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https://github.com/coder/coder.git
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Ethan
181e103201
## Problem Coderd can expose an MCP server at `/api/experimental/mcp/http` (we have this enabled on dogfood). Its workspace tools dialed agents through a per-call client-side tailnet stack. Every tool call re-created a WireGuard device, netstack, magicsock + UDP sockets, DERP connection, coordinator websocket, and their goroutines — in a process that already runs a long-lived shared tailnet. The duplicate stacks drove up resource usage under load. ## Fix Route this server's tool calls through the existing shared tailnet, so none of those transports are reconstructed per call. Closing an `AgentConn` now releases a tunnel reference instead of tearing down a transport. ## Potential follow-up `coder exp mcp server` still builds a fresh tailnet per call. It pays per-call latency and causes coordinator/DERP churn. A shared CLI tailnet is more involved — unlike coderd, the CLI has no existing shared tailnet to reuse, so it would need a new long-lived client-side tailnet with reconnect, sleep/wake, and idle-destination handling. There's less motivation to optimize this, given the client-side MCP does not compete for resources with coderd. Closes CODAGT-199 > Generated by mux, but reviewed by a human
65 lines
2.0 KiB
Go
65 lines
2.0 KiB
Go
package coderd
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import (
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"fmt"
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"net/http"
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"cdr.dev/slog/v3"
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"github.com/coder/coder/v2/coderd/httpapi"
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"github.com/coder/coder/v2/coderd/httpmw"
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"github.com/coder/coder/v2/coderd/mcp"
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"github.com/coder/coder/v2/codersdk"
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"github.com/coder/coder/v2/codersdk/toolsdk"
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)
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type MCPToolset string
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const (
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MCPToolsetStandard MCPToolset = "standard"
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MCPToolsetChatGPT MCPToolset = "chatgpt"
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)
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// mcpHTTPHandler creates the MCP HTTP transport handler
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// It supports a "toolset" query parameter to select the set of tools to register.
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func (api *API) mcpHTTPHandler() http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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// Create MCP server instance for each request
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mcpServer, err := mcp.NewServer(api.Logger.Named("mcp"))
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if err != nil {
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api.Logger.Error(r.Context(), "failed to create MCP server", slog.Error(err))
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httpapi.Write(r.Context(), w, http.StatusInternalServerError, codersdk.Response{
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Message: "MCP server initialization failed",
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})
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return
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}
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// Extract the original session token from the request
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authenticatedClient := codersdk.New(api.AccessURL,
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codersdk.WithSessionToken(httpmw.APITokenFromRequest(r)))
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toolOpt := toolsdk.WithAgentConnFunc(api.agentProvider.AgentConn)
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toolset := MCPToolset(r.URL.Query().Get("toolset"))
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// Default to standard toolset if no toolset is specified.
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if toolset == "" {
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toolset = MCPToolsetStandard
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}
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switch toolset {
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case MCPToolsetStandard:
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if err := mcpServer.RegisterTools(authenticatedClient, toolOpt); err != nil {
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api.Logger.Warn(r.Context(), "failed to register MCP tools", slog.Error(err))
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}
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case MCPToolsetChatGPT:
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if err := mcpServer.RegisterChatGPTTools(authenticatedClient, toolOpt); err != nil {
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api.Logger.Warn(r.Context(), "failed to register MCP tools", slog.Error(err))
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}
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default:
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httpapi.Write(r.Context(), w, http.StatusBadRequest, codersdk.Response{
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Message: fmt.Sprintf("Invalid toolset: %s", toolset),
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})
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return
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}
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// Handle the MCP request
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mcpServer.ServeHTTP(w, r)
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})
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}
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