fix: Support scraping pods metrics that is still in scheduling status and has no assigned node

README.md

@@ -250,7 +250,7 @@ The downside of using an auto-sharded setup comes from the rollout strategy supp
 
 For pod metrics, they can be sharded per node with the following flag:
 
-* `--node`
+* `--node=$(NODE_NAME)`
 
 Each kube-state-metrics pod uses FieldSelector (spec.nodeName) to watch/list pod metrics only on the same node.
 
@@ -276,6 +276,22 @@ spec:
               fieldPath: spec.nodeName
 ```
 
+To track metrics for unassigned pods, you need to add an additional deployment and set `--node=""`, as shown in the following example:
+
+```
+apiVersion: apps/v1
+kind: Deployment
+spec:
+  template:
+    spec:
+      containers:
+      - image: registry.k8s.io/kube-state-metrics/kube-state-metrics:IMAGE_TAG
+        name: kube-state-metrics
+        args:
+        - --resources=pods
+        - --node=""
+```
+
 Other metrics can be sharded via [Horizontal sharding](#horizontal-sharding).
 
 ### Setup

examples/daemonsetsharding/deployment-no-node-pods.yaml

@@ -0,0 +1,58 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  labels:
+    app.kubernetes.io/component: exporter
+    app.kubernetes.io/name: kube-state-metrics-pods
+    app.kubernetes.io/version: 2.10.0
+  name: kube-state-metrics-pods
+  namespace: kube-system
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: kube-state-metrics
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/component: exporter
+        app.kubernetes.io/name: kube-state-metrics
+        app.kubernetes.io/version: 2.10.0
+    spec:
+      automountServiceAccountToken: true
+      containers:
+      - args:
+        - --resources=pods
+        - --node=""
+        image: registry.k8s.io/kube-state-metrics/kube-state-metrics:v2.10.0
+        livenessProbe:
+          httpGet:
+            path: /healthz
+            port: 8080
+          initialDelaySeconds: 5
+          timeoutSeconds: 5
+        name: kube-state-metrics
+        ports:
+        - containerPort: 8080
+          name: http-metrics
+        - containerPort: 8081
+          name: telemetry
+        readinessProbe:
+          httpGet:
+            path: /
+            port: 8081
+          initialDelaySeconds: 5
+          timeoutSeconds: 5
+        securityContext:
+          allowPrivilegeEscalation: false
+          capabilities:
+            drop:
+            - ALL
+          readOnlyRootFilesystem: true
+          runAsNonRoot: true
+          runAsUser: 65534
+          seccompProfile:
+            type: RuntimeDefault
+      nodeSelector:
+        kubernetes.io/os: linux
+      serviceAccountName: kube-state-metrics

jsonnet/kube-state-metrics/kube-state-metrics.libsonnet

@@ -373,6 +373,30 @@
         },
       ),
 
+    deploymentNoNodePods:
+      local c = ksm.deployment.spec.template.spec.containers[0] {
+        args: [
+          '--resources=pods',
+          '--node=""',
+        ],
+      };
+      local shardksmname = ksm.name + "-pods";
+      std.mergePatch(ksm.deployment,
+        {
+          metadata: {
+            name: shardksmname,
+            labels: {'app.kubernetes.io/name': shardksmname}
+          },
+          spec: {
+            template: {
+              spec: {
+                containers: [c],
+              },
+            },
+          },
+        },
+      ),
+
     daemonset:
       // extending the default container from above
       local c0 = ksm.deployment.spec.template.spec.containers[0] {

pkg/options/options.go

@@ -73,6 +73,7 @@ func NewOptions() *Options {
 		MetricAllowlist:      MetricSet{},
 		MetricDenylist:       MetricSet{},
 		MetricOptInList:      MetricSet{},
+		Node:                 NodeType{},
 		AnnotationsAllowList: LabelsAllowList{},
 		LabelsAllowList:      LabelsAllowList{},
 	}
@@ -136,7 +137,7 @@ func (o *Options) AddFlags(cmd *cobra.Command) {
 	o.cmd.Flags().StringVar(&o.TLSConfig, "tls-config", "", "Path to the TLS configuration file")
 	o.cmd.Flags().StringVar(&o.TelemetryHost, "telemetry-host", "::", `Host to expose kube-state-metrics self metrics on.`)
 	o.cmd.Flags().StringVar(&o.Config, "config", "", "Path to the kube-state-metrics options config file")
-	o.cmd.Flags().StringVar((*string)(&o.Node), "node", "", "Name of the node that contains the kube-state-metrics pod. Most likely it should be passed via the downward API. This is used for daemonset sharding. Only available for resources (pod metrics) that support spec.nodeName fieldSelector. This is experimental.")
+	o.cmd.Flags().Var(&o.Node, "node", "Name of the node that contains the kube-state-metrics pod. Most likely it should be passed via the downward API. This is used for daemonset sharding. Only available for resources (pod metrics) that support spec.nodeName fieldSelector. This is experimental.")
 	o.cmd.Flags().Var(&o.AnnotationsAllowList, "metric-annotations-allowlist", "Comma-separated list of Kubernetes annotations keys that will be used in the resource' labels metric. By default the annotations metrics are not exposed. To include them, provide a list of resource names in their plural form and Kubernetes annotation keys you would like to allow for them (Example: '=namespaces=[kubernetes.io/team,...],pods=[kubernetes.io/team],...)'. A single '*' can be provided per resource instead to allow any annotations, but that has severe performance implications (Example: '=pods=[*]').")
 	o.cmd.Flags().Var(&o.LabelsAllowList, "metric-labels-allowlist", "Comma-separated list of additional Kubernetes label keys that will be used in the resource' labels metric. By default the labels metrics are not exposed. To include them, provide a list of resource names in their plural form and Kubernetes label keys you would like to allow for them (Example: '=namespaces=[k8s-label-1,k8s-label-n,...],pods=[app],...)'. A single '*' can be provided per resource instead to allow any labels, but that has severe performance implications (Example: '=pods=[*]'). Additionally, an asterisk (*) can be provided as a key, which will resolve to all resources, i.e., assuming '--resources=deployments,pods', '=*=[*]' will resolve to '=deployments=[*],pods=[*]'.")
 	o.cmd.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.")
@@ -161,7 +162,7 @@ func (o *Options) Usage() {
 // Validate validates arguments
 func (o *Options) Validate() error {
 	shardableResource := "pods"
-	if o.Node == "" {
+	if o.Node.String() == "" {
 		return nil
 	}
 	for _, x := range o.Resources.AsSlice() {

pkg/options/types.go

@@ -18,6 +18,7 @@ package options
 
 import (
 	"errors"
+	"regexp"
 	"sort"
 	"strings"
 
@@ -105,14 +106,56 @@ func (r *ResourceSet) Type() string {
 }
 
 // NodeType represents a nodeName to query from.
-type NodeType string
+type NodeType map[string]struct{}
+
+// Set converts a comma-separated string of nodename into a slice and appends it to the NodeList
+func (n *NodeType) Set(value string) error {
+	s := *n
+	cols := strings.Split(value, ",")
+	for _, col := range cols {
+		col = strings.TrimSpace(col)
+		if len(col) != 0 {
+			s[col] = struct{}{}
+		}
+	}
+	return nil
+}
+
+// AsSlice returns the LabelsAllowList in the form of plain string slice.
+func (n NodeType) AsSlice() []string {
+	cols := make([]string, 0, len(n))
+	for col := range n {
+		cols = append(cols, col)
+	}
+	return cols
+}
+
+func (n NodeType) String() string {
+	return strings.Join(n.AsSlice(), ",")
+}
+
+// Type returns a descriptive string about the NodeList type.
+func (n *NodeType) Type() string {
+	return "string"
+}
 
 // GetNodeFieldSelector returns a nodename field selector.
 func (n *NodeType) GetNodeFieldSelector() string {
-	if string(*n) != "" {
-		return fields.OneTermEqualSelector("spec.nodeName", string(*n)).String()
+	if nil == n || len(*n) == 0 {
+		klog.InfoS("Using node type is nil")
+		return EmptyFieldSelector()
 	}
-	return EmptyFieldSelector()
+	pattern := "[^a-zA-Z0-9_,-]+"
+	re := regexp.MustCompile(pattern)
+	result := re.ReplaceAllString(n.String(), "")
+	klog.InfoS("Using node type", "node", result)
+	return fields.OneTermEqualSelector("spec.nodeName", result).String()
+
+}
+
+// NodeValue represents a nodeName to query from.
+type NodeValue interface {
+	GetNodeFieldSelector() string
 }
 
 // EmptyFieldSelector returns an empty field selector.

pkg/options/types_test.go

@@ -162,13 +162,30 @@ func TestNodeFieldSelector(t *testing.T) {
 		Wanted string
 	}{
 		{
-			Desc:   "empty node name",
-			Node:   "",
+			Desc:   "with node name",
 			Wanted: "",
 		},
 		{
 			Desc:   "with node name",
-			Node:   "k8s-node-1",
+			Node:   nil,
+			Wanted: "",
+		},
+		{
+			Desc: "empty node name",
+			Node: NodeType(
+				map[string]struct{}{
+					"": {},
+				},
+			),
+			Wanted: "spec.nodeName=",
+		},
+		{
+			Desc: "with node name",
+			Node: NodeType(
+				map[string]struct{}{
+					"k8s-node-1": {},
+				},
+			),
 			Wanted: "spec.nodeName=k8s-node-1",
 		},
 	}
@@ -194,43 +211,67 @@ func TestMergeFieldSelectors(t *testing.T) {
 			Desc:             "empty DeniedNamespaces",
 			Namespaces:       NamespaceList{"default", "kube-system"},
 			DeniedNamespaces: NamespaceList{},
-			Node:             "",
-			Wanted:           "",
+			Node: NodeType(
+				map[string]struct{}{
+					"": {},
+				},
+			),
+			Wanted: "spec.nodeName=",
 		},
 		{
 			Desc:             "all DeniedNamespaces",
 			Namespaces:       DefaultNamespaces,
 			DeniedNamespaces: NamespaceList{"some-system"},
-			Node:             "",
-			Wanted:           "metadata.namespace!=some-system",
+			Node: NodeType(
+				map[string]struct{}{
+					"": {},
+				},
+			),
+			Wanted: "metadata.namespace!=some-system,spec.nodeName=",
 		},
 		{
 			Desc:             "general case",
 			Namespaces:       DefaultNamespaces,
 			DeniedNamespaces: NamespaceList{"case1-system", "case2-system"},
-			Node:             "",
-			Wanted:           "metadata.namespace!=case1-system,metadata.namespace!=case2-system",
+			Node: NodeType(
+				map[string]struct{}{
+					"": {},
+				},
+			),
+			Wanted: "metadata.namespace!=case1-system,metadata.namespace!=case2-system,spec.nodeName=",
 		},
 		{
 			Desc:             "empty DeniedNamespaces",
 			Namespaces:       NamespaceList{"default", "kube-system"},
 			DeniedNamespaces: NamespaceList{},
-			Node:             "k8s-node-1",
-			Wanted:           "spec.nodeName=k8s-node-1",
+			Node: NodeType(
+				map[string]struct{}{
+					"k8s-node-1": {},
+				},
+			),
+			Wanted: "spec.nodeName=k8s-node-1",
 		},
 		{
 			Desc:             "all DeniedNamespaces",
 			Namespaces:       DefaultNamespaces,
 			DeniedNamespaces: NamespaceList{"some-system"},
-			Node:             "k8s-node-1",
-			Wanted:           "metadata.namespace!=some-system,spec.nodeName=k8s-node-1",
+			Node: NodeType(
+				map[string]struct{}{
+					"k8s-node-1": {},
+				},
+			),
+			Wanted: "metadata.namespace!=some-system,spec.nodeName=k8s-node-1",
 		},
 		{
 			Desc:             "general case",
 			Namespaces:       DefaultNamespaces,
 			DeniedNamespaces: NamespaceList{"case1-system", "case2-system"},
-			Node:             "k8s-node-1",
-			Wanted:           "metadata.namespace!=case1-system,metadata.namespace!=case2-system,spec.nodeName=k8s-node-1",
+			Node: NodeType(
+				map[string]struct{}{
+					"k8s-node-1": {},
+				},
+			),
+			Wanted: "metadata.namespace!=case1-system,metadata.namespace!=case2-system,spec.nodeName=k8s-node-1",
 		},
 	}