fix: use backend for /healthz page (#4938)

coderd/coderd.go

@@ -233,6 +233,8 @@ func New(options *Options) *API {
 		httpmw.CSRF(options.SecureAuthCookie),
 	)
 
+	r.Get("/healthz", func(w http.ResponseWriter, r *http.Request) { _, _ = w.Write([]byte("OK")) })
+
 	apps := func(r chi.Router) {
 		r.Use(
 			tracing.Middleware(api.TracerProvider),

coderd/coderd_test.go

@@ -2,6 +2,7 @@ package coderd_test
 
 import (
 	"context"
+	"io"
 	"net/http"
 	"net/netip"
 	"strconv"
@@ -114,3 +115,17 @@ func TestDERPLatencyCheck(t *testing.T) {
 	defer res.Body.Close()
 	require.Equal(t, http.StatusOK, res.StatusCode)
 }
+func TestHealthz(t *testing.T) {
+	t.Parallel()
+	client := coderdtest.New(t, nil)
+
+	res, err := client.Request(context.Background(), http.MethodGet, "/healthz", nil)
+	require.NoError(t, err)
+	defer res.Body.Close()
+
+	require.Equal(t, http.StatusOK, res.StatusCode)
+	body, err := io.ReadAll(res.Body)
+	require.NoError(t, err)
+
+	assert.Equal(t, "OK", string(body))
+}

coderd/coderdtest/authorize.go

@@ -37,6 +37,7 @@ func AGPLRoutes(a *AuthTester) (map[string]string, map[string]RouteCheck) {
 
 	assertRoute := map[string]RouteCheck{
 		// These endpoints do not require auth
+		"GET:/healthz":                  {NoAuthorize: true},
 		"GET:/api/v2":                   {NoAuthorize: true},
 		"GET:/api/v2/buildinfo":         {NoAuthorize: true},
 		"GET:/api/v2/users/first":       {NoAuthorize: true},

site/src/AppRouter.tsx

@@ -30,7 +30,6 @@ const NotFoundPage = lazy(() => import("./pages/404Page/404Page"))
 const CliAuthenticationPage = lazy(
   () => import("./pages/CliAuthPage/CliAuthPage"),
 )
-const HealthzPage = lazy(() => import("./pages/HealthzPage/HealthzPage"))
 const AccountPage = lazy(
   () => import("./pages/UserSettingsPage/AccountPage/AccountPage"),
 )
@@ -107,7 +106,6 @@ export const AppRouter: FC = () => {
 
         <Route path="login" element={<LoginPage />} />
         <Route path="setup" element={<SetupPage />} />
-        <Route path="healthz" element={<HealthzPage />} />
         <Route
           path="cli-auth"
           element={