enabled and fixed the errcheck linter rule

.golangci.yml

@@ -9,7 +9,7 @@ linters:
     - ineffassign
     - unused
     - govet
-    #- errcheck
+    - errcheck
     - staticcheck
   exclusions:
     generated: lax

cmd/healthchecker/health_checker.go

@@ -39,11 +39,18 @@ func main() {
 		}
 	})
 	pflag.CommandLine.AddGoFlagSet(flag.CommandLine)
-	pflag.CommandLine.MarkHidden("vmodule")
-	pflag.CommandLine.MarkHidden("logtostderr")
+	if err := pflag.CommandLine.MarkHidden("vmodule"); err != nil {
+		klog.Fatalf("Failed to mark hidden flag 'vmodule': %v", err)
+	}
+	if err := pflag.CommandLine.MarkHidden("logtostderr"); err != nil {
+		klog.Fatalf("Failed to mark hidden flag 'logtostderr': %v", err)
+	}
 
 	hco := options.NewHealthCheckerOptions()
-	hco.AddFlags(pflag.CommandLine)
+	if err := hco.AddFlags(pflag.CommandLine); err != nil {
+		fmt.Println(err)
+		os.Exit(int(types.Unknown))
+	}
 	pflag.Parse()
 	hco.SetDefaults()
 	if err := hco.IsValid(); err != nil {

cmd/healthchecker/options/options.go

@@ -47,12 +47,14 @@ type HealthCheckerOptions struct {
 }
 
 // AddFlags adds health checker command line options to pflag.
-func (hco *HealthCheckerOptions) AddFlags(fs *pflag.FlagSet) {
+func (hco *HealthCheckerOptions) AddFlags(fs *pflag.FlagSet) error {
 	fs.StringVar(&hco.Component, "component", types.KubeletComponent,
 		"The component to check health for. Supports kubelet, docker, kube-proxy, and cri")
 	// Deprecated: For backward compatibility on linux environment. Going forward "service" will be used instead of systemd-service
 	if runtime.GOOS == "linux" {
-		fs.MarkDeprecated("systemd-service", "please use --service flag instead")
+		if err := fs.MarkDeprecated("systemd-service", "please use --service flag instead"); err != nil {
+			return fmt.Errorf("failed to mark deprecated flag 'systemd-service': %w", err)
+		}
 		fs.StringVar(&hco.Service, "systemd-service", "",
 			"The underlying service responsible for the component. Set to the corresponding component for docker and kubelet, containerd for cri.")
 	}
@@ -73,6 +75,7 @@ func (hco *HealthCheckerOptions) AddFlags(fs *pflag.FlagSet) {
 		"The time to wait before marking the component as unhealthy.")
 	fs.Var(&hco.LogPatterns, "log-pattern",
 		"The log pattern to look for in service journald logs. The format for flag value <failureThresholdCount>:<logPattern>")
+	return nil
 }
 
 // IsValid validates health checker command line options.

cmd/nodeproblemdetector/node_problem_detector_test.go

@@ -96,7 +96,9 @@ func writeTempFile(t *testing.T, ext string, contents string) (string, error) {
 	fileName := f.Name()
 
 	if err := os.WriteFile(fileName, []byte(contents), 0o644); err != nil {
-		os.Remove(fileName)
+		if err := os.Remove(fileName); err != nil {
+			t.Logf("Failed to remove temporary file %s: %v", fileName, err)
+		}
 		return "", fmt.Errorf("cannot write config to temp file %s, %v", fileName, err)
 	}
 
@@ -106,16 +108,22 @@ func writeTempFile(t *testing.T, ext string, contents string) (string, error) {
 func setupNPD(t *testing.T) (*options.NodeProblemDetectorOptions, func()) {
 	fakeLogFileName, err := writeTempFile(t, "log", "")
 	if err != nil {
-		os.Remove(fakeLogFileName)
+		if err := os.Remove(fakeLogFileName); err != nil {
+			t.Logf("Failed to remove temporary file %s: %v", fakeLogFileName, err)
+		}
 		t.Fatalf("cannot create temp config file, %v", err)
 	}
 
 	fakeConfigFileContents := fmt.Sprintf(fakeConfigFilePattern, strings.ReplaceAll(fakeLogFileName, "\\", "\\\\"))
 
 	fakeConfigFileName, err := writeTempFile(t, "json", fakeConfigFileContents)
 	if err != nil {
-		os.Remove(fakeLogFileName)
-		os.Remove(fakeConfigFileName)
+		if err := os.Remove(fakeLogFileName); err != nil {
+			t.Logf("Failed to remove temporary file %s: %v", fakeLogFileName, err)
+		}
+		if err := os.Remove(fakeConfigFileName); err != nil {
+			t.Logf("Failed to remove temporary file %s: %v", fakeConfigFileName, err)
+		}
 		t.Fatalf("cannot create temp config file, %v", err)
 	}
 
@@ -126,7 +134,11 @@ func setupNPD(t *testing.T) (*options.NodeProblemDetectorOptions, func()) {
 				},
 			},
 		}, func() {
-			os.Remove(fakeLogFileName)
-			os.Remove(fakeConfigFileName)
+			if err := os.Remove(fakeLogFileName); err != nil {
+				t.Logf("Failed to remove temporary file %s: %v", fakeLogFileName, err)
+			}
+			if err := os.Remove(fakeConfigFileName); err != nil {
+				t.Logf("Failed to remove temporary file %s: %v", fakeConfigFileName, err)
+			}
 		}
 }

cmd/nodeproblemdetector/node_problem_detector_unix.go

@@ -38,11 +38,17 @@ func main() {
 		}
 	})
 	pflag.CommandLine.AddGoFlagSet(flag.CommandLine)
-	pflag.CommandLine.MarkHidden("vmodule")
-	pflag.CommandLine.MarkHidden("logtostderr")
+	if err := pflag.CommandLine.MarkHidden("vmodule"); err != nil {
+		klog.Fatalf("Failed to mark hidden flag 'vmodule': %v", err)
+	}
+	if err := pflag.CommandLine.MarkHidden("logtostderr"); err != nil {
+		klog.Fatalf("Failed to mark hidden flag 'logtostderr': %v", err)
+	}
 
 	npdo := options.NewNodeProblemDetectorOptions()
-	npdo.AddFlags(pflag.CommandLine)
+	if err := npdo.AddFlags(pflag.CommandLine); err != nil {
+		klog.Fatalf("Failed to add flags: %v", err)
+	}
 
 	pflag.Parse()
 	if err := npdMain(context.Background(), npdo); err != nil {

cmd/nodeproblemdetector/node_problem_detector_windows.go

@@ -53,11 +53,17 @@ func main() {
 		}
 	})
 	pflag.CommandLine.AddGoFlagSet(flag.CommandLine)
-	pflag.CommandLine.MarkHidden("vmodule")
-	pflag.CommandLine.MarkHidden("logtostderr")
+	if err := pflag.CommandLine.MarkHidden("vmodule"); err != nil {
+		klog.Fatalf("Failed to mark hidden flag 'vmodule': %v", err)
+	}
+	if err := pflag.CommandLine.MarkHidden("logtostderr"); err != nil {
+		klog.Fatalf("Failed to mark hidden flag 'logtostderr': %v", err)
+	}
 
 	npdo := options.NewNodeProblemDetectorOptions()
-	npdo.AddFlags(pflag.CommandLine)
+	if err := npdo.AddFlags(pflag.CommandLine); err != nil {
+		klog.Fatalf("Failed to add flags: %v", err)
+	}
 
 	pflag.Parse()
 

cmd/options/options.go

@@ -106,13 +106,17 @@ func NewNodeProblemDetectorOptions() *NodeProblemDetectorOptions {
 }
 
 // AddFlags adds node problem detector command line options to pflag.
-func (npdo *NodeProblemDetectorOptions) AddFlags(fs *pflag.FlagSet) {
+func (npdo *NodeProblemDetectorOptions) AddFlags(fs *pflag.FlagSet) error {
 	fs.StringSliceVar(&npdo.SystemLogMonitorConfigPaths, "system-log-monitors",
 		[]string{}, "List of paths to system log monitor config files, comma separated.")
-	fs.MarkDeprecated("system-log-monitors", "replaced by --config.system-log-monitor. NPD will panic if both --system-log-monitors and --config.system-log-monitor are set.")
+	if err := fs.MarkDeprecated("system-log-monitors", "replaced by --config.system-log-monitor. NPD will panic if both --system-log-monitors and --config.system-log-monitor are set."); err != nil {
+		return fmt.Errorf("failed to mark 'system-log-monitors' as deprecated: %w", err)
+	}
 	fs.StringSliceVar(&npdo.CustomPluginMonitorConfigPaths, "custom-plugin-monitors",
 		[]string{}, "List of paths to custom plugin monitor config files, comma separated.")
-	fs.MarkDeprecated("custom-plugin-monitors", "replaced by --config.custom-plugin-monitor. NPD will panic if both --custom-plugin-monitors and --config.custom-plugin-monitor are set.")
+	if err := fs.MarkDeprecated("custom-plugin-monitors", "replaced by --config.custom-plugin-monitor. NPD will panic if both --custom-plugin-monitors and --config.custom-plugin-monitor are set."); err != nil {
+		return fmt.Errorf("failed to mark 'custom-plugin-monitors' as deprecated: %w", err)
+	}
 	fs.BoolVar(&npdo.EnableK8sExporter, "enable-k8s-exporter", true, "Enables reporting to Kubernetes API server.")
 	fs.StringVar(&npdo.EventNamespace, "event-namespace", "", "Namespace for recorded Kubernetes events.")
 	fs.StringVar(&npdo.ApiServerOverride, "apiserver-override",
@@ -149,6 +153,7 @@ func (npdo *NodeProblemDetectorOptions) AddFlags(fs *pflag.FlagSet) {
 				problemDaemonName,
 				problemdaemon.GetProblemDaemonHandlerOrDie(problemDaemonName).CmdOptionDescription))
 	}
+	return nil
 }
 
 // ValidOrDie validates node problem detector command line options.

pkg/custompluginmonitor/plugin/plugin_test.go

@@ -103,7 +103,9 @@ func TestNewPluginRun(t *testing.T) {
 		utMeta := v
 		t.Run(desp, func(t *testing.T) {
 			conf := cpmtypes.CustomPluginConfig{}
-			(&conf).ApplyConfiguration()
+			if err := (&conf).ApplyConfiguration(); err != nil {
+				t.Errorf("Failed to apply configuration: %v", err)
+			}
 			p := Plugin{config: conf}
 			gotExitStatus, gotOutput := p.run(utMeta.Rule)
 			// cut at position max_output_length if expected output is longer than max_output_length bytes

pkg/custompluginmonitor/types/config_test.go

@@ -219,7 +219,9 @@ func TestCustomPluginConfigApplyConfiguration(t *testing.T) {
 	}
 
 	for desp, utMeta := range utMetas {
-		(&utMeta.Orig).ApplyConfiguration()
+		if err := (&utMeta.Orig).ApplyConfiguration(); err != nil {
+			t.Errorf("Error in apply configuration for %q: %v", desp, err)
+		}
 		if !reflect.DeepEqual(utMeta.Orig, utMeta.Wanted) {
 			t.Errorf("Error in apply configuration for %q", desp)
 			t.Errorf("Wanted: %+v. \nGot: %+v", utMeta.Wanted, utMeta.Orig)

pkg/exporters/k8sexporter/k8s_exporter.go

@@ -94,7 +94,9 @@ func (ke *k8sExporter) startHTTPReporting(npdo *options.NodeProblemDetectorOptio
 	// logic in the future.
 	mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusOK)
-		w.Write([]byte("ok"))
+		if _, err := w.Write([]byte("ok")); err != nil {
+			klog.Errorf("Failed to write response: %v", err)
+		}
 	})
 
 	// Add the handler to serve condition http request.

pkg/healthchecker/health_checker_linux.go

@@ -65,13 +65,19 @@ func getRepairFunc(hco *options.HealthCheckerOptions) func() {
 		// Use "docker ps" for docker health check. Not using crictl for docker to remove
 		// dependency on the kubelet.
 		return func() {
-			execCommand(types.CmdTimeout, "pkill", "-SIGUSR1", "dockerd")
-			execCommand(types.CmdTimeout, "systemctl", "kill", "--kill-who=main", hco.Service)
+			if _, err := execCommand(types.CmdTimeout, "pkill", "-SIGUSR1", "dockerd"); err != nil {
+				klog.Errorf("Failed to send SIGUSR1 to dockerd: %v", err)
+			}
+			if _, err := execCommand(types.CmdTimeout, "systemctl", "kill", "--kill-who=main", hco.Service); err != nil {
+				klog.Errorf("Failed to kill service %s: %v", hco.Service, err)
+			}
 		}
 	default:
 		// Just kill the service for all other components
 		return func() {
-			execCommand(types.CmdTimeout, "systemctl", "kill", "--kill-who=main", hco.Service)
+			if _, err := execCommand(types.CmdTimeout, "systemctl", "kill", "--kill-who=main", hco.Service); err != nil {
+				klog.Errorf("Failed to kill service %s: %v", hco.Service, err)
+			}
 		}
 	}
 }

pkg/problemmetrics/problem_metrics_test.go

@@ -118,7 +118,9 @@ func TestNewProblem(t *testing.T) {
 			pmm, fakeProblemCounter, fakeProblemGauge := NewProblemMetricsManagerStub()
 
 			for idx, reason := range test.reasons {
-				pmm.IncrementProblemCounter(reason, test.counts[idx])
+				if err := pmm.IncrementProblemCounter(reason, test.counts[idx]); err != nil {
+					t.Errorf("unexpected error: %v", err)
+				}
 			}
 
 			gotMetrics := append(fakeProblemCounter.ListMetrics(), fakeProblemGauge.ListMetrics()...)
@@ -266,7 +268,9 @@ func TestSetProblemGauge(t *testing.T) {
 			pmm, fakeProblemCounter, fakeProblemGauge := NewProblemMetricsManagerStub()
 
 			for _, argument := range test.arguments {
-				pmm.SetProblemGauge(argument.problemType, argument.reason, argument.value)
+				if err := pmm.SetProblemGauge(argument.problemType, argument.reason, argument.value); err != nil {
+					t.Errorf("unexpected error: %v", err)
+				}
 			}
 
 			gotMetrics := append(fakeProblemCounter.ListMetrics(), fakeProblemGauge.ListMetrics()...)

pkg/systemlogmonitor/logwatchers/filelog/log_watcher.go

@@ -91,7 +91,9 @@ const watchPollInterval = 500 * time.Millisecond
 // watchLoop is the main watch loop of filelog watcher.
 func (s *filelogWatcher) watchLoop() {
 	defer func() {
-		s.closer.Close()
+		if err := s.closer.Close(); err != nil {
+			klog.Errorf("Failed to close log file: %v", err)
+		}
 		close(s.logCh)
 		s.tomb.Done()
 	}()

pkg/systemlogmonitor/logwatchers/filelog/log_watcher_test.go

@@ -141,8 +141,12 @@ Jan  2 03:04:05 kernel: [2.000000] 3
 		f, err := os.CreateTemp("", "log_watcher_test")
 		assert.NoError(t, err)
 		defer func() {
-			f.Close()
-			os.Remove(f.Name())
+			if err := f.Close(); err != nil {
+				t.Logf("failed to close temporary file %s: %v", f.Name(), err)
+			}
+			if err := os.Remove(f.Name()); err != nil {
+				t.Logf("failed to remove temporary file %s: %v", f.Name(), err)
+			}
 		}()
 		_, err = f.Write([]byte(test.log))
 		assert.NoError(t, err)

pkg/systemlogmonitor/logwatchers/kmsg/log_watcher_linux.go

@@ -77,7 +77,9 @@ func (k *kernelLogWatcher) Watch() (<-chan *logtypes.Log, error) {
 
 // Stop closes the kmsgparser
 func (k *kernelLogWatcher) Stop() {
-	k.kmsgParser.Close()
+	if err := k.kmsgParser.Close(); err != nil {
+		klog.Errorf("Failed to close kmsg parser: %v", err)
+	}
 	k.tomb.Stop()
 }
 

pkg/systemstatsmonitor/cpu_collector.go

@@ -187,34 +187,54 @@ func (cc *cpuCollector) recordUsage() {
 	}
 	timersStat := timersStats[0]
 
-	cc.mUsageTime.Record(map[string]string{stateLabel: "user"}, clockTick*timersStat.User-cc.lastUsageTime["user"])
+	if err := cc.mUsageTime.Record(map[string]string{stateLabel: "user"}, clockTick*timersStat.User-cc.lastUsageTime["user"]); err != nil {
+		klog.Errorf("Failed to record cpu usage time for user: %v", err)
+	}
 	cc.lastUsageTime["user"] = clockTick * timersStat.User
 
-	cc.mUsageTime.Record(map[string]string{stateLabel: "system"}, clockTick*timersStat.System-cc.lastUsageTime["system"])
+	if err := cc.mUsageTime.Record(map[string]string{stateLabel: "system"}, clockTick*timersStat.System-cc.lastUsageTime["system"]); err != nil {
+		klog.Errorf("Failed to record cpu usage time for system: %v", err)
+	}
 	cc.lastUsageTime["system"] = clockTick * timersStat.System
 
-	cc.mUsageTime.Record(map[string]string{stateLabel: "idle"}, clockTick*timersStat.Idle-cc.lastUsageTime["idle"])
+	if err := cc.mUsageTime.Record(map[string]string{stateLabel: "idle"}, clockTick*timersStat.Idle-cc.lastUsageTime["idle"]); err != nil {
+		klog.Errorf("Failed to record cpu usage time for idle: %v", err)
+	}
 	cc.lastUsageTime["idle"] = clockTick * timersStat.Idle
 
-	cc.mUsageTime.Record(map[string]string{stateLabel: "nice"}, clockTick*timersStat.Nice-cc.lastUsageTime["nice"])
+	if err := cc.mUsageTime.Record(map[string]string{stateLabel: "nice"}, clockTick*timersStat.Nice-cc.lastUsageTime["nice"]); err != nil {
+		klog.Errorf("Failed to record cpu usage time for nice: %v", err)
+	}
 	cc.lastUsageTime["nice"] = clockTick * timersStat.Nice
 
-	cc.mUsageTime.Record(map[string]string{stateLabel: "iowait"}, clockTick*timersStat.Iowait-cc.lastUsageTime["iowait"])
+	if err := cc.mUsageTime.Record(map[string]string{stateLabel: "iowait"}, clockTick*timersStat.Iowait-cc.lastUsageTime["iowait"]); err != nil {
+		klog.Errorf("Failed to record cpu usage time for iowait: %v", err)
+	}
 	cc.lastUsageTime["iowait"] = clockTick * timersStat.Iowait
 
-	cc.mUsageTime.Record(map[string]string{stateLabel: "irq"}, clockTick*timersStat.Irq-cc.lastUsageTime["irq"])
+	if err := cc.mUsageTime.Record(map[string]string{stateLabel: "irq"}, clockTick*timersStat.Irq-cc.lastUsageTime["irq"]); err != nil {
+		klog.Errorf("Failed to record cpu usage time for irq: %v", err)
+	}
 	cc.lastUsageTime["irq"] = clockTick * timersStat.Irq
 
-	cc.mUsageTime.Record(map[string]string{stateLabel: "softirq"}, clockTick*timersStat.Softirq-cc.lastUsageTime["softirq"])
+	if err := cc.mUsageTime.Record(map[string]string{stateLabel: "softirq"}, clockTick*timersStat.Softirq-cc.lastUsageTime["softirq"]); err != nil {
+		klog.Errorf("Failed to record cpu usage time for softirq: %v", err)
+	}
 	cc.lastUsageTime["softirq"] = clockTick * timersStat.Softirq
 
-	cc.mUsageTime.Record(map[string]string{stateLabel: "steal"}, clockTick*timersStat.Steal-cc.lastUsageTime["steal"])
+	if err := cc.mUsageTime.Record(map[string]string{stateLabel: "steal"}, clockTick*timersStat.Steal-cc.lastUsageTime["steal"]); err != nil {
+		klog.Errorf("Failed to record cpu usage time for steal: %v", err)
+	}
 	cc.lastUsageTime["steal"] = clockTick * timersStat.Steal
 
-	cc.mUsageTime.Record(map[string]string{stateLabel: "guest"}, clockTick*timersStat.Guest-cc.lastUsageTime["guest"])
+	if err := cc.mUsageTime.Record(map[string]string{stateLabel: "guest"}, clockTick*timersStat.Guest-cc.lastUsageTime["guest"]); err != nil {
+		klog.Errorf("Failed to record cpu usage time for guest: %v", err)
+	}
 	cc.lastUsageTime["guest"] = clockTick * timersStat.Guest
 
-	cc.mUsageTime.Record(map[string]string{stateLabel: "guest_nice"}, clockTick*timersStat.GuestNice-cc.lastUsageTime["guest_nice"])
+	if err := cc.mUsageTime.Record(map[string]string{stateLabel: "guest_nice"}, clockTick*timersStat.GuestNice-cc.lastUsageTime["guest_nice"]); err != nil {
+		klog.Errorf("Failed to record cpu usage time for guest_nice: %v", err)
+	}
 	cc.lastUsageTime["guest_nice"] = clockTick * timersStat.GuestNice
 }