Golangci lint fixes (#195)

* Add golangci-lin as make target
* Fix: could omit type ... from declaration; it will be inferred from the right-hand side (staticcheck)
* Fix func intArrayContains is unused (unused)
* Fix: could use strings.ReplaceAll instead (staticcheck)
* Fix: could expand call to math.Pow (staticcheck)
* Fix: could use tagged switch on `...` (staticcheck)
* Fix: Error return value of `...` is not checked (errcheck)
* Fix: ineffectual assignment to err (ineffassign)
* Fix: There is no need to wait for command completion
* Add cpustat, diskstat and schedstat config
* Use slices to exclude metrics
* Replaced stringArrayContains by slices.Contains
* Replace m[k]=v loop with maps.Copy
* Use module slices from the standard library. Remove use of golang.org/x/exp/slices
* Use SplitSeq and max to modernize code

collectors/nfsiostatMetric.go

@@ -12,6 +12,7 @@ import (
 	"fmt"
 	"os"
 	"regexp"
+	"slices"
 	"strconv"
 	"strings"
 	"time"
@@ -71,7 +72,7 @@ func (m *NfsIOStatCollector) readNfsiostats() map[string]map[string]int64 {
 		// Is this a device line with mount point, remote target and NFS version?
 		dev := resolve_regex_fields(l, deviceRegex)
 		if len(dev) > 0 {
-			if _, ok := stringArrayContains(m.config.ExcludeFilesystem, dev[m.key]); !ok {
+			if !slices.Contains(m.config.ExcludeFilesystem, dev[m.key]) {
 				current = dev
 				if len(current["version"]) == 0 {
 					current["version"] = "3"
@@ -85,7 +86,7 @@ func (m *NfsIOStatCollector) readNfsiostats() map[string]map[string]int64 {
 			if len(bytes) > 0 {
 				data[current[m.key]] = make(map[string]int64)
 				for name, sval := range bytes {
-					if _, ok := stringArrayContains(m.config.ExcludeMetrics, name); !ok {
+					if !slices.Contains(m.config.ExcludeMetrics, name) {
 						val, err := strconv.ParseInt(sval, 10, 64)
 						if err == nil {
 							data[current[m.key]][name] = val
@@ -102,7 +103,9 @@ func (m *NfsIOStatCollector) readNfsiostats() map[string]map[string]int64 {
 func (m *NfsIOStatCollector) Init(config json.RawMessage) error {
 	var err error = nil
 	m.name = "NfsIOStatCollector"
-	m.setup()
+	if err := m.setup(); err != nil {
+		return fmt.Errorf("%s Init(): setup() call failed: %w", m.name, err)
+	}
 	m.parallel = true
 	m.meta = map[string]string{"source": m.name, "group": "NFS", "unit": "bytes"}
 	m.tags = map[string]string{"type": "node"}