mcp-server-kubernetes/dist/utils/streamable-http.js

MCP server for interacting with Kubernetes clusters via kubectl

import express from "express";
import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
export function startStreamableHTTPServer(server) {
    const app = express();
    app.use(express.json());
    app.post("/mcp", async (req, res) => {
        // In stateless mode, create a new instance of transport and server for each request
        // to ensure complete isolation. A single instance would cause request ID collisions
        // when multiple clients connect concurrently.
        try {
            // DNS rebinding protection is disabled by default for backwards compatibility. If you are running this server
            // locally, make sure to set DNS_REBINDING_PROTECTION=true
            const enableDnsRebindingProtection = process.env.DNS_REBINDING_PROTECTION === "true";
            const allowedHosts = process.env.DNS_REBINDING_ALLOWED_HOST
                ? [process.env.DNS_REBINDING_ALLOWED_HOST]
                : ["127.0.0.1"];
            const transport = new StreamableHTTPServerTransport({
                sessionIdGenerator: undefined,
                enableDnsRebindingProtection,
                allowedHosts,
            });
            res.on("close", () => {
                transport.close();
                server.close();
            });
            await server.connect(transport);
            await transport.handleRequest(req, res, req.body);
        }
        catch (error) {
            console.error("Error handling MCP request:", error);
            if (!res.headersSent) {
                res.status(500).json({
                    jsonrpc: "2.0",
                    error: {
                        code: -32603,
                        message: "Internal server error",
                    },
                    id: null,
                });
            }
        }
    });
    // SSE notifications not supported in stateless mode
    app.get("/mcp", async (req, res) => {
        console.log("Received GET MCP request");
        res.writeHead(405).end(JSON.stringify({
            jsonrpc: "2.0",
            error: {
                code: -32000,
                message: "Method not allowed.",
            },
            id: null,
        }));
    });
    // Session termination not needed in stateless mode
    app.delete("/mcp", async (req, res) => {
        console.log("Received DELETE MCP request");
        res.writeHead(405).end(JSON.stringify({
            jsonrpc: "2.0",
            error: {
                code: -32000,
                message: "Method not allowed.",
            },
            id: null,
        }));
    });
    let port = 3000;
    try {
        port = parseInt(process.env.PORT || "3000", 10);
    }
    catch (e) {
        console.error("Invalid PORT environment variable, using default port 3000.");
    }
    const host = process.env.HOST || "localhost";
    const httpServer = app.listen(port, host, () => {
        console.log(`mcp-kubernetes-server is listening on port ${port}\nUse the following url to connect to the server:\nhttp://${host}:${port}/mcp`);
    });
    return httpServer;
}