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feat(cli): make MCP server work without user authentication (coder#17688)
Part of coder#17649 --- # Allow MCP server to run without authentication This PR enhances the MCP server to operate without requiring authentication, making it more flexible for environments where authentication isn't available or necessary. Key changes: - Replaced `InitClient` with `TryInitClient` to allow the MCP server to start without credentials - Added graceful handling when URL or authentication is missing - Made authentication status visible in server logs - Added logic to skip user-dependent tools when no authenticated user is present - Made the `coder_report_task` tool available with just an agent token (no user token required) - Added comprehensive tests to verify operation without authentication These changes allow the MCP server to function in more environments while still using authentication when available, improving flexibility for CI/CD and other automated environments.
1 parent 6ac1bd8 commit 29bce8d

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5 files changed

+253
-23
lines changed

5 files changed

+253
-23
lines changed

‎cli/exp_mcp.go

+74-18
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

+111-1
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

+52
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

+15-4
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

+1
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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