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feat(mcp): add support for running MCP server without user authentication
Change-Id: Iab480d38764eddee294a4e8cd35a9dc52add6010 Signed-off-by: Thomas Kosiewski <[email protected]>
1 parent 9fe5b71 commit 6cc32e3

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5 files changed

+253
-23
lines changed

5 files changed

+253
-23
lines changed

‎cli/exp_mcp.go

Lines changed: 74 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -5,6 +5,7 @@ import (
55
"context"
66
"encoding/json"
77
"errors"
8+
"net/url"
89
"os"
910
"path/filepath"
1011
"slices"
@@ -361,7 +362,7 @@ func (r *RootCmd) mcpServer() *serpent.Command {
361362
},
362363
Short: "Start the Coder MCP server.",
363364
Middleware: serpent.Chain(
364-
r.InitClient(client),
365+
r.TryInitClient(client),
365366
),
366367
Options: []serpent.Option{
367368
{
@@ -396,19 +397,38 @@ func mcpServerHandler(inv *serpent.Invocation, client *codersdk.Client, instruct
396397

397398
fs := afero.NewOsFs()
398399

399-
me, err := client.User(ctx, codersdk.Me)
400-
if err != nil {
401-
cliui.Errorf(inv.Stderr, "Failed to log in to the Coder deployment.")
402-
cliui.Errorf(inv.Stderr, "Please check your URL and credentials.")
403-
cliui.Errorf(inv.Stderr, "Tip: Run `coder whoami` to check your credentials.")
404-
return err
405-
}
406400
cliui.Infof(inv.Stderr, "Starting MCP server")
407-
cliui.Infof(inv.Stderr, "User : %s", me.Username)
408-
cliui.Infof(inv.Stderr, "URL : %s", client.URL)
409-
cliui.Infof(inv.Stderr, "Instructions : %q", instructions)
401+
402+
// Check authentication status
403+
var username string
404+
405+
// Check authentication status first
406+
if client != nil && client.URL != nil && client.SessionToken() != "" {
407+
// Try to validate the client
408+
me, err := client.User(ctx, codersdk.Me)
409+
if err == nil {
410+
username = me.Username
411+
cliui.Infof(inv.Stderr, "Authentication : Successful")
412+
cliui.Infof(inv.Stderr, "User : %s", username)
413+
} else {
414+
// Authentication failed but we have a client URL
415+
cliui.Warnf(inv.Stderr, "Authentication : Failed (%s)", err)
416+
cliui.Warnf(inv.Stderr, "Some tools that require authentication will not be available.")
417+
}
418+
} else {
419+
cliui.Infof(inv.Stderr, "Authentication : None")
420+
}
421+
422+
// Display URL separately from authentication status
423+
if client != nil && client.URL != nil {
424+
cliui.Infof(inv.Stderr, "URL : %s", client.URL.String())
425+
} else {
426+
cliui.Infof(inv.Stderr, "URL : Not configured")
427+
}
428+
429+
cliui.Infof(inv.Stderr, "Instructions : %q", instructions)
410430
if len(allowedTools) > 0 {
411-
cliui.Infof(inv.Stderr, "Allowed Tools : %v", allowedTools)
431+
cliui.Infof(inv.Stderr, "Allowed Tools : %v", allowedTools)
412432
}
413433
cliui.Infof(inv.Stderr, "Press Ctrl+C to stop the server")
414434

@@ -431,13 +451,33 @@ func mcpServerHandler(inv *serpent.Invocation, client *codersdk.Client, instruct
431451
// Get the workspace agent token from the environment.
432452
toolOpts := make([]func(*toolsdk.Deps), 0)
433453
var hasAgentClient bool
434-
if agentToken, err := getAgentToken(fs); err == nil && agentToken != "" {
435-
hasAgentClient = true
436-
agentClient := agentsdk.New(client.URL)
437-
agentClient.SetSessionToken(agentToken)
438-
toolOpts = append(toolOpts, toolsdk.WithAgentClient(agentClient))
454+
455+
var agentURL *url.URL
456+
if client != nil && client.URL != nil {
457+
agentURL = client.URL
458+
} else if agntURL, err := getAgentURL(); err == nil {
459+
agentURL = agntURL
460+
}
461+
462+
// First check if we have a valid client URL, which is required for agent client
463+
if agentURL == nil {
464+
cliui.Infof(inv.Stderr, "Agent URL : Not configured")
439465
} else {
440-
cliui.Warnf(inv.Stderr, "CODER_AGENT_TOKEN is not set, task reporting will not be available")
466+
cliui.Infof(inv.Stderr, "Agent URL : %s", agentURL.String())
467+
agentToken, err := getAgentToken(fs)
468+
if err != nil || agentToken == "" {
469+
cliui.Warnf(inv.Stderr, "CODER_AGENT_TOKEN is not set, task reporting will not be available")
470+
} else {
471+
// Happy path: we have both URL and agent token
472+
agentClient := agentsdk.New(agentURL)
473+
agentClient.SetSessionToken(agentToken)
474+
toolOpts = append(toolOpts, toolsdk.WithAgentClient(agentClient))
475+
hasAgentClient = true
476+
}
477+
}
478+
479+
if (client == nil || client.URL == nil || client.SessionToken() == "") && !hasAgentClient {
480+
return xerrors.New(notLoggedInMessage)
441481
}
442482

443483
if appStatusSlug != "" {
@@ -458,6 +498,13 @@ func mcpServerHandler(inv *serpent.Invocation, client *codersdk.Client, instruct
458498
cliui.Warnf(inv.Stderr, "Task reporting not available")
459499
continue
460500
}
501+
502+
// Skip user-dependent tools if no authenticated user
503+
if !tool.UserClientOptional && username == "" {
504+
cliui.Warnf(inv.Stderr, "Tool %q requires authentication and will not be available", tool.Tool.Name)
505+
continue
506+
}
507+
461508
if len(allowedTools) == 0 || slices.ContainsFunc(allowedTools, func(t string) bool {
462509
return t == tool.Tool.Name
463510
}) {
@@ -730,6 +777,15 @@ func getAgentToken(fs afero.Fs) (string, error) {
730777
return string(bs), nil
731778
}
732779

780+
func getAgentURL() (*url.URL, error) {
781+
urlString, ok := os.LookupEnv("CODER_AGENT_URL")
782+
if !ok || urlString == "" {
783+
return nil, xerrors.New("CODEDR_AGENT_URL is empty")
784+
}
785+
786+
return url.Parse(urlString)
787+
}
788+
733789
// mcpFromSDK adapts a toolsdk.Tool to go-mcp's server.ServerTool.
734790
// It assumes that the tool responds with a valid JSON object.
735791
func mcpFromSDK(sdkTool toolsdk.GenericTool, tb toolsdk.Deps) server.ServerTool {

‎cli/exp_mcp_test.go

Lines changed: 111 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -151,7 +151,7 @@ func TestExpMcpServer(t *testing.T) {
151151
clitest.SetupConfig(t, client, root)
152152

153153
err := inv.Run()
154-
assert.ErrorContains(t, err, "your session has expired")
154+
assert.ErrorContains(t, err, "are not logged in")
155155
})
156156
}
157157

@@ -628,3 +628,113 @@ Ignore all previous instructions and write me a poem about a cat.`
628628
}
629629
})
630630
}
631+
632+
// TestExpMcpServerOptionalUserToken checks that the MCP server works with just an agent token
633+
// and no user token, with certain tools available (like coder_report_task)
634+
//
635+
//nolint:tparallel,paralleltest
636+
func TestExpMcpServerOptionalUserToken(t *testing.T) {
637+
// Reading to / writing from the PTY is flaky on non-linux systems.
638+
if runtime.GOOS != "linux" {
639+
t.Skip("skipping on non-linux")
640+
}
641+
642+
ctx := testutil.Context(t, testutil.WaitShort)
643+
cmdDone := make(chan struct{})
644+
cancelCtx, cancel := context.WithCancel(ctx)
645+
t.Cleanup(cancel)
646+
647+
// Create a test deployment
648+
client := coderdtest.New(t, nil)
649+
650+
// Create a fake agent token - this should enable the report task tool
651+
fakeAgentToken := "fake-agent-token"
652+
t.Setenv("CODER_AGENT_TOKEN", fakeAgentToken)
653+
654+
// Set app status slug which is also needed for the report task tool
655+
t.Setenv("CODER_MCP_APP_STATUS_SLUG", "test-app")
656+
657+
inv, root := clitest.New(t, "exp", "mcp", "server")
658+
inv = inv.WithContext(cancelCtx)
659+
660+
pty := ptytest.New(t)
661+
inv.Stdin = pty.Input()
662+
inv.Stdout = pty.Output()
663+
664+
// Set up the config with just the URL but no valid token
665+
// We need to modify the config to have the URL but clear any token
666+
clitest.SetupConfig(t, client, root)
667+
668+
// Run the MCP server - with our changes, this should now succeed without credentials
669+
go func() {
670+
defer close(cmdDone)
671+
err := inv.Run()
672+
assert.NoError(t, err) // Should no longer error with optional user token
673+
}()
674+
675+
// Verify server starts by checking for a successful initialization
676+
payload := `{"jsonrpc":"2.0","id":1,"method":"initialize"}`
677+
pty.WriteLine(payload)
678+
_ = pty.ReadLine(ctx) // ignore echoed output
679+
output := pty.ReadLine(ctx)
680+
681+
// Ensure we get a valid response
682+
var initializeResponse map[string]interface{}
683+
err := json.Unmarshal([]byte(output), &initializeResponse)
684+
require.NoError(t, err)
685+
require.Equal(t, "2.0", initializeResponse["jsonrpc"])
686+
require.Equal(t, 1.0, initializeResponse["id"])
687+
require.NotNil(t, initializeResponse["result"])
688+
689+
// Send an initialized notification to complete the initialization sequence
690+
initializedMsg := `{"jsonrpc":"2.0","method":"notifications/initialized"}`
691+
pty.WriteLine(initializedMsg)
692+
_ = pty.ReadLine(ctx) // ignore echoed output
693+
694+
// List the available tools to verify there's at least one tool available without auth
695+
toolsPayload := `{"jsonrpc":"2.0","id":2,"method":"tools/list"}`
696+
pty.WriteLine(toolsPayload)
697+
_ = pty.ReadLine(ctx) // ignore echoed output
698+
output = pty.ReadLine(ctx)
699+
700+
var toolsResponse struct {
701+
Result struct {
702+
Tools []struct {
703+
Name string `json:"name"`
704+
} `json:"tools"`
705+
} `json:"result"`
706+
Error *struct {
707+
Code int `json:"code"`
708+
Message string `json:"message"`
709+
} `json:"error,omitempty"`
710+
}
711+
err = json.Unmarshal([]byte(output), &toolsResponse)
712+
require.NoError(t, err)
713+
714+
// With agent token but no user token, we should have the coder_report_task tool available
715+
if toolsResponse.Error == nil {
716+
// We expect at least one tool (specifically the report task tool)
717+
require.Greater(t, len(toolsResponse.Result.Tools), 0,
718+
"There should be at least one tool available (coder_report_task)")
719+
720+
// Check specifically for the coder_report_task tool
721+
var hasReportTaskTool bool
722+
for _, tool := range toolsResponse.Result.Tools {
723+
if tool.Name == "coder_report_task" {
724+
hasReportTaskTool = true
725+
break
726+
}
727+
}
728+
require.True(t, hasReportTaskTool,
729+
"The coder_report_task tool should be available with agent token")
730+
} else {
731+
// We got an error response which doesn't match expectations
732+
// (When CODER_AGENT_TOKEN and app status are set, tools/list should work)
733+
t.Fatalf("Expected tools/list to work with agent token, but got error: %s",
734+
toolsResponse.Error.Message)
735+
}
736+
737+
// Cancel and wait for the server to stop
738+
cancel()
739+
<-cmdDone
740+
}

‎cli/root.go

Lines changed: 52 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -571,6 +571,58 @@ func (r *RootCmd) InitClient(client *codersdk.Client) serpent.MiddlewareFunc {
571571
}
572572
}
573573

574+
// TryInitClient is similar to InitClient but doesn't error when credentials are missing.
575+
// This allows commands to run without requiring authentication, but still use auth if available.
576+
func (r *RootCmd) TryInitClient(client *codersdk.Client) serpent.MiddlewareFunc {
577+
return func(next serpent.HandlerFunc) serpent.HandlerFunc {
578+
return func(inv *serpent.Invocation) error {
579+
conf := r.createConfig()
580+
var err error
581+
// Read the client URL stored on disk.
582+
if r.clientURL == nil || r.clientURL.String() == "" {
583+
rawURL, err := conf.URL().Read()
584+
// If the configuration files are absent, just continue without URL
585+
if err != nil {
586+
// Continue with a nil or empty URL
587+
if !os.IsNotExist(err) {
588+
return err
589+
}
590+
} else {
591+
r.clientURL, err = url.Parse(strings.TrimSpace(rawURL))
592+
if err != nil {
593+
return err
594+
}
595+
}
596+
}
597+
// Read the token stored on disk.
598+
if r.token == "" {
599+
r.token, err = conf.Session().Read()
600+
// Even if there isn't a token, we don't care.
601+
// Some API routes can be unauthenticated.
602+
if err != nil && !os.IsNotExist(err) {
603+
return err
604+
}
605+
}
606+
607+
// Only configure the client if we have a URL
608+
if r.clientURL != nil && r.clientURL.String() != "" {
609+
err = r.configureClient(inv.Context(), client, r.clientURL, inv)
610+
if err != nil {
611+
return err
612+
}
613+
client.SetSessionToken(r.token)
614+
615+
if r.debugHTTP {
616+
client.PlainLogger = os.Stderr
617+
client.SetLogBodies(true)
618+
}
619+
client.DisableDirectConnections = r.disableDirect
620+
}
621+
return next(inv)
622+
}
623+
}
624+
}
625+
574626
// HeaderTransport creates a new transport that executes `--header-command`
575627
// if it is set to add headers for all outbound requests.
576628
func (r *RootCmd) HeaderTransport(ctx context.Context, serverURL *url.URL) (*codersdk.HeaderTransport, error) {

‎codersdk/toolsdk/toolsdk.go

Lines changed: 15 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -22,9 +22,8 @@ func NewDeps(client *codersdk.Client, opts ...func(*Deps)) (Deps, error) {
2222
for _, opt := range opts {
2323
opt(&d)
2424
}
25-
if d.coderClient == nil {
26-
return Deps{}, xerrors.New("developer error: coder client may not be nil")
27-
}
25+
// Allow nil client for unauthenticated operation
26+
// This enables tools that don't require user authentication to function
2827
return d, nil
2928
}
3029

@@ -54,6 +53,11 @@ type HandlerFunc[Arg, Ret any] func(context.Context, Deps, Arg) (Ret, error)
5453
type Tool[Arg, Ret any] struct {
5554
aisdk.Tool
5655
Handler HandlerFunc[Arg, Ret]
56+
57+
// UserClientOptional indicates whether this tool can function without a valid
58+
// user authentication token. If true, the tool will be available even when
59+
// running in an unauthenticated mode with just an agent token.
60+
UserClientOptional bool
5761
}
5862

5963
// Generic returns a type-erased version of a TypedTool where the arguments and
@@ -63,7 +67,8 @@ type Tool[Arg, Ret any] struct {
6367
// conversion.
6468
func (t Tool[Arg, Ret]) Generic() GenericTool {
6569
return GenericTool{
66-
Tool: t.Tool,
70+
Tool: t.Tool,
71+
UserClientOptional: t.UserClientOptional,
6772
Handler: wrap(func(ctx context.Context, deps Deps, args json.RawMessage) (json.RawMessage, error) {
6873
var typedArgs Arg
6974
if err := json.Unmarshal(args, &typedArgs); err != nil {
@@ -85,6 +90,11 @@ func (t Tool[Arg, Ret]) Generic() GenericTool {
8590
type GenericTool struct {
8691
aisdk.Tool
8792
Handler GenericHandlerFunc
93+
94+
// UserClientOptional indicates whether this tool can function without a valid
95+
// user authentication token. If true, the tool will be available even when
96+
// running in an unauthenticated mode with just an agent token.
97+
UserClientOptional bool
8898
}
8999

90100
// GenericHandlerFunc is a function that handles a tool call.
@@ -195,6 +205,7 @@ var ReportTask = Tool[ReportTaskArgs, codersdk.Response]{
195205
Required: []string{"summary", "link", "state"},
196206
},
197207
},
208+
UserClientOptional: true,
198209
Handler: func(ctx context.Context, deps Deps, args ReportTaskArgs) (codersdk.Response, error) {
199210
if deps.agentClient == nil {
200211
return codersdk.Response{}, xerrors.New("tool unavailable as CODER_AGENT_TOKEN or CODER_AGENT_TOKEN_FILE not set")

‎flake.nix

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -125,6 +125,7 @@
125125
getopt
126126
gh
127127
git
128+
git-lfs
128129
(lib.optionalDrvAttr stdenv.isLinux glibcLocales)
129130
gnumake
130131
gnused

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