Refactoring

docs/cli-arguments.md

@@ -46,7 +46,7 @@ Usage of ./kube-state-metrics:
       --metric-opt-in-list string                  Comma-separated list of metrics which are opt-in and not enabled by default. This is in addition to the metric allow- and denylists
       --namespaces string                          Comma-separated list of namespaces to be enabled. Defaults to ""
       --namespaces-denylist string                 Comma-separated list of namespaces not to be enabled. If namespaces and namespaces-denylist are both set, only namespaces that are excluded in namespaces-denylist will be used.
-      --nodename string                            Set spec.nodeName=nodename when watching resources. Only available for resources which support nodeName filter.
+      --nodename string                            Name of the node that contains the kube-state-metrics pod, only available for resources (pod metrics) that support spec.nodeName fieldSelector. Each kube-state-metrics pod will only exposes metrics related to this node.
       --one_output                                 If true, only write logs to their native severity level (vs also writing to each lower severity level; no effect when -logtostderr=true)
       --pod string                                 Name of the pod that contains the kube-state-metrics container. When set, it is expected that --pod and --pod-namespace are both set. Most likely this should be passed via the downward API. This is used for auto-detecting sharding. If set, this has preference over statically configured sharding. This is experimental, it may be removed without notice.
       --pod-namespace string                       Name of the namespace of the pod specified by --pod. When set, it is expected that --pod and --pod-namespace are both set. Most likely this should be passed via the downward API. This is used for auto-detecting sharding. If set, this has preference over statically configured sharding. This is experimental, it may be removed without notice.

internal/store/builder.go

@@ -58,10 +58,11 @@ var _ ksmtypes.BuilderInterface = &Builder{}
 // Builder helps to build store. It follows the builder pattern
 // (https://en.wikipedia.org/wiki/Builder_pattern).
 type Builder struct {
-	kubeClient                    clientset.Interface
-	customResourceClients         map[string]interface{}
-	vpaClient                     vpaclientset.Interface
-	namespaces                    options.NamespaceList
+	kubeClient            clientset.Interface
+	customResourceClients map[string]interface{}
+	vpaClient             vpaclientset.Interface
+	namespaces            options.NamespaceList
+	// namespaceFilter is inside fieldSelectorFilter
 	fieldSelectorFilter           string
 	ctx                           context.Context
 	enabledResources              []string
@@ -116,17 +117,9 @@ func (b *Builder) WithNamespaces(n options.NamespaceList) {
 	b.namespaces = n
 }
 
-// MergeFieldSelector merges multiple fieldSelectors using AND operator.
-func (b *Builder) MergeFieldSelector(selectors []string) (string, error) {
-	var err error
-	merged := options.EmptyFieldSelector()
-	for _, s := range selectors {
-		merged, err = options.MergeFieldSelector(merged, s)
-		if err != nil {
-			return "", err
-		}
-	}
-	return merged, nil
+// MergeFieldSelectors merges multiple fieldSelectors using AND operator.
+func (b *Builder) MergeFieldSelectors(selectors []string) (string, error) {
+	return options.MergeFieldSelectors(selectors)
 }
 
 // WithSharding sets the shard and totalShards property of a Builder.
@@ -485,7 +478,7 @@ func (b *Builder) buildStores(
 			composedMetricGenFuncs,
 		)
 		if b.fieldSelectorFilter != "" {
-			klog.Infof("FieldSelector is used ", b.fieldSelectorFilter)
+			klog.Infof("FieldSelector is used %s", b.fieldSelectorFilter)
 		}
 		listWatcher := listWatchFunc(b.kubeClient, v1.NamespaceAll, b.fieldSelectorFilter)
 		b.startReflector(expectedType, store, listWatcher, useAPIServerCache)
@@ -499,7 +492,7 @@ func (b *Builder) buildStores(
 			composedMetricGenFuncs,
 		)
 		if b.fieldSelectorFilter != "" {
-			klog.Infof("FieldSelector is used ", b.fieldSelectorFilter)
+			klog.Infof("FieldSelector is used %s", b.fieldSelectorFilter)
 		}
 		listWatcher := listWatchFunc(b.kubeClient, ns, b.fieldSelectorFilter)
 		b.startReflector(expectedType, store, listWatcher, useAPIServerCache)
@@ -532,7 +525,7 @@ func (b *Builder) buildCustomResourceStores(resourceName string,
 			composedMetricGenFuncs,
 		)
 		if b.fieldSelectorFilter != "" {
-			klog.Infof("FieldSelector is used ", b.fieldSelectorFilter)
+			klog.Infof("FieldSelector is used %s", b.fieldSelectorFilter)
 		}
 		listWatcher := listWatchFunc(customResourceClient, v1.NamespaceAll, b.fieldSelectorFilter)
 		b.startReflector(expectedType, store, listWatcher, useAPIServerCache)
@@ -545,7 +538,7 @@ func (b *Builder) buildCustomResourceStores(resourceName string,
 			familyHeaders,
 			composedMetricGenFuncs,
 		)
-		klog.Infof("FieldSelector is used ", b.fieldSelectorFilter)
+		klog.Infof("FieldSelector is used %s", b.fieldSelectorFilter)
 		listWatcher := listWatchFunc(customResourceClient, ns, b.fieldSelectorFilter)
 		b.startReflector(expectedType, store, listWatcher, useAPIServerCache)
 		stores = append(stores, store)

main.go

@@ -34,19 +34,6 @@ import (
 	"k8s.io/kube-state-metrics/v2/pkg/options"
 )
 
-func validate(opts *options.Options) error {
-	shardableResource := "pods"
-	if opts.NodeName == "" {
-		return nil
-	}
-	for _, x := range opts.Resources.AsSlice() {
-		if x != shardableResource {
-			return fmt.Errorf("Resource %s can't be sharding by field selector nodeName", x)
-		}
-	}
-	return nil
-}
-
 func main() {
 	opts := options.NewOptions()
 	opts.AddFlags()
@@ -66,7 +53,7 @@ func main() {
 		os.Exit(0)
 	}
 
-	if err := validate(opts); err != nil {
+	if err := opts.Validate(); err != nil {
 		klog.ErrorS(err, "Validating options error")
 		klog.FlushAndExit(klog.ExitFlushTimeout, 1)
 	}

pkg/app/server.go

@@ -107,7 +107,7 @@ func RunKubeStateMetrics(ctx context.Context, opts *options.Options, factories .
 	namespaces := opts.Namespaces.GetNamespaces()
 	nsFieldSelector := namespaces.GetExcludeNSFieldSelector(opts.NamespacesDenylist)
 	nodeNameFieldSelector := opts.NodeName.GetNodeNameFieldSelector()
-	merged, err := storeBuilder.MergeFieldSelector([]string{nsFieldSelector, nodeNameFieldSelector})
+	merged, err := storeBuilder.MergeFieldSelectors([]string{nsFieldSelector, nodeNameFieldSelector})
 	if err != nil {
 		return err
 	}

pkg/options/options.go

@@ -104,7 +104,7 @@ func (o *Options) AddFlags() {
 	o.flags.Var(&o.Resources, "resources", fmt.Sprintf("Comma-separated list of Resources to be enabled. Defaults to %q", &DefaultResources))
 	o.flags.Var(&o.Namespaces, "namespaces", fmt.Sprintf("Comma-separated list of namespaces to be enabled. Defaults to %q", &DefaultNamespaces))
 	o.flags.Var(&o.NamespacesDenylist, "namespaces-denylist", "Comma-separated list of namespaces not to be enabled. If namespaces and namespaces-denylist are both set, only namespaces that are excluded in namespaces-denylist will be used.")
-	o.flags.StringVar((*string)(&o.NodeName), "nodename", "", "Set spec.nodeName=nodename when watching resources. Only available for resources which support nodeName filter.")
+	o.flags.StringVar((*string)(&o.NodeName), "nodename", "", "Name of the node that contains the kube-state-metrics pod, only available for resources (pod metrics) that support spec.nodeName fieldSelector. Each kube-state-metrics pod will only exposes metrics related to this node.")
 	o.flags.Var(&o.MetricAllowlist, "metric-allowlist", "Comma-separated list of metrics to be exposed. This list comprises of exact metric names and/or regex patterns. The allowlist and denylist are mutually exclusive.")
 	o.flags.Var(&o.MetricDenylist, "metric-denylist", "Comma-separated list of metrics not to be enabled. This list comprises of exact metric names and/or regex patterns. The allowlist and denylist are mutually exclusive.")
 	o.flags.Var(&o.MetricOptInList, "metric-opt-in-list", "Comma-separated list of metrics which are opt-in and not enabled by default. This is in addition to the metric allow- and denylists")
@@ -134,3 +134,17 @@ func (o *Options) Parse() error {
 func (o *Options) Usage() {
 	o.flags.Usage()
 }
+
+// Validate validates arguments
+func (o *Options) Validate() error {
+	shardableResource := "pods"
+	if o.NodeName == "" {
+		return nil
+	}
+	for _, x := range o.Resources.AsSlice() {
+		if x != shardableResource {
+			return fmt.Errorf("Resource %s can't be sharding by field selector spec.nodeName", x)
+		}
+	}
+	return nil
+}

pkg/options/types.go

@@ -120,8 +120,21 @@ func EmptyFieldSelector() string {
 	return fields.Nothing().String()
 }
 
-// MergeFieldSelector returns AND of two field selectors.
-func MergeFieldSelector(s1 string, s2 string) (string, error) {
+// MergeFieldSelectors returns AND of a list of field selectors.
+func MergeFieldSelectors(selectors []string) (string, error) {
+	var err error
+	merged := EmptyFieldSelector()
+	for _, s := range selectors {
+		merged, err = MergeTwoFieldSelectors(merged, s)
+		if err != nil {
+			return "", err
+		}
+	}
+	return merged, nil
+}
+
+// MergeTwoFieldSelectors returns AND of two field selectors.
+func MergeTwoFieldSelectors(s1 string, s2 string) (string, error) {
 	selector1, err := fields.ParseSelector(s1)
 	if err != nil {
 		return EmptyFieldSelector(), err

pkg/options/types_test.go

@@ -182,7 +182,7 @@ func TestNodeNameFieldSelector(t *testing.T) {
 	}
 }
 
-func TestMergeFieldSelector(t *testing.T) {
+func TestMergeFieldSelectors(t *testing.T) {
 	tests := []struct {
 		Desc             string
 		Namespaces       NamespaceList
@@ -239,7 +239,7 @@ func TestMergeFieldSelector(t *testing.T) {
 		deniedNS := test.DeniedNamespaces
 		selector1 := ns.GetExcludeNSFieldSelector(deniedNS)
 		selector2 := test.NodeName.GetNodeNameFieldSelector()
-		actual, err := MergeFieldSelector(selector1, selector2)
+		actual, err := MergeFieldSelectors([]string{selector1, selector2})
 		if err != nil {
 			t.Errorf("Test error for Desc: %s. Can't merge field selector %v.", test.Desc, err)
 		}