Remove unused *prometheus.Desc return value from collectors `collec…

…t()` function (#1475)

.golangci.yaml

@@ -1,14 +1,16 @@
 linters:
   disable-all: true
   enable:
-  - deadcode
   - errcheck
   - revive
   - govet
   - gofmt
   - ineffassign
   - unconvert
-  - varcheck
+  - nilnil
+  - nilerr
+  - unparam
+  - loggercheck
 
 issues:
   exclude:

exporter.go

@@ -184,7 +184,7 @@ func main() {
 		w.Header().Set("Content-Type", "application/json")
 		_, err := fmt.Fprintln(w, `{"status":"ok"}`)
 		if err != nil {
-			_ = level.Debug(logger).Log("Failed to write to stream", "err", err)
+			_ = level.Debug(logger).Log("msg", "Failed to write to stream", "err", err)
 		}
 	})
 	mux.HandleFunc("/version", func(w http.ResponseWriter, r *http.Request) {

pkg/collector/ad/ad.go

@@ -490,8 +490,8 @@ func (c *collector) Build() error {
 // Collect sends the metric values for each metric
 // to the provided prometheus Metric channel.
 func (c *collector) Collect(_ *types.ScrapeContext, ch chan<- prometheus.Metric) error {
-	if desc, err := c.collect(ch); err != nil {
-		_ = level.Error(c.logger).Log("msg", "failed collecting ad metrics", "desc", desc, "err", err)
+	if err := c.collect(ch); err != nil {
+		_ = level.Error(c.logger).Log("msg", "failed collecting ad metrics", "err", err)
 		return err
 	}
 	return nil
@@ -649,14 +649,14 @@ type Win32_PerfRawData_DirectoryServices_DirectoryServices struct {
 	TransitivesuboperationsPersec                                    uint32
 }
 
-func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, error) {
+func (c *collector) collect(ch chan<- prometheus.Metric) error {
 	var dst []Win32_PerfRawData_DirectoryServices_DirectoryServices
 	q := wmi.QueryAll(&dst, c.logger)
 	if err := wmi.Query(q, &dst); err != nil {
-		return nil, err
+		return err
 	}
 	if len(dst) == 0 {
-		return nil, errors.New("WMI query returned empty result set")
+		return errors.New("WMI query returned empty result set")
 	}
 
 	ch <- prometheus.MustNewConstMetric(
@@ -1350,5 +1350,5 @@ func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, erro
 		float64(dst[0].TombstonesVisitedPersec),
 	)
 
-	return nil, nil
+	return nil
 }

pkg/collector/adcs/adcs.go

@@ -145,8 +145,8 @@ func (c *collector) Build() error {
 }
 
 func (c *collector) Collect(ctx *types.ScrapeContext, ch chan<- prometheus.Metric) error {
-	if desc, err := c.collectADCSCounters(ctx, ch); err != nil {
-		_ = level.Error(c.logger).Log("msg", "failed collecting ADCS metrics", "desc", desc, "err", err)
+	if err := c.collectADCSCounters(ctx, ch); err != nil {
+		_ = level.Error(c.logger).Log("msg", "failed collecting ADCS metrics", "err", err)
 		return err
 	}
 	return nil
@@ -169,17 +169,17 @@ type perflibADCS struct {
 	SignedCertificateTimestampListProcessingTime float64 `perflib:"Signed Certificate Timestamp List processing time (ms)"`
 }
 
-func (c *collector) collectADCSCounters(ctx *types.ScrapeContext, ch chan<- prometheus.Metric) (*prometheus.Desc, error) {
+func (c *collector) collectADCSCounters(ctx *types.ScrapeContext, ch chan<- prometheus.Metric) error {
 	dst := make([]perflibADCS, 0)
 	if _, ok := ctx.PerfObjects["Certification Authority"]; !ok {
-		return nil, errors.New("perflib did not contain an entry for Certification Authority")
+		return errors.New("perflib did not contain an entry for Certification Authority")
 	}
 	err := perflib.UnmarshalObject(ctx.PerfObjects["Certification Authority"], &dst, c.logger)
 	if err != nil {
-		return nil, err
+		return err
 	}
 	if len(dst) == 0 {
-		return nil, errors.New("perflib query for Certification Authority (ADCS) returned empty result set")
+		return errors.New("perflib query for Certification Authority (ADCS) returned empty result set")
 	}
 
 	for _, d := range dst {
@@ -267,5 +267,5 @@ func (c *collector) collectADCSCounters(ctx *types.ScrapeContext, ch chan<- prom
 		)
 	}
 
-	return nil, nil
+	return nil
 }

pkg/collector/cache/cache.go

@@ -254,8 +254,8 @@ func (c *collector) Build() error {
 
 // Collect implements the Collector interface
 func (c *collector) Collect(ctx *types.ScrapeContext, ch chan<- prometheus.Metric) error {
-	if desc, err := c.collect(ctx, ch); err != nil {
-		_ = level.Error(c.logger).Log("msg", "failed collecting cache metrics", "desc", desc, "err", err)
+	if err := c.collect(ctx, ch); err != nil {
+		_ = level.Error(c.logger).Log("msg", "failed collecting cache metrics", "err", err)
 		return err
 	}
 	return nil
@@ -295,10 +295,10 @@ type perflibCache struct {
 	SyncPinReadsTotal           float64 `perflib:"Sync Pin Reads/sec"`
 }
 
-func (c *collector) collect(ctx *types.ScrapeContext, ch chan<- prometheus.Metric) (*prometheus.Desc, error) {
+func (c *collector) collect(ctx *types.ScrapeContext, ch chan<- prometheus.Metric) error {
 	var dst []perflibCache // Single-instance class, array is required but will have single entry.
 	if err := perflib.UnmarshalObject(ctx.PerfObjects["Cache"], &dst, c.logger); err != nil {
-		return nil, err
+		return err
 	}
 
 	ch <- prometheus.MustNewConstMetric(
@@ -475,5 +475,5 @@ func (c *collector) collect(ctx *types.ScrapeContext, ch chan<- prometheus.Metri
 		dst[0].SyncPinReadsTotal,
 	)
 
-	return nil, nil
+	return nil
 }

pkg/collector/container/container.go

@@ -193,8 +193,8 @@ func (c *collector) Build() error {
 // Collect sends the metric values for each metric
 // to the provided prometheus Metric channel.
 func (c *collector) Collect(_ *types.ScrapeContext, ch chan<- prometheus.Metric) error {
-	if desc, err := c.collect(ch); err != nil {
-		_ = level.Error(c.logger).Log("msg", "failed collecting collector metrics", "desc", desc, "err", err)
+	if err := c.collect(ch); err != nil {
+		_ = level.Error(c.logger).Log("msg", "failed collecting collector metrics", "err", err)
 		return err
 	}
 	return nil
@@ -208,12 +208,12 @@ func (c *collector) containerClose(container hcsshim.Container) {
 	}
 }
 
-func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, error) {
+func (c *collector) collect(ch chan<- prometheus.Metric) error {
 	// Types Container is passed to get the containers compute systems only
 	containers, err := hcsshim.GetContainers(hcsshim.ComputeSystemQuery{Types: []string{"Container"}})
 	if err != nil {
 		_ = level.Error(c.logger).Log("msg", "Err in Getting containers", "err", err)
-		return nil, err
+		return err
 	}
 
 	count := len(containers)
@@ -224,7 +224,7 @@ func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, erro
 		float64(count),
 	)
 	if count == 0 {
-		return nil, nil
+		return nil
 	}
 
 	containerPrefixes := make(map[string]string)
@@ -322,12 +322,12 @@ func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, erro
 	hnsEndpoints, err := hcsshim.HNSListEndpointRequest()
 	if err != nil {
 		_ = level.Warn(c.logger).Log("msg", "Failed to collect network stats for containers")
-		return nil, nil
+		return err
 	}
 
 	if len(hnsEndpoints) == 0 {
 		_ = level.Info(c.logger).Log("msg", fmt.Sprintf("No network stats for containers to collect"))
-		return nil, nil
+		return nil
 	}
 
 	for _, endpoint := range hnsEndpoints {
@@ -386,7 +386,7 @@ func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, erro
 		}
 	}
 
-	return nil, nil
+	return nil
 }
 
 func getContainerIdWithPrefix(containerDetails hcsshim.ContainerProperties) string {

pkg/collector/cpu_info/cpu_info.go

@@ -86,23 +86,23 @@ type win32_Processor struct {
 // Collect sends the metric values for each metric
 // to the provided prometheus Metric channel.
 func (c *collector) Collect(_ *types.ScrapeContext, ch chan<- prometheus.Metric) error {
-	if desc, err := c.collect(ch); err != nil {
-		_ = level.Error(c.logger).Log("msg", "failed collecting cpu_info metrics", "desc", desc, "err", err)
+	if err := c.collect(ch); err != nil {
+		_ = level.Error(c.logger).Log("msg", "failed collecting cpu_info metrics", "err", err)
 		return err
 	}
 	return nil
 }
 
-func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, error) {
+func (c *collector) collect(ch chan<- prometheus.Metric) error {
 	var dst []win32_Processor
 	// We use a static query here because the provided methods in wmi.go all issue a SELECT *;
 	// This results in the time-consuming LoadPercentage field being read which seems to measure each CPU
 	// serially over a 1 second interval, so the scrape time is at least 1s * num_sockets
 	if err := wmi.Query(win32ProcessorQuery, &dst); err != nil {
-		return nil, err
+		return err
 	}
 	if len(dst) == 0 {
-		return nil, errors.New("WMI query returned empty result set")
+		return errors.New("WMI query returned empty result set")
 	}
 
 	// Some CPUs end up exposing trailing spaces for certain strings, so clean them up
@@ -121,5 +121,5 @@ func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, erro
 		)
 	}
 
-	return nil, nil
+	return nil
 }

pkg/collector/cs/cs.go

@@ -77,21 +77,21 @@ func (c *collector) Build() error {
 // Collect sends the metric values for each metric
 // to the provided prometheus Metric channel.
 func (c *collector) Collect(_ *types.ScrapeContext, ch chan<- prometheus.Metric) error {
-	if desc, err := c.collect(ch); err != nil {
-		_ = level.Error(c.logger).Log("msg", "failed collecting cs metrics", "desc", desc, "err", err)
+	if err := c.collect(ch); err != nil {
+		_ = level.Error(c.logger).Log("msg", "failed collecting cs metrics", "err", err)
 		return err
 	}
 	return nil
 }
 
-func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, error) {
+func (c *collector) collect(ch chan<- prometheus.Metric) error {
 	// Get systeminfo for number of processors
 	systemInfo := sysinfoapi.GetSystemInfo()
 
 	// Get memory status for physical memory
 	mem, err := sysinfoapi.GlobalMemoryStatusEx()
 	if err != nil {
-		return nil, err
+		return err
 	}
 
 	ch <- prometheus.MustNewConstMetric(
@@ -108,15 +108,15 @@ func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, erro
 
 	hostname, err := sysinfoapi.GetComputerName(sysinfoapi.ComputerNameDNSHostname)
 	if err != nil {
-		return nil, err
+		return err
 	}
 	domain, err := sysinfoapi.GetComputerName(sysinfoapi.ComputerNameDNSDomain)
 	if err != nil {
-		return nil, err
+		return err
 	}
 	fqdn, err := sysinfoapi.GetComputerName(sysinfoapi.ComputerNameDNSFullyQualified)
 	if err != nil {
-		return nil, err
+		return err
 	}
 
 	ch <- prometheus.MustNewConstMetric(
@@ -128,5 +128,5 @@ func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, erro
 		fqdn,
 	)
 
-	return nil, nil
+	return nil
 }

pkg/collector/diskdrive/diskdrive.go

@@ -150,21 +150,21 @@ var (
 
 // Collect sends the metric values for each metric to the provided prometheus Metric channel.
 func (c *collector) Collect(_ *types.ScrapeContext, ch chan<- prometheus.Metric) error {
-	if desc, err := c.collect(ch); err != nil {
-		_ = level.Error(c.logger).Log("msg", "failed collecting disk_drive_info metrics", "desc", desc, "err", err)
+	if err := c.collect(ch); err != nil {
+		_ = level.Error(c.logger).Log("msg", "failed collecting disk_drive_info metrics", "err", err)
 		return err
 	}
 	return nil
 }
 
-func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, error) {
+func (c *collector) collect(ch chan<- prometheus.Metric) error {
 	var dst []Win32_DiskDrive
 
 	if err := wmi.Query(win32DiskQuery, &dst); err != nil {
-		return nil, err
+		return err
 	}
 	if len(dst) == 0 {
-		return nil, errors.New("WMI query returned empty result set")
+		return errors.New("WMI query returned empty result set")
 	}
 
 	for _, disk := range dst {
@@ -222,5 +222,5 @@ func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, erro
 		}
 	}
 
-	return nil, nil
+	return nil
 }

pkg/collector/dns/dns.go

@@ -208,8 +208,8 @@ func (c *collector) Build() error {
 // Collect sends the metric values for each metric
 // to the provided prometheus Metric channel.
 func (c *collector) Collect(_ *types.ScrapeContext, ch chan<- prometheus.Metric) error {
-	if desc, err := c.collect(ch); err != nil {
-		_ = level.Error(c.logger).Log("msg", "failed collecting dns metrics", "desc", desc, "err", err)
+	if err := c.collect(ch); err != nil {
+		_ = level.Error(c.logger).Log("msg", "failed collecting dns metrics", "err", err)
 		return err
 	}
 	return nil
@@ -261,14 +261,14 @@ type Win32_PerfRawData_DNS_DNS struct {
 	ZoneTransferSOARequestSent     uint32
 }
 
-func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, error) {
+func (c *collector) collect(ch chan<- prometheus.Metric) error {
 	var dst []Win32_PerfRawData_DNS_DNS
 	q := wmi.QueryAll(&dst, c.logger)
 	if err := wmi.Query(q, &dst); err != nil {
-		return nil, err
+		return err
 	}
 	if len(dst) == 0 {
-		return nil, errors.New("WMI query returned empty result set")
+		return errors.New("WMI query returned empty result set")
 	}
 
 	ch <- prometheus.MustNewConstMetric(
@@ -520,5 +520,5 @@ func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, erro
 		float64(dst[0].SecureUpdateReceived),
 	)
 
-	return nil, nil
+	return nil
 }

pkg/collector/fsrmquota/fsrmquota.go

@@ -118,8 +118,8 @@ func (c *collector) Build() error {
 // Collect sends the metric values for each metric
 // to the provided prometheus Metric channel.
 func (c *collector) Collect(_ *types.ScrapeContext, ch chan<- prometheus.Metric) error {
-	if desc, err := c.collect(ch); err != nil {
-		_ = level.Error(c.logger).Log("msg", "failed collecting fsrmquota metrics", "desc", desc, "err", err)
+	if err := c.collect(ch); err != nil {
+		_ = level.Error(c.logger).Log("msg", "failed collecting fsrmquota metrics", "err", err)
 		return err
 	}
 	return nil
@@ -142,14 +142,14 @@ type MSFT_FSRMQuota struct {
 	SoftLimit       bool
 }
 
-func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, error) {
+func (c *collector) collect(ch chan<- prometheus.Metric) error {
 	var dst []MSFT_FSRMQuota
 	q := wmi.QueryAll(&dst, c.logger)
 
 	var count int
 
 	if err := wmi.QueryNamespace(q, &dst, "root/microsoft/windows/fsrm"); err != nil {
-		return nil, err
+		return err
 	}
 
 	for _, quota := range dst {
@@ -214,5 +214,5 @@ func (c *collector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, erro
 		prometheus.GaugeValue,
 		float64(count),
 	)
-	return nil, nil
+	return nil
 }