func/pkg/mcp/mcp.go

package mcp

import (
	"context"
	"fmt"
	"os/exec"

	"github.com/mark3labs/mcp-go/mcp"
	"github.com/mark3labs/mcp-go/server"
)

type MCPServer struct {
	server *server.MCPServer
}

func NewServer() *MCPServer {
	mcpServer := server.NewMCPServer(
		"func-mcp",
		"1.0.0",
		server.WithToolCapabilities(true),
	)

	mcpServer.AddTool(
		mcp.NewTool("healthcheck",
			mcp.WithDescription("Checks if the server is running"),
		),
		handleHealthCheckTool,
	)

	mcpServer.AddTool(
		mcp.NewTool("create",
			mcp.WithDescription("Creates a knative function in the current directory"),
			mcp.WithString("name",
				mcp.Required(),
				mcp.Description("Name of the function to be created"),
			),
			mcp.WithString("language",
				mcp.Required(),
				mcp.Description("Language/Runtime of the function to be created"),
			),
			mcp.WithString("cwd",
				mcp.Required(),
				mcp.Description("Current working directory of the MCP client"),
			),
		),
		handleCreateTool,
	)

	mcpServer.AddTool(
		mcp.NewTool("deploy",
			mcp.WithDescription("Deploys the function to the cluster"),
			mcp.WithString("registry",
				mcp.Required(),
				mcp.Description("Name of the registry to be used to push the function image"),
			),
			mcp.WithString("cwd",
				mcp.Required(),
				mcp.Description("Full path of the function to be deployed"),
			),
			mcp.WithString("builder",
				mcp.Required(),
				mcp.Description("Builder to be used to build the function image"),
			),
		),
		handleDeployTool,
	)

	mcpServer.AddTool(
		mcp.NewTool("list",
			mcp.WithDescription("Lists all the functions deployed in the cluster"),
		),
		handleListTool,
	)

	return &MCPServer{
		server: mcpServer,
	}
}

func (s *MCPServer) Start() error {
	return server.ServeStdio(s.server)
}

func handleHealthCheckTool(
	ctx context.Context,
	request mcp.CallToolRequest,
) (*mcp.CallToolResult, error) {
	body := []byte(fmt.Sprintf(`{"message": "%s"}`, "The MCP server is running!"))
	return mcp.NewToolResultText(string(body)), nil
}

func handleCreateTool(
	ctx context.Context,
	request mcp.CallToolRequest,
) (*mcp.CallToolResult, error) {
	cwd, err := request.RequireString("cwd")
	if err != nil {
		return mcp.NewToolResultError(err.Error()), nil
	}
	name, err := request.RequireString("name")
	if err != nil {
		return mcp.NewToolResultError(err.Error()), nil
	}
	language, err := request.RequireString("language")
	if err != nil {
		return mcp.NewToolResultError(err.Error()), nil
	}

	cmd := exec.Command("func", "create", "-l", language, name)
	cmd.Dir = cwd
	out, err := cmd.Output()
	if err != nil {
		return mcp.NewToolResultError(err.Error()), nil
	}
	body := []byte(fmt.Sprintf(`{"result": "%s"}`, out))
	return mcp.NewToolResultText(string(body)), nil
}

func handleDeployTool(
	ctx context.Context,
	request mcp.CallToolRequest,
) (*mcp.CallToolResult, error) {
	cwd, err := request.RequireString("cwd")
	if err != nil {
		return mcp.NewToolResultError(err.Error()), nil
	}
	registry, err := request.RequireString("registry")
	if err != nil {
		return mcp.NewToolResultError(err.Error()), nil
	}
	builder, err := request.RequireString("builder")
	if err != nil {
		return mcp.NewToolResultError(err.Error()), nil
	}
	cmd := exec.Command("func", "deploy", "--registry", registry, "--builder", builder)
	cmd.Dir = cwd
	out, err := cmd.Output()
	if err != nil {
		return mcp.NewToolResultError(err.Error()), nil
	}
	body := []byte(fmt.Sprintf(`{"result": "%s"}`, out))
	return mcp.NewToolResultText(string(body)), nil
}

func handleListTool(
	ctx context.Context,
	request mcp.CallToolRequest,
) (*mcp.CallToolResult, error) {
	cmd := exec.Command("func", "list")
	out, err := cmd.Output()
	if err != nil {
		return mcp.NewToolResultError(err.Error()), nil
	}
	body := []byte(fmt.Sprintf(`{"result": "%s"}`, out))
	return mcp.NewToolResultText(string(body)), nil
}