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ThomasK33ThomasK33
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feat(mcp): implement MCP HTTP server with toolsdk integration
- Add MCP HTTP server with streamable transport support - Integrate with existing toolsdk for Coder workspace operations - Add comprehensive E2E tests with OAuth2 bearer token support - Register MCP endpoint at /api/experimental/mcp/http with authentication - Support RFC 6750 Bearer token authentication for MCP clients Change-Id: Ib9024569ae452729908797c42155006aa04330af Signed-off-by: Thomas Kosiewski <tk@coder.com>
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‎coderd/coderd.go

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@@ -972,6 +972,10 @@ func New(options *Options) *API {
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r.Route("/aitasks", func(r chi.Router) {
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r.Get("/prompts", api.aiTasksPrompts)
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})
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r.Route("/mcp", func(r chi.Router) {
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// MCP HTTP transport endpoint with mandatory authentication
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r.Mount("/http", api.mcpHTTPHandler())
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})
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})
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r.Route("/api/v2", func(r chi.Router) {

‎coderd/httpmw/apikey.go

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@@ -653,8 +653,8 @@ func APITokenFromRequest(r *http.Request) string {
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// RFC 6750 Bearer Token support (added as fallback methods)
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// Check Authorization: Bearer <token> header
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authHeader := r.Header.Get("Authorization")
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if strings.HasPrefix(authHeader, "Bearer ") {
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return strings.TrimPrefix(authHeader, "Bearer ")
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if after, ok := strings.CutPrefix(authHeader, "Bearer "); ok {
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return after
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}
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// Check access_token query parameter

‎coderd/mcp/mcp.go

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@@ -0,0 +1,137 @@
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package mcp
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import (
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"bytes"
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"context"
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"encoding/json"
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"fmt"
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"net/http"
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"time"
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"cdr.dev/slog"
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"github.com/mark3labs/mcp-go/mcp"
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"github.com/mark3labs/mcp-go/server"
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"golang.org/x/xerrors"
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"github.com/coder/coder/v2/buildinfo"
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"github.com/coder/coder/v2/coderd/database"
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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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const (
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// MCPServerName is the name used for the MCP server.
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MCPServerName = "Coder"
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// MCPServerInstructions is the instructions text for the MCP server.
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MCPServerInstructions = "Coder MCP Server providing workspace and template management tools"
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)
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// Server represents an MCP HTTP server instance
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type Server struct {
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Logger slog.Logger
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// mcpServer is the underlying MCP server
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mcpServer *server.MCPServer
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// streamableServer handles HTTP transport
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streamableServer *server.StreamableHTTPServer
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}
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// NewServer creates a new MCP HTTP server
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func NewServer(db database.Store, logger slog.Logger) (*Server, error) {
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// Create the core MCP server
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mcpSrv := server.NewMCPServer(
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MCPServerName,
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buildinfo.Version(),
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server.WithInstructions(MCPServerInstructions),
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)
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// Create logger adapter for mcp-go
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mcpLogger := &mcpLoggerAdapter{logger: logger}
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// Create streamable HTTP server with configuration
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streamableServer := server.NewStreamableHTTPServer(mcpSrv,
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server.WithHeartbeatInterval(30*time.Second),
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server.WithLogger(mcpLogger),
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)
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return &Server{
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Logger: logger,
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mcpServer: mcpSrv,
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streamableServer: streamableServer,
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}, nil
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}
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// ServeHTTP implements http.Handler interface
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func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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s.streamableServer.ServeHTTP(w, r)
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}
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// RegisterTools registers all available MCP tools with the server
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func (s *Server) RegisterTools(client *codersdk.Client) error {
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// Create tool dependencies
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toolDeps, err := toolsdk.NewDeps(client)
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if err != nil {
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return xerrors.Errorf("failed to initialize tool dependencies: %w", err)
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}
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// Register all available tools
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for _, tool := range toolsdk.All {
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// Skip user-dependent tools if no authenticated client
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if !tool.UserClientOptional && client == nil {
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s.Logger.Warn(context.Background(), "Tool requires authentication and will not be available", slog.F("tool", tool.Name))
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continue
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}
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s.mcpServer.AddTools(mcpFromSDK(tool, toolDeps))
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}
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return nil
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}
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// mcpFromSDK adapts a toolsdk.Tool to go-mcp's server.ServerTool
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func mcpFromSDK(sdkTool toolsdk.GenericTool, tb toolsdk.Deps) server.ServerTool {
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if sdkTool.Schema.Properties == nil {
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panic("developer error: schema properties cannot be nil")
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}
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return server.ServerTool{
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Tool: mcp.Tool{
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Name: sdkTool.Name,
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Description: sdkTool.Description,
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InputSchema: mcp.ToolInputSchema{
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Type: "object",
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Properties: sdkTool.Schema.Properties,
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Required: sdkTool.Schema.Required,
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},
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},
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Handler: func(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
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var buf bytes.Buffer
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if err := json.NewEncoder(&buf).Encode(request.Params.Arguments); err != nil {
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return nil, xerrors.Errorf("failed to encode request arguments: %w", err)
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}
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result, err := sdkTool.Handler(ctx, tb, buf.Bytes())
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if err != nil {
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return nil, err
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}
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return &mcp.CallToolResult{
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Content: []mcp.Content{
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mcp.NewTextContent(string(result)),
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},
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}, nil
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},
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}
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}
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// mcpLoggerAdapter adapts slog.Logger to the mcp-go util.Logger interface
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type mcpLoggerAdapter struct {
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logger slog.Logger
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}
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func (l *mcpLoggerAdapter) Infof(format string, v ...any) {
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l.logger.Info(context.Background(), fmt.Sprintf(format, v...))
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}
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func (l *mcpLoggerAdapter) Errorf(format string, v ...any) {
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l.logger.Error(context.Background(), fmt.Sprintf(format, v...))
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}

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