feat(kubernetes): resources_list can list any resource in the cluster

Author: manusa

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/spf13/viper v1.19.0
 	golang.org/x/net v0.33.0
 	k8s.io/api v0.32.1
+	k8s.io/apiextensions-apiserver v0.32.0
 	k8s.io/apimachinery v0.32.1
 	k8s.io/client-go v0.32.1
 	sigs.k8s.io/controller-runtime v0.20.1
@@ -63,7 +64,6 @@ require (
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
-	k8s.io/apiextensions-apiserver v0.32.0 // indirect
 	k8s.io/klog/v2 v2.130.1 // indirect
 	k8s.io/kube-openapi v0.0.0-20241105132330-32ad38e42d3f // indirect
 	k8s.io/utils v0.0.0-20241104100929-3ea5e8cea738 // indirect

pkg/kubernetes/resources.go

@@ -22,7 +22,6 @@ const (
 	AppKubernetesPartOf    = "app.kubernetes.io/part-of"
 )
 
-// TODO: WIP
 func (k *Kubernetes) ResourcesList(ctx context.Context, gvk *schema.GroupVersionKind, namespace string) (string, error) {
 	client, err := dynamic.NewForConfig(k.cfg)
 	if err != nil {

pkg/mcp/resources.go

@@ -6,9 +6,25 @@ import (
 	"fmt"
 	"github.com/manusa/kubernetes-mcp-server/pkg/kubernetes"
 	"github.com/mark3labs/mcp-go/mcp"
+	"k8s.io/apimachinery/pkg/runtime/schema"
 )
 
 func (s *Sever) initResources() {
+	s.server.AddTool(mcp.NewTool(
+		"resources_list",
+		mcp.WithDescription("List Kubernetes resources in the current cluster by providing their apiVersion and kind and optionally the namespace"),
+		mcp.WithString("apiVersion",
+			mcp.Description("apiVersion of the resources (examples of valid apiVersion are: v1, apps/v1, networking.k8s.io/v1)"),
+			mcp.Required(),
+		),
+		mcp.WithString("kind",
+			mcp.Description("kind of the resources (examples of valid kind are: Pod, Service, Deployment, Ingress)"),
+			mcp.Required(),
+		),
+		mcp.WithString("namespace",
+			mcp.Description("Optional Namespace to retrieve the namespaced resources from (ignored in case of cluster scoped resources). If not provided, will list resources from all namespaces"),
+		),
+	), resourcesList)
 	s.server.AddTool(mcp.NewTool(
 		"resources_create_or_update",
 		mcp.WithDescription("Create or update a Kubernetes resource in the current cluster by providing a YAML or JSON representation of the resource"),
@@ -19,6 +35,34 @@ func (s *Sever) initResources() {
 	), resourcesCreateOrUpdate)
 }
 
+func resourcesList(ctx context.Context, ctr mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+	k, err := kubernetes.NewKubernetes()
+	if err != nil {
+		return NewTextResult("", fmt.Errorf("failed to create or update resources: %v", err)), nil
+	}
+	apiVersion := ctr.Params.Arguments["apiVersion"]
+	if apiVersion == nil {
+		return NewTextResult("", errors.New("failed to list resources, missing argument apiVersion")), nil
+	}
+	kind := ctr.Params.Arguments["kind"]
+	if kind == nil {
+		return NewTextResult("", errors.New("failed to list resources, missing argument kind")), nil
+	}
+	namespace := ctr.Params.Arguments["namespace"]
+	if namespace == nil {
+		namespace = ""
+	}
+	gv, err := schema.ParseGroupVersion(apiVersion.(string))
+	if err != nil {
+		return NewTextResult("", errors.New("failed to list resources, invalid argument apiVersion")), nil
+	}
+	ret, err := k.ResourcesList(ctx, &schema.GroupVersionKind{Group: gv.Group, Version: gv.Version, Kind: kind.(string)}, namespace.(string))
+	if err != nil {
+		return NewTextResult("", fmt.Errorf("failed to list resources: %v", err)), nil
+	}
+	return NewTextResult(ret, err), nil
+}
+
 func resourcesCreateOrUpdate(ctx context.Context, ctr mcp.CallToolRequest) (*mcp.CallToolResult, error) {
 	k, err := kubernetes.NewKubernetes()
 	if err != nil {

pkg/mcp/resources_test.go

@@ -3,11 +3,88 @@ package mcp
 import (
 	v1 "k8s.io/apiextensions-apiserver/pkg/client/clientset/clientset/typed/apiextensions/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/client-go/dynamic"
+	"sigs.k8s.io/yaml"
 	"testing"
 )
 
+func TestResourcesList(t *testing.T) {
+	testCase(t, func(c *mcpContext) {
+		c.withEnvTest()
+		t.Run("resources_list with missing apiVersion returns error", func(t *testing.T) {
+			toolResult, _ := c.callTool("resources_list", map[string]interface{}{})
+			if !toolResult.IsError {
+				t.Fatalf("call tool should fail")
+				return
+			}
+			if toolResult.Content[0].(map[string]interface{})["text"].(string) != "failed to list resources, missing argument apiVersion" {
+				t.Fatalf("invalid error message, got %v", toolResult.Content[0].(map[string]interface{})["text"].(string))
+				return
+			}
+		})
+		t.Run("resources_list with missing kind returns error", func(t *testing.T) {
+			toolResult, _ := c.callTool("resources_list", map[string]interface{}{"apiVersion": "v1"})
+			if !toolResult.IsError {
+				t.Fatalf("call tool should fail")
+				return
+			}
+			if toolResult.Content[0].(map[string]interface{})["text"].(string) != "failed to list resources, missing argument kind" {
+				t.Fatalf("invalid error message, got %v", toolResult.Content[0].(map[string]interface{})["text"].(string))
+				return
+			}
+		})
+		t.Run("resources_list with invalid apiVersion returns error", func(t *testing.T) {
+			toolResult, _ := c.callTool("resources_list", map[string]interface{}{"apiVersion": "invalid/api/version", "kind": "Pod"})
+			if !toolResult.IsError {
+				t.Fatalf("call tool should fail")
+				return
+			}
+			if toolResult.Content[0].(map[string]interface{})["text"].(string) != "failed to list resources, invalid argument apiVersion" {
+				t.Fatalf("invalid error message, got %v", toolResult.Content[0].(map[string]interface{})["text"].(string))
+				return
+			}
+		})
+		t.Run("resources_list with nonexistent apiVersion returns error", func(t *testing.T) {
+			toolResult, _ := c.callTool("resources_list", map[string]interface{}{"apiVersion": "custom.non.existent.example.com/v1", "kind": "Custom"})
+			if !toolResult.IsError {
+				t.Fatalf("call tool should fail")
+				return
+			}
+			if toolResult.Content[0].(map[string]interface{})["text"].(string) != `failed to list resources: no matches for kind "Custom" in version "custom.non.existent.example.com/v1"` {
+				t.Fatalf("invalid error message, got %v", toolResult.Content[0].(map[string]interface{})["text"].(string))
+				return
+			}
+		})
+		namespaces, err := c.callTool("resources_list", map[string]interface{}{"apiVersion": "v1", "kind": "Namespace"})
+		t.Run("resources_list returns namespaces", func(t *testing.T) {
+			if err != nil {
+				t.Fatalf("call tool failed %v", err)
+				return
+			}
+			if namespaces.IsError {
+				t.Fatalf("call tool failed")
+				return
+			}
+		})
+		var decodedNamespaces []unstructured.Unstructured
+		err = yaml.Unmarshal([]byte(namespaces.Content[0].(map[string]interface{})["text"].(string)), &decodedNamespaces)
+		t.Run("resources_list has yaml content", func(t *testing.T) {
+			if err != nil {
+				t.Fatalf("invalid tool result content %v", err)
+				return
+			}
+		})
+		t.Run("resources_list returns more than 2 items", func(t *testing.T) {
+			if len(decodedNamespaces) < 3 {
+				t.Fatalf("invalid namespace count, expected >2, got %v", len(decodedNamespaces))
+				return
+			}
+		})
+	})
+}
+
 func TestResourcesCreateOrUpdate(t *testing.T) {
 	testCase(t, func(c *mcpContext) {
 		c.withEnvTest()