sec: disable email and password signup

cmd/web/handlers:login.go

@@ -45,20 +45,41 @@ func (app *application) redirectAfterLogin(ctx context.Context, w http.ResponseW
 	}
 }
 
+type signInData struct {
+	OIDCProviders             []string
+	EnableEmailPasswordSignup bool
+}
+
 func (app *application) getSignIn(w http.ResponseWriter, r *http.Request) *httperr.Error {
+	names := make([]string, 0, len(app.oidcProviders))
+	for name := range app.oidcProviders {
+		names = append(names, name)
+	}
+
 	tmplData := app.html.TemplateData(r)
 	tmplData.Form = accounts.NewSignInForm()
-	tmplData.Data = app.loginData()
+	tmplData.Data = signInData{
+		EnableEmailPasswordSignup: app.options.EnableEmailPasswordSignup,
+		OIDCProviders:             names,
+	}
 	return app.html.Render(w, r, http.StatusOK, pages.SignIn, tmplData)
 }
 
 func (app *application) postSignIn(w http.ResponseWriter, r *http.Request) *httperr.Error {
 	ctx := r.Context()
 
 	fail := func(formWithErrors *accounts.SignInForm) *httperr.Error {
+		names := make([]string, 0, len(app.oidcProviders))
+		for name := range app.oidcProviders {
+			names = append(names, name)
+		}
+
 		data := app.html.TemplateData(r)
 		data.Form = formWithErrors
-		data.Data = app.loginData()
+		data.Data = signInData{
+			EnableEmailPasswordSignup: app.options.EnableEmailPasswordSignup,
+			OIDCProviders:             names,
+		}
 		return app.html.Render(w, r, http.StatusUnprocessableEntity, pages.SignIn, data)
 	}
 
@@ -263,20 +284,6 @@ func (app *application) postSignOut(w http.ResponseWriter, r *http.Request) *htt
 	return nil
 }
 
-// LoginData carries the set of enabled OIDC provider names to the sign-in and
-// sign-up templates so they can render the appropriate provider buttons.
-type LoginData struct {
-	OIDCProviders []string
-}
-
-func (app *application) loginData() LoginData {
-	names := make([]string, 0, len(app.oidcProviders))
-	for name := range app.oidcProviders {
-		names = append(names, name)
-	}
-	return LoginData{OIDCProviders: names}
-}
-
 // getAuthOIDC initiates the OIDC login flow for the named provider. It generates
 // a random state token, stores it in the session for CSRF verification, then
 // redirects the browser to the provider's authorization endpoint.

cmd/web/options.go

@@ -34,6 +34,11 @@ type options struct {
 	SMTP          SMTP            // has SECRET
 	OIDCProviders OIDCProviderMap // has SECRET
 	Limits        Limits
+
+	// EnableEmailPasswordSignup controls whether users can sign up with email and password.
+	// Selfhosters can signup once to create an account and then disable email password signup
+	// to prevent further unwanted signups.
+	EnableEmailPasswordSignup bool
 }
 
 func parseOptions(args []string) (*options, error) {
@@ -60,6 +65,8 @@ func parseOptions(args []string) (*options, error) {
 	fs.StringVar(&cfg.SMTP.Password, "smtp-password", envOr("SMTP_PASSWORD", ""), "SMTP password (prefer SMTP_PASSWORD env var over flag)")
 	fs.StringVar(&cfg.SMTP.From, "smtp-from", "", "from address for outgoing mail")
 
+	fs.BoolVar(&cfg.EnableEmailPasswordSignup, "enable-email-password-signup", true, "enable email and password signup (default true)")
+
 	if err := fs.Parse(args); err != nil {
 		return nil, fmt.Errorf("parseServeOptions: %w", err)
 	}

cmd/web/routes.go

@@ -50,8 +50,10 @@ func (app *application) routes() (http.Handler, error) {
 	// Login related routes that are only accessible if the user is not logged in.
 	mux.Handle("GET /signin", app.withGuest(app.html.Handle(app.getSignIn)))
 	mux.Handle("POST /signin", app.withGuest(app.html.Handle(app.postSignIn)))
-	mux.Handle("GET /signup", app.withGuest(app.html.Handle(app.getSignUp)))
-	mux.Handle("POST /signup", app.withGuest(app.html.Handle(app.postSignUp)))
+	if app.options.EnableEmailPasswordSignup {
+		mux.Handle("GET /signup", app.withGuest(app.html.Handle(app.getSignUp)))
+		mux.Handle("POST /signup", app.withGuest(app.html.Handle(app.postSignUp)))
+	}
 	mux.Handle("GET /forgot-password", app.withGuest(app.html.Handle(app.getForgotPassword)))
 	mux.Handle("POST /forgot-password", app.withGuest(app.html.Handle(app.postForgotPassword)))
 	mux.Handle("GET /forgot-password/success", app.withGuest(app.html.Handle(app.getForgotPasswordSuccess)))

internal/templates/pages/docs.tmpl

@@ -289,6 +289,12 @@
             <td><code class="font-mono text-xs">error</code></td>
             <td><code class="font-mono text-xs">debug</code>, <code class="font-mono text-xs">info</code>, <code class="font-mono text-xs">warn</code>, <code class="font-mono text-xs">error</code></td>
           </tr>
+          <tr>
+            <td class="w-full"><code class="badge badge-neutral font-mono">-enable-email-password-signup</code></td>
+            <td>—</td>
+            <td><code class="font-mono text-xs">true</code></td>
+            <td>enable email and password signup (default true)</td>
+          </tr>
 
           <tr class="bg-base-200/50">
             <td colspan="4" class="text-xs uppercase tracking-wider py-1">

internal/templates/pages/login/signin.tmpl

@@ -80,10 +80,12 @@
       {{ end }}
       {{ end }}
 
+      {{ if .Data.EnableEmailPasswordSignup }}
       <p class="label justify-center">
         Don't have an account?
         <a href="/signup" class="link link-hover">Sign up.</a>
       </p>
+      {{ end }}
     </fieldset>
   </form>
 </div>