utils: share the include/exclude regexp flag handling (#2737)

Signed-off-by: Jan-Otto Kröpke <mail@jkroepke.de>

internal/collector/printer/printer.go

@@ -29,6 +29,7 @@ import (
 	"github.com/prometheus-community/windows_exporter/internal/metriccache"
 	"github.com/prometheus-community/windows_exporter/internal/mi"
 	"github.com/prometheus-community/windows_exporter/internal/types"
+	"github.com/prometheus-community/windows_exporter/internal/utils"
 	"github.com/prometheus/client_golang/prometheus"
 	"golang.org/x/sys/windows"
 )
@@ -112,33 +113,17 @@ func NewWithFlags(app *kingpin.Application) *Collector {
 		config: ConfigDefaults,
 	}
 
-	var printerInclude, printerExclude string
-
-	app.Flag(
+	utils.RegexpFlag(app,
 		"collector.printer.include",
 		"Regular expression to match printers to collect metrics for",
-	).Default(".+").StringVar(&printerInclude)
+		".+", &c.config.PrinterInclude,
+	)
 
-	app.Flag(
+	utils.RegexpFlag(app,
 		"collector.printer.exclude",
 		"Regular expression to match printers to exclude",
-	).Default("").StringVar(&printerExclude)
-
-	app.Action(func(*kingpin.ParseContext) error {
-		var err error
-
-		c.config.PrinterInclude, err = regexp.Compile(fmt.Sprintf("^(?:%s)$", printerInclude))
-		if err != nil {
-			return fmt.Errorf("collector.printer.include: %w", err)
-		}
-
-		c.config.PrinterExclude, err = regexp.Compile(fmt.Sprintf("^(?:%s)$", printerExclude))
-		if err != nil {
-			return fmt.Errorf("collector.printer.exclude: %w", err)
-		}
-
-		return nil
-	})
+		"", &c.config.PrinterExclude,
+	)
 
 	return c
 }

internal/collector/printer/printer_test.go

@@ -22,7 +22,6 @@ import (
 	"testing"
 	"time"
 
-	"github.com/alecthomas/kingpin/v2"
 	"github.com/prometheus-community/windows_exporter/internal/collector/printer"
 	"github.com/prometheus-community/windows_exporter/internal/utils/testutils"
 	"github.com/prometheus/client_golang/prometheus"
@@ -31,12 +30,7 @@ import (
 )
 
 func BenchmarkCollector(b *testing.B) {
-	// Whitelist is not set in testing context (kingpin flags not parsed), causing the collector to skip all printers.
-	printersInclude := ".+"
-
-	testutils.FuncBenchmarkCollector(b, "printer", printer.NewWithFlags, func(app *kingpin.Application) {
-		app.GetFlag("collector.printer.include").StringVar(&printersInclude)
-	})
+	testutils.FuncBenchmarkCollector(b, "printer", printer.NewWithFlags)
 }
 
 func TestCollector(t *testing.T) {