feat: add label selectors to listing tools

This PR introduces the ability to filter Kubernetes resources by label using a labelSelector parameter for the following tools:

 * pods_list
 * pods_list_in_namespace
 * resources_list

This enhancement allows users to retrieve a more specific set of resources based on their labels, improving the flexibility and utility of these tools.

The labelSelector parameter accepts standard Kubernetes label selector syntax, such as app=myapp,env=prod or app in (myapp,yourapp).

Signed-off-by: Eran Cohen <[email protected]>

Author: eranco74

README.md

@@ -261,7 +261,9 @@ Get a Kubernetes Pod in the current or provided namespace with the provided name
 
 List all the Kubernetes pods in the current cluster from all namespaces
 
-**Parameters:** None
+**Parameters:**
+- `labelSelector` (`string`, optional)
+  - Kubernetes label selector (e.g., 'app=myapp,env=prod' or 'app in (myapp,yourapp)'). Use this option to filter the pods by label
 
 ### `pods_list_in_namespace`
 
@@ -270,6 +272,8 @@ List all the Kubernetes pods in the specified namespace in the current cluster
 **Parameters:**
 - `namespace` (`string`, required)
   - Namespace to list pods from
+- `labelSelector` (`string`, optional)
+  - Kubernetes label selector (e.g., 'app=myapp,env=prod' or 'app in (myapp,yourapp)'). Use this option to filter the pods by label
 
 ### `pods_log`
 
@@ -363,6 +367,8 @@ List Kubernetes resources and objects in the current cluster
   - Namespace to retrieve the namespaced resources from
   - Ignored for cluster-scoped resources
   - Lists resources from all namespaces if not provided
+- `labelSelector` (`string`, optional)
+  - Kubernetes label selector (e.g., 'app=myapp,env=prod' or 'app in (myapp,yourapp)'). Use this option to filter the pods by label.
 
 ## 🧑‍💻 Development <a id="development"></a>
 

pkg/kubernetes/events.go

@@ -12,7 +12,7 @@ import (
 func (k *Kubernetes) EventsList(ctx context.Context, namespace string) (string, error) {
 	unstructuredList, err := k.resourcesList(ctx, &schema.GroupVersionKind{
 		Group: "", Version: "v1", Kind: "Event",
-	}, namespace)
+	}, namespace, "")
 	if err != nil {
 		return "", err
 	}

pkg/kubernetes/pods.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+
 	"github.com/manusa/kubernetes-mcp-server/pkg/version"
 	v1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -17,16 +18,16 @@ import (
 	"k8s.io/client-go/tools/remotecommand"
 )
 
-func (k *Kubernetes) PodsListInAllNamespaces(ctx context.Context) (string, error) {
+func (k *Kubernetes) PodsListInAllNamespaces(ctx context.Context, labelSelector string) (string, error) {
 	return k.ResourcesList(ctx, &schema.GroupVersionKind{
 		Group: "", Version: "v1", Kind: "Pod",
-	}, "")
+	}, "", labelSelector)
 }
 
-func (k *Kubernetes) PodsListInNamespace(ctx context.Context, namespace string) (string, error) {
+func (k *Kubernetes) PodsListInNamespace(ctx context.Context, namespace string, labelSelector string) (string, error) {
 	return k.ResourcesList(ctx, &schema.GroupVersionKind{
 		Group: "", Version: "v1", Kind: "Pod",
-	}, namespace)
+	}, namespace, labelSelector)
 }
 
 func (k *Kubernetes) PodsGet(ctx context.Context, namespace, name string) (string, error) {

pkg/kubernetes/resources.go

@@ -2,14 +2,15 @@ package kubernetes
 
 import (
 	"context"
+	"regexp"
+	"strings"
+
 	"github.com/manusa/kubernetes-mcp-server/pkg/version"
 	authv1 "k8s.io/api/authorization/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/util/yaml"
-	"regexp"
-	"strings"
 )
 
 const (
@@ -19,8 +20,12 @@ const (
 	AppKubernetesPartOf    = "app.kubernetes.io/part-of"
 )
 
-func (k *Kubernetes) ResourcesList(ctx context.Context, gvk *schema.GroupVersionKind, namespace string) (string, error) {
-	rl, err := k.resourcesList(ctx, gvk, namespace)
+func (k *Kubernetes) ResourcesList(ctx context.Context, gvk *schema.GroupVersionKind, namespace string, labelSelector ...string) (string, error) {
+	var selector string
+	if len(labelSelector) > 0 {
+		selector = labelSelector[0]
+	}
+	rl, err := k.resourcesList(ctx, gvk, namespace, selector)
 	if err != nil {
 		return "", err
 	}
@@ -69,7 +74,7 @@ func (k *Kubernetes) ResourcesDelete(ctx context.Context, gvk *schema.GroupVersi
 	return k.dynamicClient.Resource(*gvr).Namespace(namespace).Delete(ctx, name, metav1.DeleteOptions{})
 }
 
-func (k *Kubernetes) resourcesList(ctx context.Context, gvk *schema.GroupVersionKind, namespace string) (*unstructured.UnstructuredList, error) {
+func (k *Kubernetes) resourcesList(ctx context.Context, gvk *schema.GroupVersionKind, namespace string, labelSelector string) (*unstructured.UnstructuredList, error) {
 	gvr, err := k.resourceFor(gvk)
 	if err != nil {
 		return nil, err
@@ -79,7 +84,9 @@ func (k *Kubernetes) resourcesList(ctx context.Context, gvk *schema.GroupVersion
 	if isNamespaced && !k.canIUse(ctx, gvr, namespace, "list") && namespace == "" {
 		namespace = k.configuredNamespace()
 	}
-	return k.dynamicClient.Resource(*gvr).Namespace(namespace).List(ctx, metav1.ListOptions{})
+	return k.dynamicClient.Resource(*gvr).Namespace(namespace).List(ctx, metav1.ListOptions{
+		LabelSelector: labelSelector,
+	})
 }
 
 func (k *Kubernetes) resourcesCreateOrUpdate(ctx context.Context, resources []*unstructured.Unstructured) (string, error) {

pkg/mcp/common_test.go

@@ -298,6 +298,9 @@ func (c *mcpContext) crdWaitUntilReady(name string) {
 	watcher, err := c.newApiExtensionsClient().CustomResourceDefinitions().Watch(c.ctx, metav1.ListOptions{
 		FieldSelector: "metadata.name=" + name,
 	})
+	if err != nil {
+		panic(fmt.Errorf("failed to watch CRD %v", err))
+	}
 	_, err = toolswatch.UntilWithoutRetry(c.ctx, watcher, func(event watch.Event) (bool, error) {
 		for _, c := range event.Object.(*apiextensionsv1spec.CustomResourceDefinition).Status.Conditions {
 			if c.Type == apiextensionsv1spec.Established && c.Status == apiextensionsv1spec.ConditionTrue {
@@ -347,17 +350,45 @@ func createTestData(ctx context.Context) {
 	_, _ = kubernetesAdmin.CoreV1().Namespaces().
 		Create(ctx, &corev1.Namespace{ObjectMeta: metav1.ObjectMeta{Name: "ns-to-delete"}}, metav1.CreateOptions{})
 	_, _ = kubernetesAdmin.CoreV1().Pods("default").Create(ctx, &corev1.Pod{
-		ObjectMeta: metav1.ObjectMeta{Name: "a-pod-in-default"},
-		Spec:       corev1.PodSpec{Containers: []corev1.Container{{Name: "nginx", Image: "nginx"}}},
+		ObjectMeta: metav1.ObjectMeta{
+			Name:   "a-pod-in-default",
+			Labels: map[string]string{"app": "nginx"},
+		},
+		Spec: corev1.PodSpec{
+			Containers: []corev1.Container{
+				{
+					Name:  "nginx",
+					Image: "nginx",
+				},
+			},
+		},
 	}, metav1.CreateOptions{})
 	// Pods for listing
 	_, _ = kubernetesAdmin.CoreV1().Pods("ns-1").Create(ctx, &corev1.Pod{
-		ObjectMeta: metav1.ObjectMeta{Name: "a-pod-in-ns-1"},
-		Spec:       corev1.PodSpec{Containers: []corev1.Container{{Name: "nginx", Image: "nginx"}}},
+		ObjectMeta: metav1.ObjectMeta{
+			Name: "a-pod-in-ns-1",
+		},
+		Spec: corev1.PodSpec{
+			Containers: []corev1.Container{
+				{
+					Name:  "nginx",
+					Image: "nginx",
+				},
+			},
+		},
 	}, metav1.CreateOptions{})
 	_, _ = kubernetesAdmin.CoreV1().Pods("ns-2").Create(ctx, &corev1.Pod{
-		ObjectMeta: metav1.ObjectMeta{Name: "a-pod-in-ns-2"},
-		Spec:       corev1.PodSpec{Containers: []corev1.Container{{Name: "nginx", Image: "nginx"}}},
+		ObjectMeta: metav1.ObjectMeta{
+			Name: "a-pod-in-ns-2",
+		},
+		Spec: corev1.PodSpec{
+			Containers: []corev1.Container{
+				{
+					Name:  "nginx",
+					Image: "nginx",
+				},
+			},
+		},
 	}, metav1.CreateOptions{})
 	_, _ = kubernetesAdmin.CoreV1().ConfigMaps("default").
 		Create(ctx, &corev1.ConfigMap{ObjectMeta: metav1.ObjectMeta{Name: "a-configmap-to-delete"}}, metav1.CreateOptions{})

pkg/mcp/pods.go

@@ -4,30 +4,33 @@ import (
 	"context"
 	"errors"
 	"fmt"
+
 	"github.com/mark3labs/mcp-go/mcp"
 	"github.com/mark3labs/mcp-go/server"
 )
 
 func (s *Server) initPods() []server.ServerTool {
 	return []server.ServerTool{
-		{mcp.NewTool("pods_list",
+		{Tool: mcp.NewTool("pods_list",
 			mcp.WithDescription("List all the Kubernetes pods in the current cluster from all namespaces"),
-		), s.podsListInAllNamespaces},
-		{mcp.NewTool("pods_list_in_namespace",
+			mcp.WithString("labelSelector", mcp.Description("Optional Kubernetes label selector (e.g. 'app=myapp,env=prod' or 'app in (myapp,yourapp)'), use this option when you want to filter the pods by label"), mcp.Pattern("([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9]")),
+		), Handler: s.podsListInAllNamespaces},
+		{Tool: mcp.NewTool("pods_list_in_namespace",
 			mcp.WithDescription("List all the Kubernetes pods in the specified namespace in the current cluster"),
 			mcp.WithString("namespace", mcp.Description("Namespace to list pods from"), mcp.Required()),
-		), s.podsListInNamespace},
-		{mcp.NewTool("pods_get",
+			mcp.WithString("labelSelector", mcp.Description("Optional Kubernetes label selector (e.g. 'app=myapp,env=prod' or 'app in (myapp,yourapp)'), use this option when you want to filter the pods by label"), mcp.Pattern("([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9]")),
+		), Handler: s.podsListInNamespace},
+		{Tool: mcp.NewTool("pods_get",
 			mcp.WithDescription("Get a Kubernetes Pod in the current or provided namespace with the provided name"),
 			mcp.WithString("namespace", mcp.Description("Namespace to get the Pod from")),
 			mcp.WithString("name", mcp.Description("Name of the Pod"), mcp.Required()),
-		), s.podsGet},
-		{mcp.NewTool("pods_delete",
+		), Handler: s.podsGet},
+		{Tool: mcp.NewTool("pods_delete",
 			mcp.WithDescription("Delete a Kubernetes Pod in the current or provided namespace with the provided name"),
 			mcp.WithString("namespace", mcp.Description("Namespace to delete the Pod from")),
 			mcp.WithString("name", mcp.Description("Name of the Pod to delete"), mcp.Required()),
-		), s.podsDelete},
-		{mcp.NewTool("pods_exec",
+		), Handler: s.podsDelete},
+		{Tool: mcp.NewTool("pods_exec",
 			mcp.WithDescription("Execute a command in a Kubernetes Pod in the current or provided namespace with the provided name and command"),
 			mcp.WithString("namespace", mcp.Description("Namespace of the Pod where the command will be executed")),
 			mcp.WithString("name", mcp.Description("Name of the Pod where the command will be executed"), mcp.Required()),
@@ -45,25 +48,31 @@ func (s *Server) initPods() []server.ServerTool {
 				mcp.Required(),
 			),
 			mcp.WithString("container", mcp.Description("Name of the Pod container where the command will be executed (Optional)")),
-		), s.podsExec},
-		{mcp.NewTool("pods_log",
+		), Handler: s.podsExec},
+		{Tool: mcp.NewTool("pods_log",
 			mcp.WithDescription("Get the logs of a Kubernetes Pod in the current or provided namespace with the provided name"),
 			mcp.WithString("namespace", mcp.Description("Namespace to get the Pod logs from")),
 			mcp.WithString("name", mcp.Description("Name of the Pod to get the logs from"), mcp.Required()),
 			mcp.WithString("container", mcp.Description("Name of the Pod container to get the logs from (Optional)")),
-		), s.podsLog},
-		{mcp.NewTool("pods_run",
+		), Handler: s.podsLog},
+		{Tool: mcp.NewTool("pods_run",
 			mcp.WithDescription("Run a Kubernetes Pod in the current or provided namespace with the provided container image and optional name"),
 			mcp.WithString("namespace", mcp.Description("Namespace to run the Pod in")),
 			mcp.WithString("name", mcp.Description("Name of the Pod (Optional, random name if not provided)")),
 			mcp.WithString("image", mcp.Description("Container Image to run in the Pod"), mcp.Required()),
 			mcp.WithNumber("port", mcp.Description("TCP/IP port to expose from the Pod container (Optional, no port exposed if not provided)")),
-		), s.podsRun},
+		), Handler: s.podsRun},
 	}
 }
 
-func (s *Server) podsListInAllNamespaces(ctx context.Context, _ mcp.CallToolRequest) (*mcp.CallToolResult, error) {
-	ret, err := s.k.PodsListInAllNamespaces(ctx)
+func (s *Server) podsListInAllNamespaces(ctx context.Context, ctr mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+	labelSelector := ctr.Params.Arguments["labelSelector"]
+	var selector string
+	if labelSelector != nil {
+		selector = labelSelector.(string)
+	}
+
+	ret, err := s.k.PodsListInAllNamespaces(ctx, selector)
 	if err != nil {
 		return NewTextResult("", fmt.Errorf("failed to list pods in all namespaces: %v", err)), nil
 	}
@@ -75,7 +84,12 @@ func (s *Server) podsListInNamespace(ctx context.Context, ctr mcp.CallToolReques
 	if ns == nil {
 		return NewTextResult("", errors.New("failed to list pods in namespace, missing argument namespace")), nil
 	}
-	ret, err := s.k.PodsListInNamespace(ctx, ns.(string))
+	labelSelector := ctr.Params.Arguments["labelSelector"]
+	var selector string
+	if labelSelector != nil {
+		selector = labelSelector.(string)
+	}
+	ret, err := s.k.PodsListInNamespace(ctx, ns.(string), selector)
 	if err != nil {
 		return NewTextResult("", fmt.Errorf("failed to list pods in namespace %s: %v", ns, err)), nil
 	}