feat:(helm) added a new tool for getting the values.yaml of the chart

Signed-off-by: Praneeth Shetty <[email protected]>

Author: PraneethShetty626

pkg/helm/helm.go

@@ -2,16 +2,18 @@ package helm
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
+	"log"
+	"time"
+
 	"helm.sh/helm/v3/pkg/action"
 	"helm.sh/helm/v3/pkg/chart/loader"
 	"helm.sh/helm/v3/pkg/cli"
 	"helm.sh/helm/v3/pkg/registry"
 	"helm.sh/helm/v3/pkg/release"
 	"k8s.io/cli-runtime/pkg/genericclioptions"
-	"log"
 	"sigs.k8s.io/yaml"
-	"time"
 )
 
 type Kubernetes interface {
@@ -140,3 +142,42 @@ func simplify(release ...*release.Release) []map[string]interface{} {
 	}
 	return ret
 }
+
+func (h *Helm) GetChartValues(ctx context.Context, chart string, version string) (string, error) {
+	// Create a show action to get chart values
+	cfg, err := h.newAction("", false)
+	if err != nil {
+		return "", err
+	}
+
+	// Create a show action to get chart values with configuration
+	show := action.NewShowWithConfig(action.ShowValues, cfg)
+	show.Version = version
+
+	// Locate the chart
+	chartRequested, err := show.LocateChart(chart, cli.New())
+	if err != nil {
+		return "", err
+	}
+
+	// Load the chart
+	chartLoaded, err := loader.Load(chartRequested)
+	if err != nil {
+		return "", err
+	}
+
+	// Get the values from the chart
+	values := chartLoaded.Values
+	if values == nil {
+		return "No values found for chart", nil
+	}
+
+	// Convert values to YAML
+	ret, err := json.MarshalIndent(values, "", "  ")
+
+	if err != nil {
+		return "", err
+	}
+
+	return string(ret), nil
+}

pkg/mcp/helm.go

@@ -44,6 +44,17 @@ func (s *Server) initHelm() []server.ServerTool {
 			mcp.WithIdempotentHintAnnotation(true),
 			mcp.WithOpenWorldHintAnnotation(true),
 		), Handler: s.helmUninstall},
+		{Tool: mcp.NewTool("helm_values",
+			mcp.WithDescription("Retrieves the default or overridden values.yaml for a specified Helm chart version. Accepts a chart reference (e.g., stable/grafana, oci://ghcr.io/nginxinc/charts/nginx-ingress) and an optional chart version. If no version is provided, the latest available version is used."),
+			mcp.WithString("chart", mcp.Description("Chart reference to extract values from, such as stable/grafana or oci://ghcr.io/nginxinc/charts/nginx-ingress"), mcp.Required()),
+			mcp.WithString("version", mcp.Description("Version of the Helm chart to retrieve values for. Optional; defaults to the latest version if not provided.")),
+			// Tool annotations
+			mcp.WithTitleAnnotation("Helm: Values"),
+			mcp.WithReadOnlyHintAnnotation(false),
+			mcp.WithDestructiveHintAnnotation(false),
+			mcp.WithIdempotentHintAnnotation(false), // TODO: consider replacing implementation with equivalent to: helm upgrade --install
+			mcp.WithOpenWorldHintAnnotation(true),
+		), Handler: s.helmChartValues},
 	}
 }
 
@@ -116,3 +127,31 @@ func (s *Server) helmUninstall(ctx context.Context, ctr mcp.CallToolRequest) (*m
 	}
 	return NewTextResult(ret, err), nil
 }
+
+func (s *Server) helmChartValues(ctx context.Context, ctr mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+	var chart string
+	ok := false
+	if chart, ok = ctr.GetArguments()["chart"].(string); !ok {
+		return NewTextResult("", fmt.Errorf("missing required argument: chart")), nil
+	}
+
+	version := ""
+	if v, ok := ctr.GetArguments()["version"].(string); ok {
+		version = v
+	}
+
+	derived, err := s.k.Derived(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to initialize derived context: %w", err)
+	}
+
+	ret, err := derived.NewHelm().GetChartValues(ctx, chart, version)
+	if err != nil {
+		if version != "" {
+			return NewTextResult("", fmt.Errorf("failed to retrieve values for Helm chart '%s' (version %s): %w", chart, version, err)), nil
+		}
+		return NewTextResult("", fmt.Errorf("failed to retrieve values for Helm chart '%s': %w", chart, err)), nil
+	}
+
+	return NewTextResult(ret, nil), nil
+}

pkg/mcp/helm_test.go

@@ -3,17 +3,18 @@ package mcp
 import (
 	"context"
 	"encoding/base64"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+
 	"github.com/containers/kubernetes-mcp-server/pkg/config"
 	"github.com/mark3labs/mcp-go/mcp"
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
-	"path/filepath"
-	"runtime"
 	"sigs.k8s.io/yaml"
-	"strings"
-	"testing"
 )
 
 func TestHelmInstall(t *testing.T) {
@@ -254,6 +255,132 @@ func TestHelmUninstallDenied(t *testing.T) {
 	})
 }
 
+func TestHelmValues(t *testing.T) {
+	testCase(t, func(c *mcpContext) {
+		c.withEnvTest()
+		_, file, _, _ := runtime.Caller(0)
+		chartPath := filepath.Join(filepath.Dir(file), "testdata", "helm-chart-with-values")
+
+		t.Run("helm_values with local chart returns values", func(t *testing.T) {
+			toolResult, err := c.callTool("helm_values", map[string]interface{}{
+				"chart": chartPath,
+			})
+			if err != nil {
+				t.Fatalf("call tool failed %v", err)
+			}
+			if toolResult.IsError {
+				t.Fatalf("call tool failed: %v", toolResult.Content[0].(mcp.TextContent).Text)
+			}
+
+			// Parse the returned YAML
+			var values map[string]interface{}
+			err = yaml.Unmarshal([]byte(toolResult.Content[0].(mcp.TextContent).Text), &values)
+			if err != nil {
+				t.Fatalf("invalid tool result content %v", err)
+			}
+
+			// Verify some expected values
+			if values["replicaCount"] != float64(1) {
+				t.Fatalf("expected replicaCount to be 1, got %v", values["replicaCount"])
+			}
+
+			if imageMap, ok := values["image"].(map[string]interface{}); ok {
+				if imageMap["repository"] != "nginx" {
+					t.Fatalf("expected image.repository to be nginx, got %v", imageMap["repository"])
+				}
+				if imageMap["tag"] != "latest" {
+					t.Fatalf("expected image.tag to be latest, got %v", imageMap["tag"])
+				}
+			} else {
+				t.Fatalf("expected image to be a map, got %T", values["image"])
+			}
+
+			if customConfig, ok := values["customConfig"].(map[string]interface{}); ok {
+				if customConfig["debug"] != false {
+					t.Fatalf("expected customConfig.debug to be false, got %v", customConfig["debug"])
+				}
+				if customConfig["logLevel"] != "info" {
+					t.Fatalf("expected customConfig.logLevel to be info, got %v", customConfig["logLevel"])
+				}
+			} else {
+				t.Fatalf("expected customConfig to be a map, got %T", values["customConfig"])
+			}
+		})
+
+		t.Run("helm_values with version parameter", func(t *testing.T) {
+			toolResult, err := c.callTool("helm_values", map[string]interface{}{
+				"chart":   chartPath,
+				"version": "1.0.0",
+			})
+			if err != nil {
+				t.Fatalf("call tool failed %v", err)
+			}
+			if toolResult.IsError {
+				t.Fatalf("call tool failed: %v", toolResult.Content[0].(mcp.TextContent).Text)
+			}
+
+			// Should still return values even with version specified
+			var values map[string]interface{}
+			err = yaml.Unmarshal([]byte(toolResult.Content[0].(mcp.TextContent).Text), &values)
+			if err != nil {
+				t.Fatalf("invalid tool result content %v", err)
+			}
+
+			if values["replicaCount"] != float64(1) {
+				t.Fatalf("expected replicaCount to be 1, got %v", values["replicaCount"])
+			}
+		})
+
+		t.Run("helm_values with chart without values returns no values message", func(t *testing.T) {
+			chartPathNoValues := filepath.Join(filepath.Dir(file), "testdata", "helm-chart-no-op")
+			toolResult, err := c.callTool("helm_values", map[string]interface{}{
+				"chart": chartPathNoValues,
+			})
+			if err != nil {
+				t.Fatalf("call tool failed %v", err)
+			}
+			if toolResult.IsError {
+				t.Fatalf("call tool failed: %v", toolResult.Content[0].(mcp.TextContent).Text)
+			}
+
+			if toolResult.Content[0].(mcp.TextContent).Text != "No values found for chart" {
+				t.Fatalf("expected 'No values found for chart', got %v", toolResult.Content[0].(mcp.TextContent).Text)
+			}
+		})
+
+		t.Run("helm_values with missing chart argument returns error", func(t *testing.T) {
+			toolResult, err := c.callTool("helm_values", map[string]interface{}{})
+			if err != nil {
+				t.Fatalf("call tool failed %v", err)
+			}
+			if !toolResult.IsError {
+				t.Fatalf("expected tool to fail with missing chart argument")
+			}
+
+			expectedError := "missing required argument: chart"
+			if !strings.Contains(toolResult.Content[0].(mcp.TextContent).Text, expectedError) {
+				t.Fatalf("expected error to contain '%s', got %v", expectedError, toolResult.Content[0].(mcp.TextContent).Text)
+			}
+		})
+
+		t.Run("helm_values with invalid chart path returns error", func(t *testing.T) {
+			toolResult, err := c.callTool("helm_values", map[string]interface{}{
+				"chart": "/non/existent/path",
+			})
+			if err != nil {
+				t.Fatalf("call tool failed %v", err)
+			}
+			if !toolResult.IsError {
+				t.Fatalf("expected tool to fail with invalid chart path")
+			}
+
+			if !strings.Contains(toolResult.Content[0].(mcp.TextContent).Text, "failed to retrieve values for Helm chart") {
+				t.Fatalf("expected error to contain failure message, got %v", toolResult.Content[0].(mcp.TextContent).Text)
+			}
+		})
+	})
+}
+
 func clearHelmReleases(ctx context.Context, kc *kubernetes.Clientset) {
 	secrets, _ := kc.CoreV1().Secrets("default").List(ctx, metav1.ListOptions{})
 	for _, secret := range secrets.Items {

pkg/mcp/testdata/helm-chart-with-values/Chart.yaml

@@ -0,0 +1,5 @@
+apiVersion: v2
+name: test-chart-with-values
+version: 1.0.0
+type: application
+description: Test chart with values for testing helm_values tool

pkg/mcp/testdata/helm-chart-with-values/values.yaml

@@ -0,0 +1,54 @@
+# Default values for test-chart-with-values.
+# This is a YAML-formatted file.
+# Declare variables to be passed into your templates.
+
+replicaCount: 1
+
+image:
+  repository: nginx
+  pullPolicy: IfNotPresent
+  tag: "latest"
+
+nameOverride: ""
+fullnameOverride: ""
+
+service:
+  type: ClusterIP
+  port: 80
+
+ingress:
+  enabled: false
+  className: ""
+  annotations: {}
+  hosts:
+    - host: chart-example.local
+      paths:
+        - path: /
+          pathType: Prefix
+  tls: []
+
+resources:
+  limits:
+    cpu: 100m
+    memory: 128Mi
+  requests:
+    cpu: 100m
+    memory: 128Mi
+
+nodeSelector: {}
+
+tolerations: []
+
+affinity: {}
+
+# Custom configuration values
+customConfig:
+  debug: false
+  logLevel: "info"
+  features:
+    - authentication
+    - authorization
+  database:
+    host: "localhost"
+    port: 5432
+    name: "myapp"