgCounter, nil
-				} else {
-					value = slices[0]
 				}
 
+				value = slices[0]
 			}
 
 			value = strings.Replace(value, "%", "", -1)
@@ -359,7 +354,7 @@ func decodeInfoStrings(line string) (types.Counter, error) {
 		}
 	} else {
 		// this catch the last 4 metrics format like "value metricName"
-		lineTrimed := strings.TrimSpace(line[:])
+		lineTrimed := strings.TrimSpace(line)
 
 		if idx := strings.Index(lineTrimed, " "); idx >= 0 {
 			key := strings.TrimSpace(lineTrimed[idx+1:])

collector/client_test.go

@@ -4,8 +4,10 @@ import (
 	"net"
 	"testing"
 
-	"github.com/boynux/squid-exporter/types"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/boynux/squid-exporter/types"
 )
 
 type mockConnectionHandler struct {
@@ -74,7 +76,7 @@ func TestDecodeMetricStrings(t *testing.T) {
 		c, err := tc.d(tc.s)
 
 		if tc.e != "" {
-			assert.EqualError(t, err, tc.e)
+			require.EqualError(t, err, tc.e)
 		}
 		assert.Equal(t, tc.c, c)
 	}

collector/metrics.go

@@ -4,8 +4,9 @@ import (
 	"log"
 	"time"
 
-	"github.com/boynux/squid-exporter/config"
 	"github.com/prometheus/client_golang/prometheus"
+
+	"github.com/boynux/squid-exporter/config"
 )
 
 type descMap map[string]*prometheus.Desc
@@ -22,7 +23,7 @@ var (
 	infos               descMap
 )
 
-/*Exporter entry point to squid exporter */
+// Exporter entry point to Squid exporter.
 type Exporter struct {
 	client SquidClient
 
@@ -42,7 +43,7 @@ type CollectorConfig struct {
 	Headers  []string
 }
 
-/*New initializes a new exporter */
+// New initializes a new exporter.
 func New(c *CollectorConfig) *Exporter {
 	counters = generateSquidCounters(c.Labels.Keys)
 	if ExtractServiceTimes {
@@ -90,10 +91,9 @@ func (e *Exporter) Describe(ch chan<- *prometheus.Desc) {
 	for _, v := range infos {
 		ch <- v
 	}
-
 }
 
-/*Collect fetches metrics from squid manager and pushes them to promethus */
+// Collect fetches metrics from Squid manager and expose them to Prometheus.
 func (e *Exporter) Collect(c chan<- prometheus.Metric) {
 	insts, err := e.client.GetCounters()
 

collector/service_times.go

@@ -119,8 +119,7 @@ func generateSquidServiceTimes(labels []string) descMap {
 	for i := range squidServiceTimess {
 		serviceTime := squidServiceTimess[i]
 
-		var key string
-		var name string
+		var key, name string
 
 		if serviceTime.Counter != "" {
 			key = fmt.Sprintf("%s_%s_%s", serviceTime.Section, serviceTime.Counter, serviceTime.Suffix)
@@ -129,7 +128,7 @@ func generateSquidServiceTimes(labels []string) descMap {
 		} else {
 			key = fmt.Sprintf("%s_%s", serviceTime.Section, serviceTime.Suffix)
 			name = prometheus.BuildFQName(namespace, strings.Replace(serviceTime.Section, ".", "_", -1),
-				fmt.Sprintf("%s", serviceTime.Suffix))
+				serviceTime.Suffix)
 		}
 
 		serviceTimes[key] = prometheus.NewDesc(

config/config.go

@@ -1,6 +1,7 @@
 package config
 
 import (
+	"errors"
 	"flag"
 	"fmt"
 	"log"
@@ -42,7 +43,7 @@ type Labels struct {
 	Values []string
 }
 
-/*Config configurations for exporter */
+// Config configurations for exporter.
 type Config struct {
 	ListenAddress       string
 	WebConfigPath       string
@@ -59,7 +60,7 @@ type Config struct {
 	UseProxyHeader bool
 }
 
-/*NewConfig creates a new config object from command line args */
+// NewConfig creates a new config object from command line args.
 func NewConfig() *Config {
 	c := &Config{}
 
@@ -146,12 +147,12 @@ func (l *Labels) Set(value string) error {
 	args := strings.Split(value, "=")
 
 	if len(args) != 2 || len(args[1]) < 1 {
-		return fmt.Errorf("Label must be in 'key=value' format")
+		return errors.New("label must be in 'key=value' format")
 	}
 
 	for _, key := range l.Keys {
 		if key == args[0] {
-			return fmt.Errorf("Labels must be distinct, found duplicated key %s", args[0])
+			return fmt.Errorf("labels must be distinct; found duplicate key %q", args[0])
 		}
 	}
 	l.Keys = append(l.Keys, args[0])

helpers.go

@@ -6,9 +6,9 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/boynux/squid-exporter/config"
-
 	proxyproto "github.com/pires/go-proxyproto"
+
+	"github.com/boynux/squid-exporter/config"
 )
 
 func createProxyHeader(cfg *config.Config) string {

main.go

@@ -8,15 +8,16 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/boynux/squid-exporter/collector"
-	"github.com/boynux/squid-exporter/config"
 	kitlog "github.com/go-kit/log"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/collectors"
 	versioncollector "github.com/prometheus/client_golang/prometheus/collectors/version"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/prometheus/common/version"
 	"github.com/prometheus/exporter-toolkit/web"
+
+	"github.com/boynux/squid-exporter/collector"
+	"github.com/boynux/squid-exporter/config"
 )
 
 func init() {
@@ -53,11 +54,11 @@ func main() {
 			PidFn: func() (int, error) {
 				content, err := os.ReadFile(cfg.Pidfile)
 				if err != nil {
-					return 0, fmt.Errorf("can't read pid file %q: %s", cfg.Pidfile, err)
+					return 0, fmt.Errorf("cannot read pid file %q: %w", cfg.Pidfile, err)
 				}
 				value, err := strconv.Atoi(strings.TrimSpace(string(content)))
 				if err != nil {
-					return 0, fmt.Errorf("can't parse pid file %q: %s", cfg.Pidfile, err)
+					return 0, fmt.Errorf("cannot parse pid file %q: %w", cfg.Pidfile, err)
 				}
 				return value, nil
 			},

types/types.go

@@ -1,17 +1,17 @@
 package types
 
-/*VarLabel maps key value prometheus labes*/
+// VarLabel maps key value Prometheus labels.
 type VarLabel struct {
 	Key   string
 	Value string
 }
 
-/*Counter maps a squid conters */
+// Counter maps a Squid counter.
 type Counter struct {
 	Key       string
 	Value     float64
 	VarLabels []VarLabel
 }
 
-/*Counters is a list of multiple squid counters */
+// Counters is a list of multiple Squid counters.
 type Counters []Counter