fix(ingestion): build /mcp's bearer and the metrics wrap inside buildMux (#154) #183

Merged
mathias merged 2 commits from w3/154-mcp-auth-wiring into main 2026-10-05 17:48:44 +00:00
5 changed files with 109 additions and 53 deletions
Showing only changes of commit 4a1abafd8f - Show all commits
+4 -1
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@@ -12,6 +12,8 @@ import (
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
"github.com/mathiasbq/hyperguild/ingestion/internal/metrics"
)
// fakeIssuer answers OIDC discovery with 502 for the first fail requests, as
@@ -73,7 +75,8 @@ func TestBuildMuxAnswers503ToAJWTWhileTheIssuerIsUnresolved(t *testing.T) {
srv, _ := fakeIssuer(t, 1000)
v, err := buildJWTValidator(context.Background(), slog.New(slog.DiscardHandler), srv.URL, "brain")
require.NoError(t, err)
mux, err := buildMux(restAuth{token: routesTok, validator: v, realm: "brain"}, testHandler(t), nil)
mux, err := buildMux(restAuth{token: routesTok, validator: v, realm: "brain"}, testHandler(t),
okHandler("mcp"), metrics.New(), nil)
require.NoError(t, err)
code, _ := do(t, mux, "GET", "/pending", "Bearer aaa.bbb.ccc")
assert.Equal(t, http.StatusServiceUnavailable, code)
+12 -17
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@@ -516,8 +516,6 @@ func main() {
}
}
public["/mcp"] = chassisauth.BearerMiddleware(mcpToken, jwtValidator, "brain", resourceMetadataURL, mcpSrv)
// POST /capture (#53/#54): the uniform capture REST door. Needs a ticket
// tracker to file action items, so it only mounts when Gitea is
// configured. It reuses the MCP server's graph-wired brain store (one
@@ -541,7 +539,7 @@ func main() {
public["POST /capture"] = captureH
// Same use-case behind the MCP `capture` tool (#55 relay) so MCP-native
// harnesses (claude.ai, Crush, Pi, LLM Council) reach capture through
// the existing /mcp OAuth connector. mcpSrv is already wrapped above;
// the existing /mcp OAuth connector. buildMux wraps this same mcpSrv;
// WithCapture mutates the same instance, so the tool appears live.
mcpSrv.WithCapture(captureSvc, jwtValidator, mcpToken, "local-cli", resolver)
// hyperguild#97: a governance-file rewrite gets the same trail a
@@ -583,19 +581,16 @@ func main() {
os.Exit(1)
}
// /metrics — unauthenticated Prometheus endpoint. kube-prometheus-stack
// scrapes it via the ServiceMonitor in k3s/apps/supervisor/. The metrics
// middleware below wraps every other registered handler so it observes
// real request latency. /metrics itself is excluded from its own
// observation by registering it on the outer mux (post-wrap).
reg := metrics.New()
public["GET /metrics"] = http.HandlerFunc(reg.Handler())
// The whole router, built in one place so the test of buildMux is a test
// of production wiring (PR #152 review). The REST API's credential is the
// same as /mcp's.
mux, err := buildMux(restAuth{token: mcpToken, validator: jwtValidator, realm: "brain",
resourceMetadataURL: resourceMetadataURL}, h, public)
// /metrics — unauthenticated Prometheus endpoint, scraped via the
// ServiceMonitor in k3s/apps/supervisor/. buildMux registers it and wraps
// the whole router in the registry's middleware.
//
// The whole router, /mcp's bearer included, is built in buildMux so its
// tests are tests of production wiring (PR #152 review, hyperguild#154).
// The REST API's credential is the same as /mcp's. ListenAndServe below
// must serve its result unchanged: that one line is the untested part.
handler, err := buildMux(restAuth{token: mcpToken, validator: jwtValidator, realm: "brain",
resourceMetadataURL: resourceMetadataURL}, h, mcpSrv, metrics.New(), public)
if err != nil {
logger.Error("build router", "err", err)
os.Exit(1)
@@ -616,7 +611,7 @@ func main() {
"watch_interval", watchIntervalLog,
"mcp_enabled", true,
)
if err := http.ListenAndServe(addr, reg.Middleware(mux)); err != nil {
if err := http.ListenAndServe(addr, handler); err != nil {
logger.Error("server stopped", "err", err)
os.Exit(1)
}
+31 -18
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@@ -8,22 +8,22 @@ import (
chassisauth "git.d-ma.be/mathias/mcp-chassis/auth"
"github.com/mathiasbq/hyperguild/ingestion/internal/api"
"github.com/mathiasbq/hyperguild/ingestion/internal/metrics"
)
// publicRoutes is the complete set of patterns allowed on the outer mux,
// outside the REST API's auth (hyperguild#149). Each authenticates itself or is
// meant to be open: /mcp (bearer/JWT), /capture (bearer/JWT), the webhook
// (HMAC), /oauth/token (client secret), OAuth metadata and /metrics (open).
// A REST pattern added here would beat the authenticated catch-all by
// specificity and ship open, which is why buildMux refuses anything else.
// publicRoutes is the complete set of patterns a caller may register on the
// outer mux, outside the REST API's auth (hyperguild#149). Each authenticates
// itself or is meant to be open: /capture (bearer/JWT), the webhook (HMAC),
// /oauth/token (client secret) and OAuth metadata (open). /mcp and /metrics
// are not here: buildMux builds them itself (hyperguild#154). A REST pattern
// added here would beat the authenticated catch-all by specificity and ship
// open, which is why buildMux refuses anything else.
var publicRoutes = map[string]bool{
"/mcp": true,
"POST /capture": true,
"POST /webhooks/brain-sync": true,
"GET /.well-known/oauth-protected-resource": true,
"GET /.well-known/oauth-authorization-server": true,
"POST /oauth/token": true,
"GET /metrics": true,
}
// restAuth is the credential the REST API checks: the same as /mcp's.
@@ -34,16 +34,24 @@ type restAuth struct {
resourceMetadataURL string
}
// buildMux is the server's whole router. The REST API is mounted at "/"
// behind bearer auth that buildMux constructs itself, so a caller cannot pass
// a no-op; public handlers are registered as given, and only for patterns on
// the publicRoutes allowlist. It returns an http.Handler, not the
// *ServeMux, so nothing can register a route on the result afterwards and
// bypass the allowlist.
func buildMux(auth restAuth, h *api.Handler, public map[string]http.Handler) (http.Handler, error) {
// buildMux builds the handler main passes to ListenAndServe unchanged. The
// REST API is mounted at "/" and /mcp is registered, both behind bearer auth
// that buildMux constructs itself from auth (one credential), so a caller
// cannot pass a no-op. GET /metrics serves reg, and the whole router is
// wrapped in reg's middleware. Other public handlers are registered as given,
// and only for patterns on the publicRoutes allowlist. It returns an
// http.Handler, not the *ServeMux, so nothing can register a route on the
// result. What stays untested is main's own line: a handler main built around
// this one before ListenAndServe would not be seen by these tests.
func buildMux(
auth restAuth, h *api.Handler, mcpHandler http.Handler, reg *metrics.Registry, public map[string]http.Handler,
) (http.Handler, error) {
if auth.token == "" {
return nil, errors.New("buildMux: REST auth needs a token")
}
if mcpHandler == nil || reg == nil {
return nil, errors.New("buildMux: needs the MCP handler and the metrics registry")
}
mux := http.NewServeMux()
for pattern, handler := range public {
if !publicRoutes[pattern] {
@@ -51,10 +59,15 @@ func buildMux(auth restAuth, h *api.Handler, public map[string]http.Handler) (ht
}
mux.Handle(pattern, handler)
}
mountREST(mux, h, func(next http.Handler) http.Handler {
bearer := func(next http.Handler) http.Handler {
return chassisauth.BearerMiddleware(auth.token, auth.validator, auth.realm, auth.resourceMetadataURL, next)
})
return mux, nil
}
mux.Handle("/mcp", bearer(mcpHandler))
// /metrics is registered on the mux and so observed by its own
// middleware, like any route.
mux.Handle("GET /metrics", reg.Handler())
mountREST(mux, h, bearer)
return reg.Middleware(mux), nil
}
// mountREST registers the REST API on its own mux and mounts it at "/" behind
@@ -9,8 +9,6 @@ import (
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
"github.com/mathiasbq/hyperguild/ingestion/internal/metrics"
)
// wrongTokSentinel is a presented credential distinctive enough that any
@@ -53,8 +51,8 @@ func TestBuildMuxAcceptedLogLineOmitsTheBareStaticToken(t *testing.T) {
// An authenticated REST request is labelled with the REST mux's pattern:
// the inner mux sets it on the same *http.Request the outer middleware reads.
func TestMetricsLabelAnAuthenticatedRESTRequestWithItsRoutePattern(t *testing.T) {
reg := metrics.New()
code, _ := do(t, reg.Middleware(testMux(t)), "GET", "/pending", "Bearer "+routesTok)
mux, reg := testMuxAndRegistry(t)
code, _ := do(t, mux, "GET", "/pending", "Bearer "+routesTok)
require.Equal(t, http.StatusOK, code)
rec := httptest.NewRecorder()
@@ -67,8 +65,8 @@ func TestMetricsLabelAnAuthenticatedRESTRequestWithItsRoutePattern(t *testing.T)
// so it was labelled path="/" and a 4xx on /query could not be told from one
// on /write. It is now labelled with the REST pattern it was addressed to.
func TestMetricsLabelARejectedRESTRequestWithItsRoutePattern(t *testing.T) {
reg := metrics.New()
code, _ := do(t, reg.Middleware(testMux(t)), "POST", "/query", "")
mux, reg := testMuxAndRegistry(t)
code, _ := do(t, mux, "POST", "/query", "")
require.Equal(t, http.StatusUnauthorized, code)
rec := httptest.NewRecorder()
@@ -79,8 +77,8 @@ func TestMetricsLabelARejectedRESTRequestWithItsRoutePattern(t *testing.T) {
// A path no REST route matches keeps the catch-all label, so an attacker
// probing random URLs cannot grow the series set.
func TestMetricsLabelARejectedUnknownPathWithTheCatchAll(t *testing.T) {
reg := metrics.New()
code, _ := do(t, reg.Middleware(testMux(t)), "POST", "/no-such-route-zq", "")
mux, reg := testMuxAndRegistry(t)
code, _ := do(t, mux, "POST", "/no-such-route-zq", "")
require.Equal(t, http.StatusUnauthorized, code)
rec := httptest.NewRecorder()
+56 -9
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@@ -12,6 +12,7 @@ import (
"github.com/stretchr/testify/require"
"github.com/mathiasbq/hyperguild/ingestion/internal/api"
"github.com/mathiasbq/hyperguild/ingestion/internal/metrics"
"github.com/mathiasbq/hyperguild/ingestion/internal/pipeline"
)
@@ -22,19 +23,26 @@ func okHandler(body string) http.Handler {
}
// testMux builds the router exactly as main does: buildMux with the full
// public set main registers (stub handlers) and real bearer config.
// hyperguild#149: the REST API is authenticated as a whole; the PR #152
// review showed a test of a COPY of the router let main.go regress unseen.
// public set main registers (stub handlers), a stub MCP server, and real
// bearer config. hyperguild#149: the REST API is authenticated as a whole;
// the PR #152 review showed a test of a COPY of the router let main.go
// regress unseen.
func testMux(t *testing.T) http.Handler {
t.Helper()
h := testHandler(t)
mux, _ := testMuxAndRegistry(t)
return mux
}
func testMuxAndRegistry(t *testing.T) (http.Handler, *metrics.Registry) {
t.Helper()
public := map[string]http.Handler{}
for p := range publicRoutes {
public[p] = okHandler("public " + p)
}
mux, err := buildMux(restAuth{token: routesTok, realm: "brain"}, h, public)
reg := metrics.New()
mux, err := buildMux(restAuth{token: routesTok, realm: "brain"}, testHandler(t), okHandler("mcp"), reg, public)
require.NoError(t, err)
return mux
return mux, reg
}
func testHandler(t *testing.T) *api.Handler {
@@ -98,14 +106,53 @@ func TestBuildMuxDoesNotWrapPublicRoutes(t *testing.T) {
// over the authenticated catch-all (more specific pattern), so it is refused.
func TestBuildMuxRefusesAPublicPatternOffTheAllowlist(t *testing.T) {
h := api.NewHandler(t.TempDir(), slog.New(slog.NewTextHandler(os.Stderr, nil)), pipeline.Config{})
for _, p := range []string{"POST /query", "GET /pending", "/", "POST /metrics"} {
_, err := buildMux(restAuth{token: routesTok, realm: "brain"}, h, map[string]http.Handler{p: okHandler("x")})
// "/mcp" and "GET /metrics" are built by buildMux itself (hyperguild#154):
// passing either as public would register them unauthenticated or twice.
for _, p := range []string{"POST /query", "GET /pending", "/", "POST /metrics", "/mcp", "GET /metrics"} {
_, err := buildMux(restAuth{token: routesTok, realm: "brain"}, h, okHandler("mcp"), metrics.New(),
map[string]http.Handler{p: okHandler("x")})
assert.Error(t, err, "public pattern %q must be refused", p)
}
}
func TestBuildMuxRefusesAnEmptyToken(t *testing.T) {
h := api.NewHandler(t.TempDir(), slog.New(slog.NewTextHandler(os.Stderr, nil)), pipeline.Config{})
_, err := buildMux(restAuth{token: "", realm: "brain"}, h, nil)
_, err := buildMux(restAuth{token: "", realm: "brain"}, h, okHandler("mcp"), metrics.New(), nil)
assert.Error(t, err)
}
// hyperguild#154: /mcp's bearer was built in main.go, untested; the buildMux
// tests used stubs. buildMux now wraps the MCP handler itself, with the same
// credential as the REST API.
func TestBuildMuxRefusesMCPWithoutAValidToken(t *testing.T) {
r := testMux(t)
for _, authz := range []string{"", "Bearer wrong"} {
code, body := do(t, r, "POST", "/mcp", authz)
assert.Equal(t, http.StatusUnauthorized, code, "authz %q", authz)
assert.NotEqual(t, "mcp", body)
}
code, body := do(t, r, "POST", "/mcp", "Bearer "+routesTok)
assert.Equal(t, http.StatusOK, code)
assert.Equal(t, "mcp", body)
}
func TestBuildMuxRefusesANilMCPHandlerOrRegistry(t *testing.T) {
auth := restAuth{token: routesTok, realm: "brain"}
_, err := buildMux(auth, testHandler(t), nil, metrics.New(), nil)
assert.Error(t, err)
_, err = buildMux(auth, testHandler(t), okHandler("mcp"), nil, nil)
assert.Error(t, err)
}
// hyperguild#154: main wrapped buildMux's result in the metrics middleware
// before ListenAndServe, untested. buildMux now returns the handler main
// serves as-is, metrics included: a request through it is observed and
// exposed on its own GET /metrics.
func TestBuildMuxObservesRequestsAndServesMetrics(t *testing.T) {
r := testMux(t)
code, _ := do(t, r, "GET", "/pending", "Bearer "+routesTok)
require.Equal(t, http.StatusOK, code)
code, body := do(t, r, "GET", "/metrics", "")
require.Equal(t, http.StatusOK, code)
assert.Contains(t, body, `path="GET /pending"`)
}