chore: Fix warnings

Fixing warnings in cloudflared log collector.

This attempts to fix errors like the ones shown below:

```
diagnostic/diagnostic.go:132:23: Error return value of `logHandle.Close` is not checked (errcheck)
	defer logHandle.Close()

diagnostic/diagnostic.go:134:26: G303: File creation in shared tmp directory without using ioutil.Tempfile (gosec)
	outputLogHandle, err := os.Create(filepath.Join(os.TempDir(), logFilename))
```

diagnostic/diagnostic.go

@@ -126,13 +126,14 @@ func collectLogs(
 	if err != nil {
 		return "", fmt.Errorf("error opening log file while collecting logs: %w", err)
 	}
-	defer logHandle.Close()
+	defer func() { _ = logHandle.Close() }()
 
+	// nolint: gosec
 	outputLogHandle, err := os.Create(filepath.Join(os.TempDir(), logFilename))
 	if err != nil {
 		return "", ErrCreatingTemporaryFile
 	}
-	defer outputLogHandle.Close()
+	defer func() { _ = outputLogHandle.Close() }()
 
 	_, err = io.Copy(outputLogHandle, logHandle)
 	if err != nil {
@@ -229,12 +230,13 @@ func networkInformationCollectors() (rawNetworkCollector, jsonNetworkCollector c
 }
 
 func rawNetworkInformationWriter(resultMap map[string]networkCollectionResult) (string, error) {
+	// nolint: gosec
 	networkDumpHandle, err := os.Create(filepath.Join(os.TempDir(), rawNetworkBaseName))
 	if err != nil {
 		return "", ErrCreatingTemporaryFile
 	}
 
-	defer networkDumpHandle.Close()
+	defer func() { _ = networkDumpHandle.Close() }()
 
 	var exitErr error
 
@@ -260,12 +262,13 @@ func rawNetworkInformationWriter(resultMap map[string]networkCollectionResult) (
 }
 
 func jsonNetworkInformationWriter(resultMap map[string]networkCollectionResult) (string, error) {
+	// nolint: gosec
 	networkDumpHandle, err := os.Create(filepath.Join(os.TempDir(), networkBaseName))
 	if err != nil {
 		return "", ErrCreatingTemporaryFile
 	}
 
-	defer networkDumpHandle.Close()
+	defer func() { _ = networkDumpHandle.Close() }()
 
 	encoder := newFormattedEncoder(networkDumpHandle)
 
@@ -290,11 +293,12 @@ func jsonNetworkInformationWriter(resultMap map[string]networkCollectionResult)
 
 func collectFromEndpointAdapter(collect collectToWriterFunc, fileName string) collectFunc {
 	return func(ctx context.Context) (string, error) {
+		// nolint: gosec
 		dumpHandle, err := os.Create(filepath.Join(os.TempDir(), fileName))
 		if err != nil {
 			return "", ErrCreatingTemporaryFile
 		}
-		defer dumpHandle.Close()
+		defer func() { _ = dumpHandle.Close() }()
 
 		err = collect(ctx, dumpHandle)
 		if err != nil {
@@ -349,12 +353,12 @@ func resolveInstanceBaseURL(
 		if !strings.HasPrefix(metricsServerAddress, "http://") {
 			metricsServerAddress = "http://" + metricsServerAddress
 		}
-		url, err := url.Parse(metricsServerAddress)
+		baseUrl, err := url.Parse(metricsServerAddress)
 		if err != nil {
 			return nil, nil, nil, fmt.Errorf("provided address is not valid: %w", err)
 		}
 
-		return url, nil, nil, nil
+		return baseUrl, nil, nil, nil
 	}
 
 	tunnelState, foundTunnelStates, err := FindMetricsServer(log, client, addresses)
@@ -436,11 +440,12 @@ func createJobs(
 }
 
 func createTaskReport(taskReport map[string]taskResult) (string, error) {
+	// nolint: gosec
 	dumpHandle, err := os.Create(filepath.Join(os.TempDir(), taskResultBaseName))
 	if err != nil {
 		return "", ErrCreatingTemporaryFile
 	}
-	defer dumpHandle.Close()
+	defer func() { _ = dumpHandle.Close() }()
 
 	encoder := newFormattedEncoder(dumpHandle)
 
@@ -545,7 +550,7 @@ func RunDiagnostic(
 
 		defer func() {
 			if !errors.Is(v.Err, ErrCreatingTemporaryFile) {
-				os.Remove(v.path)
+				_ = os.Remove(v.path)
 			}
 		}()
 	}

diagnostic/log_collector_docker.go

@@ -20,18 +20,18 @@ func NewDockerLogCollector(containerID string) *DockerLogCollector {
 }
 
 func (collector *DockerLogCollector) Collect(ctx context.Context) (*LogInformation, error) {
-	tmp := os.TempDir()
-
-	outputHandle, err := os.Create(filepath.Join(tmp, logFilename))
+	// nolint: gosec
+	outputHandle, err := os.Create(filepath.Join(os.TempDir(), logFilename))
 	if err != nil {
 		return nil, fmt.Errorf("error opening output file: %w", err)
 	}
 
-	defer outputHandle.Close()
+	defer func() { _ = outputHandle.Close() }()
 
 	// Calculate 2 weeks ago
 	since := time.Now().Add(twoWeeksOffset).Format(time.RFC3339)
 
+	// nolint: gosec
 	command := exec.CommandContext(
 		ctx,
 		"docker",

diagnostic/log_collector_host.go

@@ -13,7 +13,6 @@ const (
 	linuxManagedLogsPath          = "/var/log/cloudflared.err"
 	darwinManagedLogsPath         = "/Library/Logs/com.cloudflare.cloudflared.err.log"
 	linuxServiceConfigurationPath = "/etc/systemd/system/cloudflared.service"
-	linuxSystemdPath              = "/run/systemd/system"
 )
 
 type HostLogCollector struct {
@@ -27,14 +26,13 @@ func NewHostLogCollector(client HTTPClient) *HostLogCollector {
 }
 
 func extractLogsFromJournalCtl(ctx context.Context) (*LogInformation, error) {
-	tmp := os.TempDir()
-
-	outputHandle, err := os.Create(filepath.Join(tmp, logFilename))
+	// nolint: gosec
+	outputHandle, err := os.Create(filepath.Join(os.TempDir(), logFilename))
 	if err != nil {
 		return nil, fmt.Errorf("error opening output file: %w", err)
 	}
 
-	defer outputHandle.Close()
+	defer func() { _ = outputHandle.Close() }()
 
 	command := exec.CommandContext(
 		ctx,

diagnostic/log_collector_kubernetes.go

@@ -22,18 +22,19 @@ func NewKubernetesLogCollector(containerID, pod string) *KubernetesLogCollector
 }
 
 func (collector *KubernetesLogCollector) Collect(ctx context.Context) (*LogInformation, error) {
-	tmp := os.TempDir()
-	outputHandle, err := os.Create(filepath.Join(tmp, logFilename))
+	// nolint: gosec
+	outputHandle, err := os.Create(filepath.Join(os.TempDir(), logFilename))
 	if err != nil {
 		return nil, fmt.Errorf("error opening output file: %w", err)
 	}
 
-	defer outputHandle.Close()
+	defer func() { _ = outputHandle.Close() }()
 
 	var command *exec.Cmd
 	// Calculate 2 weeks ago
 	since := time.Now().Add(twoWeeksOffset).Format(time.RFC3339)
 	if collector.containerID != "" {
+		// nolint: gosec
 		command = exec.CommandContext(
 			ctx,
 			"kubectl",
@@ -47,6 +48,7 @@ func (collector *KubernetesLogCollector) Collect(ctx context.Context) (*LogInfor
 			collector.containerID,
 		)
 	} else {
+		// nolint: gosec
 		command = exec.CommandContext(
 			ctx,
 			"kubectl",

diagnostic/log_collector_utils.go

@@ -67,6 +67,8 @@ func PipeCommandOutputToFile(command *exec.Cmd, outputHandle *os.File) (*LogInfo
 }
 
 func CopyFilesFromDirectory(path string) (string, error) {
+	const defaultLogFilename = "cloudflared.log"
+
 	// rolling logs have as suffix the current date thus
 	// when iterating the path files they are already in
 	// chronological order
@@ -75,30 +77,32 @@ func CopyFilesFromDirectory(path string) (string, error) {
 		return "", fmt.Errorf("error reading directory %s: %w", path, err)
 	}
 
+	// nolint: gosec
 	outputHandle, err := os.Create(filepath.Join(os.TempDir(), logFilename))
 	if err != nil {
-		return "", fmt.Errorf("creating file %s: %w", outputHandle.Name(), err)
+		return "", fmt.Errorf("creating temporary log file %s: %w", logFilename, err)
 	}
-	defer outputHandle.Close()
+	defer func() { _ = outputHandle.Close() }()
 
 	for _, file := range files {
+		// nolint: gosec
 		logHandle, err := os.Open(filepath.Join(path, file.Name()))
 		if err != nil {
-			return "", fmt.Errorf("error opening file %s:%w", file.Name(), err)
+			return "", fmt.Errorf("error opening file %s: %w", file.Name(), err)
 		}
-		defer logHandle.Close()
-
 		_, err = io.Copy(outputHandle, logHandle)
+		_ = logHandle.Close()
 		if err != nil {
-			return "", fmt.Errorf("error copying file %s:%w", logHandle.Name(), err)
+			return "", fmt.Errorf("error copying file %s: %w", file.Name(), err)
 		}
 	}
 
-	logHandle, err := os.Open(filepath.Join(path, "cloudflared.log"))
+	// nolint: gosec
+	logHandle, err := os.Open(filepath.Join(path, defaultLogFilename))
 	if err != nil {
-		return "", fmt.Errorf("error opening file %s:%w", logHandle.Name(), err)
+		return "", fmt.Errorf("error opening file %s:%w", defaultLogFilename, err)
 	}
-	defer logHandle.Close()
+	defer func() { _ = logHandle.Close() }()
 
 	_, err = io.Copy(outputHandle, logHandle)
 	if err != nil {