mcp: adds remote template support (knative#2951)

Signed-off-by: kapil <[email protected]>

Author: KapilSareen

pkg/mcp/help.go

@@ -2,13 +2,75 @@ package mcp
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
+	"io"
+	"net/http"
 	"os/exec"
 	"strings"
 
 	"github.com/mark3labs/mcp-go/mcp"
 )
 
+type template struct {
+	Repository   string `json:"repository"`
+	Language     string `json:"language"`
+	TemplateName string `json:"template"`
+}
+
+func fetchTemplates() ([]template, error) {
+	var out []template
+	seen := make(map[string]bool)
+
+	for _, repoURL := range TEMPLATE_RESOURCE_URIS {
+		owner, repo := parseGitHubURL(repoURL)
+		api := fmt.Sprintf("https://api.github.com/repos/%s/%s/git/trees/main?recursive=1", owner, repo)
+
+		resp, err := http.Get(api)
+		if err != nil {
+			return nil, err
+		}
+		defer resp.Body.Close()
+
+		body, err := io.ReadAll(resp.Body)
+		if err != nil {
+			return nil, err
+		}
+
+		var tree struct {
+			Tree []struct {
+				Path string `json:"path"`
+			} `json:"tree"`
+		}
+		if err := json.Unmarshal(body, &tree); err != nil {
+			return nil, err
+		}
+
+		for _, item := range tree.Tree {
+			parts := strings.Split(item.Path, "/")
+			if len(parts) >= 2 && !strings.HasPrefix(parts[0], ".") {
+				lang, name := parts[0], parts[1]
+				key := lang + "/" + name
+				if !seen[key] {
+					out = append(out, template{
+						Language:     lang,
+						TemplateName: name,
+						Repository:   repoURL,
+					})
+					seen[key] = true
+				}
+			}
+		}
+	}
+	return out, nil
+}
+
+func parseGitHubURL(url string) (owner, repo string) {
+	trim := strings.TrimPrefix(url, "https://github.com/")
+	parts := strings.Split(trim, "/")
+	return parts[0], parts[1]
+}
+
 func handleRootHelpResource(ctx context.Context, request mcp.ReadResourceRequest) ([]mcp.ResourceContents, error) {
 	content, err := exec.Command("func", "--help").Output()
 	if err != nil {
@@ -39,6 +101,25 @@ func runHelpCommand(args []string, uri string) ([]mcp.ResourceContents, error) {
 	}, nil
 }
 
+func handleListTemplatesResource(ctx context.Context, request mcp.ReadResourceRequest) ([]mcp.ResourceContents, error) {
+	templates, err := fetchTemplates()
+	if err != nil {
+		return nil, err
+	}
+	content, err := json.MarshalIndent(templates, "", "  ")
+	if err != nil {
+		return nil, err
+	}
+
+	return []mcp.ResourceContents{
+		mcp.TextResourceContents{
+			URI:      "func://templates",
+			MIMEType: "text/plain",
+			Text:     string(content),
+		},
+	}, nil
+}
+
 func handleCmdHelpPrompt(ctx context.Context, request mcp.GetPromptRequest) (*mcp.GetPromptResult, error) {
 	cmd := request.Params.Arguments["cmd"]
 	if cmd == "" {
@@ -86,3 +167,22 @@ func handleRootHelpPrompt(ctx context.Context, request mcp.GetPromptRequest) (*m
 		},
 	), nil
 }
+
+func handleListTemplatesPrompt(ctx context.Context, request mcp.GetPromptRequest) (*mcp.GetPromptResult, error) {
+	return mcp.NewGetPromptResult(
+		"List Templates Prompt",
+		[]mcp.PromptMessage{
+			mcp.NewPromptMessage(
+				mcp.RoleUser,
+				mcp.NewTextContent("List available function templates"),
+			),
+			mcp.NewPromptMessage(
+				mcp.RoleAssistant,
+				mcp.NewEmbeddedResource(mcp.TextResourceContents{
+					URI:      "func://templates",
+					MIMEType: "text/plain",
+				}),
+			),
+		},
+	), nil
+}

pkg/mcp/mcp.go

@@ -7,6 +7,10 @@ import (
 	"github.com/mark3labs/mcp-go/server"
 )
 
+var TEMPLATE_RESOURCE_URIS = []string{
+	"https://github.com/gauron99/func-templates",
+}
+
 type MCPServer struct {
 	server *server.MCPServer
 }
@@ -43,7 +47,7 @@ func NewServer() *MCPServer {
 
 			// Optional flags
 			mcp.WithString("template", mcp.Description("Function template (e.g., http, cloudevents)")),
-			mcp.WithString("repository", mcp.Description("URI to Git repo containing the template")),
+			mcp.WithString("repository", mcp.Description("URI to Git repo containing the template. Overrides default template selection when provided.")),
 			mcp.WithBoolean("confirm", mcp.Description("Prompt to confirm options interactively")),
 			mcp.WithBoolean("verbose", mcp.Description("Print verbose logs")),
 		),
@@ -325,6 +329,14 @@ func NewServer() *MCPServer {
 		return runHelpCommand([]string{"config", "envs", "remove"}, "func://config/envs/remove/docs")
 	})
 
+	// Static resource for listing available templates
+	mcpServer.AddResource(mcp.NewResource(
+		"func://templates",
+		"Available Templates",
+		mcp.WithResourceDescription("List of available function templates"),
+		mcp.WithMIMEType("plain/text"),
+	), handleListTemplatesResource)
+
 	mcpServer.AddPrompt(mcp.NewPrompt("help",
 		mcp.WithPromptDescription("help prompt for the root command"),
 	), handleRootHelpPrompt)
@@ -337,6 +349,10 @@ func NewServer() *MCPServer {
 		),
 	), handleCmdHelpPrompt)
 
+	mcpServer.AddPrompt(mcp.NewPrompt("list_templates",
+		mcp.WithPromptDescription("prompt to list available function templates"),
+	), handleListTemplatesPrompt)
+
 	return &MCPServer{
 		server: mcpServer,
 	}