Add collector names into usage of collector flag

pkg/cmd/root.go

@@ -3,7 +3,9 @@
 package cmd
 
 import (
+	"fmt"
 	"os"
+	"strings"
 
 	log "github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
@@ -115,6 +117,12 @@ func init() { //nolint:funlen // Allow this to get a little long
 		"collector",
 		"s",
 		defaultCollectorNames,
-		"the collectors you wish to run default is all",
+		fmt.Sprintf(
+			"the collectors you wish to run (case-insensitive):\n"+
+				"\trequired collectors: %s (will be automatically added)\n"+
+				"\toptional collectors: %s",
+			strings.Join(runner.RequiredCollectorNames, ", "),
+			strings.Join(runner.OptionalCollectorNames, ", "),
+		),
 	)
 }

pkg/runner/collector_selector.go

@@ -11,14 +11,14 @@ import (
 )
 
 var (
-	optionalCollectorNames []string
-	requiredCollectorNames []string
+	OptionalCollectorNames []string
+	RequiredCollectorNames []string
 	All                    string = "all"
 )
 
 func init() {
-	optionalCollectorNames = []string{collectors.DPLLCollectorName, collectors.GPSCollectorName}
-	requiredCollectorNames = []string{collectors.DevInfoCollectorName}
+	OptionalCollectorNames = []string{collectors.DPLLCollectorName, collectors.GPSCollectorName}
+	RequiredCollectorNames = []string{collectors.DevInfoCollectorName}
 }
 
 func isIn(name string, arr []string) bool {
@@ -45,16 +45,16 @@ func removeDuplicates(arr []string) []string {
 // are returned
 func GetCollectorsToRun(selectedCollectors []string) []string {
 	collectorNames := make([]string, 0)
-	collectorNames = append(collectorNames, requiredCollectorNames...)
+	collectorNames = append(collectorNames, RequiredCollectorNames...)
 	for _, name := range selectedCollectors {
 		switch {
 		case strings.EqualFold(name, "all"):
-			collectorNames = append(collectorNames, optionalCollectorNames...)
+			collectorNames = append(collectorNames, OptionalCollectorNames...)
 			collectorNames = removeDuplicates(collectorNames)
 			return collectorNames
 		case isIn(name, collectorNames):
 			continue
-		case isIn(name, optionalCollectorNames):
+		case isIn(name, OptionalCollectorNames):
 			collectorNames = append(collectorNames, name)
 		default:
 			log.Errorf("Unknown collector %s. Ignored", name)