chore: Upgrade golangci-lint to v2

- Migrate the configuration file
- Update the tooling version and CI
- Apply auto-fixes

Signed-off-by: Kemal Akkoyun <kemal.akkoyun@datadoghq.com>

.golangci.yml

@@ -14,6 +14,7 @@ linters:
             - pkg: os/exec
               desc: Using os/exec to run sub processes it not allowed by policy
     errcheck:
+      # Used in HTTP handlers, any error is handled by the server itself.
       exclude-functions:
         - (net/http.ResponseWriter).Write
     revive:

collector/btrfs_linux.go

@@ -69,7 +69,7 @@ func (c *btrfsCollector) Update(ch chan<- prometheus.Metric) error {
 
 	for _, s := range stats {
 		// match up procfs and ioctl info by filesystem UUID (without dashes)
-		var fsUUID = strings.Replace(s.UUID, "-", "", -1)
+		var fsUUID = strings.ReplaceAll(s.UUID, "-", "")
 		ioctlStats := ioctlStatsMap[fsUUID]
 		c.updateBtrfsStats(ch, s, ioctlStats)
 	}

collector/cpu_linux.go

@@ -87,9 +87,9 @@ func NewCPUCollector(logger *slog.Logger) (Collector, error) {
 	isolcpus, err := sfs.IsolatedCPUs()
 	if err != nil {
 		if !os.IsNotExist(err) {
-			return nil, fmt.Errorf("Unable to get isolated cpus: %w", err)
+			return nil, fmt.Errorf("couldn't get isolated cpus: %w", err)
 		}
-		logger.Debug("Could not open isolated file", "error", err)
+		logger.Debug("couldn't open isolated file", "error", err)
 	}
 
 	c := &cpuCollector{

collector/ethtool_linux_test.go

@@ -212,16 +212,18 @@ func (e *EthtoolFixture) LinkInfo(intf string) (ethtool.EthtoolCmd, error) {
 
 		items := strings.Split(line, ": ")
 		if items[0] == "Supported pause frame use" {
-			if items[1] == "Symmetric" {
+			switch items[1] {
+			case "Symmetric":
 				res.Supported |= (1 << unix.ETHTOOL_LINK_MODE_Pause_BIT)
-			} else if items[1] == "Receive-only" {
+			case "Receive-only":
 				res.Supported |= (1 << unix.ETHTOOL_LINK_MODE_Asym_Pause_BIT)
 			}
 		}
 		if items[0] == "Advertised pause frame use" {
-			if items[1] == "Symmetric" {
+			switch items[1] {
+			case "Symmetric":
 				res.Advertising |= (1 << unix.ETHTOOL_LINK_MODE_Pause_BIT)
-			} else if items[1] == "Receive-only" {
+			case "Receive-only":
 				res.Advertising |= (1 << unix.ETHTOOL_LINK_MODE_Asym_Pause_BIT)
 			}
 		}

collector/filesystem_linux.go

@@ -215,8 +215,8 @@ func parseFilesystemLabels(r io.Reader) ([]filesystemLabels, error) {
 
 		// Ensure we handle the translation of \040 and \011
 		// as per fstab(5).
-		parts[4] = strings.Replace(parts[4], "\\040", " ", -1)
+		parts[4] = strings.ReplaceAll(parts[4], "\\040", " ")
-		parts[4] = strings.Replace(parts[4], "\\011", "\t", -1)
+		parts[4] = strings.ReplaceAll(parts[4], "\\011", "\t")
 
 		filesystems = append(filesystems, filesystemLabels{
 			device:      parts[m+3],

collector/meminfo_linux.go

@@ -44,7 +44,7 @@ func NewMeminfoCollector(logger *slog.Logger) (Collector, error) {
 func (c *meminfoCollector) getMemInfo() (map[string]float64, error) {
 	meminfo, err := c.fs.Meminfo()
 	if err != nil {
-		return nil, fmt.Errorf("Failed to get memory info: %s", err)
+		return nil, fmt.Errorf("failed to get memory info: %s", err)
 	}
 
 	metrics := make(map[string]float64)

collector/perf_linux_test.go

@@ -33,10 +33,10 @@ func canTestPerf(t *testing.T) {
 	if err != nil {
 		t.Skip("Procfs not mounted, skipping perf tests")
 	}
-	paranoidStr := strings.Replace(string(paranoidBytes), "\n", "", -1)
+	paranoidStr := strings.ReplaceAll(string(paranoidBytes), "\n", "")
 	paranoid, err := strconv.Atoi(paranoidStr)
 	if err != nil {
-		t.Fatalf("Expected perf_event_paranoid to be an int, got: %s", paranoidStr)
+		t.Fatalf("expected perf_event_paranoid to be an int, got: %s", paranoidStr)
 	}
 	if paranoid >= 1 {
 		t.Skip("Skipping perf tests, set perf_event_paranoid to 0")

collector/systemd_linux_test.go

@@ -122,11 +122,12 @@ func TestSystemdSummary(t *testing.T) {
 	summary := summarizeUnits(fixtures[0])
 
 	for _, state := range unitStatesName {
-		if state == "inactive" {
+		switch state {
+		case "inactive":
 			testSummaryHelper(t, state, summary[state], 3.0)
-		} else if state == "active" {
+		case "active":
 			testSummaryHelper(t, state, summary[state], 1.0)
-		} else {
+		default:
 			testSummaryHelper(t, state, summary[state], 0.0)
 		}
 	}

collector/zfs_linux.go

@@ -435,5 +435,5 @@ type zfsSysctl string
 
 func (s zfsSysctl) metricName() string {
 	parts := strings.Split(string(s), ".")
-	return strings.Replace(parts[len(parts)-1], "-", "_", -1)
+	return strings.ReplaceAll(parts[len(parts)-1], "-", "_")
 }