Make error message styling consistent

The purpose of this PR is to achieve consistent error message styling. Styling follows the following conventions:

1. Error strings should not be capitalized (unless beginning with an exported name, a proper noun or an acronym) and should not end with punctuation. 

2. Error message is separated from the main message string using `;` separator.

3. Use of `%w` in place of `%v` to make it available to `errors.Is` and `errors.As` when supporting custom errors in future.

.gitignore

@@ -15,31 +15,35 @@ vendor/
 # Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio, WebStorm and Rider
 # Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
 
+## Directory-based project format:
+.idea/
+# if you decide to remove above rule then ignore the following:
+
 # User-specific stuff
-.idea/**/workspace.xml
-.idea/**/tasks.xml
-.idea/**/usage.statistics.xml
-.idea/**/dictionaries
-.idea/**/shelf
+#.idea/**/workspace.xml
+#.idea/**/tasks.xml
+#.idea/**/usage.statistics.xml
+#.idea/**/dictionaries
+#.idea/**/shelf
 
 # AWS User-specific
-.idea/**/aws.xml
+#.idea/**/aws.xml
 
 # Generated files
-.idea/**/contentModel.xml
+#.idea/**/contentModel.xml
 
 # Sensitive or high-churn files
-.idea/**/dataSources/
-.idea/**/dataSources.ids
-.idea/**/dataSources.local.xml
-.idea/**/sqlDataSources.xml
-.idea/**/dynamic.xml
-.idea/**/uiDesigner.xml
-.idea/**/dbnavigator.xml
+#.idea/**/dataSources/
+#.idea/**/dataSources.ids
+#.idea/**/dataSources.local.xml
+#.idea/**/sqlDataSources.xml
+#.idea/**/dynamic.xml
+#.idea/**/uiDesigner.xml
+#.idea/**/dbnavigator.xml
 
 # Gradle
-.idea/**/gradle.xml
-.idea/**/libraries
+#.idea/**/gradle.xml
+#.idea/**/libraries
 
 # Gradle and Maven with auto-import
 # When using Gradle or Maven with auto-import, you should exclude module files,

internal/pkg/nvmlprovider/provider.go

@@ -43,7 +43,7 @@ func GetMIGDeviceInfoByID(uuid string) (*MIGDeviceInfo, error) {
 		ret := nvml.Init()
 		if ret != nvml.SUCCESS {
 			err = errors.New(nvml.ErrorString(ret))
-			logrus.Error("Can not init NVML library")
+			logrus.Error("Can not init NVML library.")
 		}
 	})
 	if err != nil {
@@ -88,22 +88,22 @@ func GetMIGDeviceInfoByID(uuid string) (*MIGDeviceInfo, error) {
 
 	tokens := strings.SplitN(uuid, "-", 2)
 	if len(tokens) != 2 || tokens[0] != "MIG" {
-		return nil, fmt.Errorf("Unable to parse UUID as MIG device")
+		return nil, fmt.Errorf("unable to parse UUID '%s' as MIG device", uuid)
 	}
 
 	tokens = strings.SplitN(tokens[1], "/", 3)
 	if len(tokens) != 3 || !strings.HasPrefix(tokens[0], "GPU-") {
-		return nil, fmt.Errorf("Unable to parse UUID as MIG device")
+		return nil, fmt.Errorf("unable to parse UUID '%s' as MIG device", uuid)
 	}
 
 	gi, err := strconv.Atoi(tokens[1])
 	if err != nil {
-		return nil, fmt.Errorf("Unable to parse UUID as MIG device")
+		return nil, fmt.Errorf("unable to parse UUID '%s' as MIG device", uuid)
 	}
 
 	ci, err := strconv.Atoi(tokens[2])
 	if err != nil {
-		return nil, fmt.Errorf("Unable to parse UUID as MIG device")
+		return nil, fmt.Errorf("unable to parse UUID '%s' as MIG device", uuid)
 	}
 
 	return &MIGDeviceInfo{

pkg/cmd/app.go

@@ -236,7 +236,7 @@ restart:
 	defer func() {
 		if r := recover(); r != nil {
 			logrus.WithField(dcgmexporter.LoggerStackTrace, string(debug.Stack())).Error("Encountered a failure.")
-			err = fmt.Errorf("Encountered a failure: %v", r)
+			err = fmt.Errorf("encountered a failure; err: %v", r)
 		}
 	}()
 
@@ -361,14 +361,15 @@ func parseDeviceOptions(devices string) (dcgmexporter.DeviceOptions, error) {
 	letterAndRange := strings.Split(devices, ":")
 	count := len(letterAndRange)
 	if count > 2 {
-		return dOpt, fmt.Errorf("Invalid ranged device option '%s': there can only be one specified range", devices)
+		return dOpt, fmt.Errorf("invalid ranged device option '%s'; err: there can only be one specified range",
+			devices)
 	}
 
 	letter := letterAndRange[0]
 	if letter == FlexKey {
 		dOpt.Flex = true
 		if count > 1 {
-			return dOpt, fmt.Errorf("No range can be specified with the flex option 'f'")
+			return dOpt, fmt.Errorf("no range can be specified with the flex option 'f'")
 		}
 	} else if letter == MajorKey || letter == MinorKey {
 		var indices []int
@@ -381,7 +382,7 @@ func parseDeviceOptions(devices string) (dcgmexporter.DeviceOptions, error) {
 				rangeTokens := strings.Split(numberOrRange, "-")
 				rangeTokenCount := len(rangeTokens)
 				if rangeTokenCount > 2 {
-					return dOpt, fmt.Errorf("A range can only be '<number>-<number>', but found '%s'", numberOrRange)
+					return dOpt, fmt.Errorf("range can only be '<number>-<number>', but found '%s'", numberOrRange)
 				} else if rangeTokenCount == 1 {
 					number, err := strconv.Atoi(rangeTokens[0])
 					if err != nil {
@@ -412,7 +413,7 @@ func parseDeviceOptions(devices string) (dcgmexporter.DeviceOptions, error) {
 			dOpt.MinorRange = indices
 		}
 	} else {
-		return dOpt, fmt.Errorf("The only valid options preceding ':<range>' are 'g' or 'i', but found '%s'", letter)
+		return dOpt, fmt.Errorf("valid options preceding ':<range>' are 'g' or 'i', but found '%s'", letter)
 	}
 
 	return dOpt, nil

pkg/dcgmexporter/const.go

@@ -44,7 +44,7 @@ func (d DCGMExporterMetric) String() string {
 func IdentifyMetricType(s string) (DCGMExporterMetric, error) {
 	mv, ok := DCGMFields[s]
 	if !ok {
-		return mv, fmt.Errorf("Unknown DCGMExporterMetric field '%s'", s)
+		return mv, fmt.Errorf("unknown DCGMExporterMetric field '%s'", s)
 	}
 	return mv, nil
 }

pkg/dcgmexporter/const_test.go

@@ -56,7 +56,7 @@ func TestIdentifyMetricType(t *testing.T) {
 				assert.NoError(t, err, "Expected metrics to be found.")
 				assert.Equal(t, output, tt.output, "Invalid output")
 			} else {
-				assert.Errorf(t, err, "Expected metrics to be not found")
+				assert.Errorf(t, err, "Expected metrics to be not found.")
 			}
 		})
 	}

pkg/dcgmexporter/dcgm.go

@@ -33,7 +33,7 @@ func NewGroup() (dcgm.GroupHandle, func(), error) {
 	return group, func() {
 		err := dcgm.DestroyGroup(group)
 		if err != nil {
-			logrus.WithError(err).Warn("Cannot destroy field group")
+			logrus.WithError(err).Warn("Cannot destroy field group.")
 		}
 	}, nil
 }
@@ -65,12 +65,14 @@ func NewFieldGroup(deviceFields []dcgm.Short) (dcgm.FieldHandle, func(), error)
 	return fieldGroup, func() {
 		err := dcgm.FieldGroupDestroy(fieldGroup)
 		if err != nil {
-			logrus.WithError(err).Warn("Cannot destroy field group")
+			logrus.WithError(err).Warn("Cannot destroy field group.")
 		}
 	}, nil
 }
 
-func WatchFieldGroup(group dcgm.GroupHandle, field dcgm.FieldHandle, updateFreq int64, maxKeepAge float64, maxKeepSamples int32) error {
+func WatchFieldGroup(
+	group dcgm.GroupHandle, field dcgm.FieldHandle, updateFreq int64, maxKeepAge float64, maxKeepSamples int32,
+) error {
 	err := dcgm.WatchFieldsWithGroupEx(field, group, updateFreq, maxKeepAge, maxKeepSamples)
 	if err != nil {
 		return err

pkg/dcgmexporter/gpu_collector.go

@@ -27,11 +27,12 @@ import (
 
 type DCGMCollectorConstructor func([]Counter, *Config, string, dcgm.Field_Entity_Group) (*DCGMCollector, func(), error)
 
-func NewDCGMCollector(c []Counter, config *Config, hostname string, entityType dcgm.Field_Entity_Group) (*DCGMCollector, func(), error) {
+func NewDCGMCollector(c []Counter, config *Config, hostname string, entityType dcgm.Field_Entity_Group) (*DCGMCollector,
+	func(), error) {
 	var deviceFields = NewDeviceFields(c, entityType)
 
 	if !ShouldMonitorDeviceType(deviceFields, entityType) {
-		return nil, func() {}, fmt.Errorf("No fields to watch for device type: %d", entityType)
+		return nil, func() {}, fmt.Errorf("no fields to watch for device type '%d'", entityType)
 	}
 
 	sysInfo, err := GetSystemInfo(config, entityType)
@@ -59,7 +60,8 @@ func NewDCGMCollector(c []Counter, config *Config, hostname string, entityType d
 }
 
 func GetSystemInfo(config *Config, entityType dcgm.Field_Entity_Group) (*SystemInfo, error) {
-	sysInfo, err := InitializeSystemInfo(config.GPUDevices, config.SwitchDevices, config.CPUDevices, config.UseFakeGPUs, entityType)
+	sysInfo, err := InitializeSystemInfo(config.GPUDevices, config.SwitchDevices, config.CPUDevices, config.UseFakeGPUs,
+		entityType)
 	if err != nil {
 		return nil, err
 	}
@@ -150,11 +152,13 @@ func FindCounterField(c []Counter, fieldId uint) (Counter, error) {
 		}
 	}
 
-	return c[0], fmt.Errorf("Could not find corresponding counter")
+	return c[0], fmt.Errorf("could not find counter corresponding to field ID '%d'", fieldId)
 }
 
-func ToSwitchMetric(metrics MetricsByCounter,
-	values []dcgm.FieldValue_v1, c []Counter, mi MonitoringInfo, useOld bool, hostname string) {
+func ToSwitchMetric(
+	metrics MetricsByCounter,
+	values []dcgm.FieldValue_v1, c []Counter, mi MonitoringInfo, useOld bool, hostname string,
+) {
 	labels := map[string]string{}
 
 	for _, val := range values {
@@ -196,8 +200,10 @@ func ToSwitchMetric(metrics MetricsByCounter,
 	}
 }
 
-func ToCPUMetric(metrics MetricsByCounter,
-	values []dcgm.FieldValue_v1, c []Counter, mi MonitoringInfo, useOld bool, hostname string) {
+func ToCPUMetric(
+	metrics MetricsByCounter,
+	values []dcgm.FieldValue_v1, c []Counter, mi MonitoringInfo, useOld bool, hostname string,
+) {
 	var labels = map[string]string{}
 
 	for _, val := range values {

pkg/dcgmexporter/kubernetes.go

@@ -25,11 +25,12 @@ import (
 	"strings"
 	"time"
 
-	"github.com/NVIDIA/dcgm-exporter/internal/pkg/nvmlprovider"
 	"github.com/sirupsen/logrus"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials/insecure"
 	podresourcesapi "k8s.io/kubelet/pkg/apis/podresources/v1alpha1"
+
+	"github.com/NVIDIA/dcgm-exporter/internal/pkg/nvmlprovider"
 )
 
 var (
@@ -114,7 +115,7 @@ func connectToServer(socket string) (*grpc.ClientConn, func(), error) {
 	)
 
 	if err != nil {
-		return nil, func() {}, fmt.Errorf("failure connecting to %s: %v", socket, err)
+		return nil, func() {}, fmt.Errorf("failure connecting to '%s'; err: %w", socket, err)
 	}
 
 	return conn, func() { conn.Close() }, nil
@@ -128,13 +129,15 @@ func (p *PodMapper) listPods(conn *grpc.ClientConn) (*podresourcesapi.ListPodRes
 
 	resp, err := client.List(ctx, &podresourcesapi.ListPodResourcesRequest{})
 	if err != nil {
-		return nil, fmt.Errorf("failure getting pod resources %v", err)
+		return nil, fmt.Errorf("failure getting pod resources; err: %w", err)
 	}
 
 	return resp, nil
 }
 
-func (p *PodMapper) toDeviceToPod(devicePods *podresourcesapi.ListPodResourcesResponse, sysInfo SystemInfo) map[string]PodInfo {
+func (p *PodMapper) toDeviceToPod(
+	devicePods *podresourcesapi.ListPodResourcesResponse, sysInfo SystemInfo,
+) map[string]PodInfo {
 	deviceToPodMap := make(map[string]PodInfo)
 
 	for _, pod := range devicePods.GetPodResources() {
@@ -159,7 +162,8 @@ func (p *PodMapper) toDeviceToPod(devicePods *podresourcesapi.ListPodResourcesRe
 					if strings.HasPrefix(deviceID, MIG_UUID_PREFIX) {
 						migDevice, err := nvmlGetMIGDeviceInfoByIDHook(deviceID)
 						if err == nil {
-							giIdentifier := GetGPUInstanceIdentifier(sysInfo, migDevice.ParentUUID, uint(migDevice.GPUInstanceID))
+							giIdentifier := GetGPUInstanceIdentifier(sysInfo, migDevice.ParentUUID,
+								uint(migDevice.GPUInstanceID))
 							deviceToPodMap[giIdentifier] = podInfo
 						}
 						gpuUUID := deviceID[len(MIG_UUID_PREFIX):]

pkg/dcgmexporter/kubernetes_test.go

@@ -24,14 +24,15 @@ import (
 	"testing"
 	"time"
 
-	"github.com/NVIDIA/dcgm-exporter/internal/pkg/nvmlprovider"
-	"github.com/NVIDIA/dcgm-exporter/internal/pkg/testutils"
 	"github.com/NVIDIA/go-dcgm/pkg/dcgm"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"google.golang.org/grpc"
 	podresourcesapi "k8s.io/kubernetes/pkg/kubelet/apis/podresources/v1alpha1"
 	"k8s.io/kubernetes/pkg/kubelet/util"
+
+	"github.com/NVIDIA/dcgm-exporter/internal/pkg/nvmlprovider"
+	"github.com/NVIDIA/dcgm-exporter/internal/pkg/testutils"
 )
 
 var tmpDir string
@@ -111,7 +112,7 @@ func StartMockServer(t *testing.T, server *grpc.Server, socket string) func() {
 		case <-stopped:
 			return
 		case <-time.After(1 * time.Second):
-			t.Fatal("Failed waiting for gRPC server to stop")
+			t.Fatal("Failed waiting for gRPC server to stop.")
 		}
 	}
 }
@@ -138,7 +139,9 @@ func NewPodResourcesMockServer(used []string) *PodResourcesMockServer {
 	}
 }
 
-func (s *PodResourcesMockServer) List(ctx context.Context, req *podresourcesapi.ListPodResourcesRequest) (*podresourcesapi.ListPodResourcesResponse, error) {
+func (s *PodResourcesMockServer) List(
+	ctx context.Context, req *podresourcesapi.ListPodResourcesRequest,
+) (*podresourcesapi.ListPodResourcesResponse, error) {
 	podResources := make([]*podresourcesapi.PodResources, len(s.gpus))
 
 	for i, gpu := range s.gpus {