Securing Spring Boot Applications

Learn how to enable and configure security in a Vaadin Flow application using the built-in security helpers with Spring Boot.

Vaadin is fully compatible with the most-popular security solutions in the Java ecosystem, including but not limited to Spring Security, Java Authentication and Authorization Service (JAAS), and Apache Shiro.

Although you can choose the security framework you want to use, Vaadin Flow comes with built-in security helpers that are most convenient to implement with Spring Security. Using these built-in helpers with Spring Security makes it easier, faster, and safer to secure your Vaadin applications compared to using the Spring Security framework directly — or with any other security framework.

This guide focuses on enabling security using the built-in helpers in combination with Spring Boot and Spring Security. For instructions on using the built-in helpers in non-Spring projects, see this separate chapter.

Introduction

In a Spring Boot application, Vaadin Flow built-in security helpers enable a view-based access control mechanism with minimum Spring Security configuration. This view-based access control mechanism enables you to secure fully views in Vaadin Flow applications in a flexible way, based on different access level annotations. Specifically, the view-based access control mechanism uses the @AnonymousAllowed, @PermitAll, @RolesAllowed, and @DenyAll annotations on view classes to define the access control rules.

To enable the mechanism in a Vaadin Flow Spring Boot application without any security, add the following to the project if they don’t exist already:

A Login view;
Spring Security dependencies;
Log-out capability;
A security configuration class that extends VaadinWebSecurity; and
One of the following annotations on each view class: @AnonymousAllowed, @PermitAll, or @RolesAllowed.

A complete example project, including the source code from this document, is available at github.com/vaadin/flow-crm-tutorial.

Log-in View

Having a log-in view is a basic requirement of many authentication and authorization mechanisms, to be able to redirect anonymous users to that page before giving access to view any protected resources.

The log-in view should always be accessible by anonymous users.

@Route("login")
@PageTitle("Login")
@AnonymousAllowed
public class LoginView extends VerticalLayout implements BeforeEnterObserver {

    private LoginForm login = new LoginForm();

    public LoginView() {
        addClassName("login-view");
        setSizeFull();

        setJustifyContentMode(JustifyContentMode.CENTER);
        setAlignItems(Alignment.CENTER);

        login.setAction("login");

        add(new H1("Test Application"), login);
    }

    @Override
    public void beforeEnter(BeforeEnterEvent beforeEnterEvent) {
        if(beforeEnterEvent.getLocation()
            .getQueryParameters()
            .getParameters()
            .containsKey("error")) {
            login.setError(true);
        }
    }
}

This example uses Vaadin’s Login Form component for the sake of brevity in this implementation. However, there is no obligation to do so; implement your own log-in view, as you wish.

Spring Security Dependencies

To enable Spring Security, there are certain dependencies that should be added to the project. As this guide is based on Spring Boot, you should add the following dependency:

<dependencies>
    <!-- other dependencies -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-security</artifactId>
    </dependency>
    <!-- other dependencies -->
</dependencies>

Log-Out Capability

To handle log-out in web applications, you would typically use a log-out button. Here is a basic implementation of a log-out button shown on the header of the main layout:

public class MainLayout extends AppLayout {

    private SecurityService securityService;

    public MainLayout(@Autowired SecurityService securityService) {
        this.securityService = securityService;

        H1 logo = new H1("Vaadin CRM");
        logo.addClassName("logo");
        HorizontalLayout header;
        if (securityService.getAuthenticatedUser() != null) {
            Button logout = new Button("Logout", click ->
                    securityService.logout());
            header = new HorizontalLayout(logo, logout);
        } else {
            header = new HorizontalLayout(logo);
        }

        // Other page components omitted.

        addToNavbar(header);
    }
}

The method of getting the authenticated user and logging out the user may vary from application to application. Here’s a basic example of doing this with the Spring Security API:

@Component
public class SecurityService {

    private static final String LOGOUT_SUCCESS_URL = "/";

    public UserDetails getAuthenticatedUser() {
        SecurityContext context = SecurityContextHolder.getContext();
        Object principal = context.getAuthentication().getPrincipal();
        if (principal instanceof UserDetails) {
            return (UserDetails) context.getAuthentication().getPrincipal();
        }
        // Anonymous or no authentication.
        return null;
    }

    public void logout() {
        UI.getCurrent().getPage().setLocation(LOGOUT_SUCCESS_URL);
        SecurityContextLogoutHandler logoutHandler = new SecurityContextLogoutHandler();
        logoutHandler.logout(
                VaadinServletRequest.getCurrent().getHttpServletRequest(), null,
                null);
    }
}

Security Utilities

To access authenticated user details and to simplify logout handling, Vaadin provides an AuthenticationContext component, strictly integrated with Spring Security, that can be injected into views and services.

The AuthenticationContext by design does not implement java.io.Serializable, so Vaadin view fields referencing this object must be defined transient. The class exposes the following utility methods:

isAuthenticated() checks if a user is currently logged in. Spring Anonymous user is considered not authenticated.
getAuthenticatedUser(Class<U> userType) gets user details. If userType does not match the actual user implementation, the method throws a ClassCastException.
logout initiates the Spring Security logout process and redirects the user to the configured logout URL.

Here’s an example implementation of a log-out button shown on the header of the main layout that uses the AuthenticationContext component:

public class MainLayout extends AppLayout {

    private final transient AuthenticationContext authContext;

    public MainLayout(AuthenticationContext authContext) {
        this.authContext = authContext;

        H1 logo = new H1("Vaadin CRM");
        logo.addClassName("logo");
        HorizontalLayout
        header =
        authContext.getAuthenticatedUser(UserDetails.class)
                .map(user -> {
                    Button logout = new Button("Logout", click ->
                            this.authContext.logout());
                    Span loggedUser = new Span("Welcome " + user.getUsername());
                    return new HorizontalLayout(logo, loggedUser, logout);
                }).orElseGet(() -> new HorizontalLayout(logo));

        // Other page components omitted.

        addToNavbar(header);
    }
}

Security Configuration Class

The next step is to have a Spring Security class that extends VaadinWebSecurity. There’s no convention for naming this class, so in this documentation it’s named SecurityConfiguration. However, take care with Spring Security annotations.

Here is a minimal implementation of such a class:

@EnableWebSecurity // (1)
@Configuration
public class SecurityConfiguration
                extends VaadinWebSecurity { // (2)

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        // Delegating the responsibility of general configurations
        // of http security to the super class. It's configuring
        // the followings: Vaadin's CSRF protection by ignoring
        // framework's internal requests, default request cache,
        // ignoring public views annotated with @AnonymousAllowed,
        // restricting access to other views/endpoints, and enabling
        // ViewAccessChecker authorization.
        // You can add any possible extra configurations of your own
        // here (the following is just an example):

        // http.rememberMe().alwaysRemember(false);

        // Configure your static resources with public access before calling
        // super.configure(HttpSecurity) as it adds final anyRequest matcher
        http.authorizeHttpRequests().requestMatchers(new AntPathRequestMatcher("/public/**"))
            .permitAll();

        super.configure(http); // (3)

        // This is important to register your login view to the
        // view access checker mechanism:
        setLoginView(http, LoginView.class); // (4)
    }

    @Override
    public void configure(WebSecurity web) throws Exception {
        // Customize your WebSecurity configuration.
        super.configure(web);
    }

    /**
     * Demo UserDetailsManager which only provides two hardcoded
     * in memory users and their roles.
     * NOTE: This shouldn't be used in real world applications.
     */
    @Bean
    public UserDetailsManager userDetailsService() {
        UserDetails user =
                User.withUsername("user")
                        .password("{noop}user")
                        .roles("USER")
                        .build();
        UserDetails admin =
                User.withUsername("admin")
                        .password("{noop}admin")
                        .roles("ADMIN")
                        .build();
        return new InMemoryUserDetailsManager(user, admin);
    }
}

Notice the presence of @EnableWebSecurity and @Configuration annotations on top of the above class. As their names imply, they tell Spring to enable its security features.

VaadinWebSecurity is a helper class that configures the common Vaadin-related Spring security settings. By extending it, the view-based access control mechanism is enabled automatically, and no further configuration is needed to enable it. Other benefits are covered as follows.

The default implementation of the configure methods takes care of all of the Vaadin-related configuration. For example, it ignores static resources, or enables CSRF checking, while ignoring unnecessary checking for Vaadin internal requests, etc.

The log-in view can be configured via the provided setLoginView() method.

Warning

Never use hard-coded credentials in production

The implementation of the userDetailsService() method is just an in-memory implementation for the sake of brevity in this documentation. In a normal application, you can change the Spring Security configuration to use an authentication provider for Lightweight Directory Access Protocol (LDAP), JAAS, and other real-world sources. Read more about Spring Security authentication providers.

The most important configuration in the previous example is the call to setLoginView(http, LoginView.class) inside the first configure method. This is how the view-based access control mechanism knows where to redirect users when they try to navigate to a protected view.

The log-in view should always be accessible by anonymous users, so it should have the @AnonymousAllowed annotation. This is especially important when using the variant of the setLoginView method where you provide the route path — although this signature is meant to be used with Hilla views, not with Flow views.

Note	Component-based security configuration Spring Security 5.7.0 deprecates the `WebSecurityConfigurerAdapter` and encourages users to move towards a component-based security configuration.

VaadinWebSecurityConfigurerAdapter is still available for Vaadin 23.2 users, although it’s recommended to use component-based security configuration as in SecurityConfiguration example here. Read more about updating from WebSecurityConfigurerAdapter to component-based security configuration.

Once the LoginView is ready, and it’s set as the log-in view in the security configuration, it’s time to move forward and see how the security annotations work on the views.

Annotating the View Classes

Before providing some usage examples of access annotations, it would be useful to have a closer look at the annotations and their meaning when applied to a view:

@AnonymousAllowed permits anyone to navigate to the view without any authentication or authorization.
@PermitAll allows any authenticated user to navigate to the view.
@RolesAllowed grants access to users having the roles specified in the annotation value.
@DenyAll disallows everyone from navigating to the view. This is the default, which means that if a view isn’t annotated at all, the @DenyAll logic is applied.

When the security configuration class extends from VaadinWebSecurityConfigurerAdapter, Vaadin’s SpringSecurityAutoConfiguration comes into play and enables the view-based access control mechanism. Therefore, none of the views are accessible until one of these annotations is applied to them — except @DenyAll.

Examples

Using @AnonymousAllowed to enable all users to navigate to this view:

@Route(value = "", layout = MainView.class)
@PageTitle("Public View")
@AnonymousAllowed
public class PublicView extends VerticalLayout {
    // ...
}

Using @PermitAll to allow only authenticated users — with any role — to navigate to this view:

@Route(value = "private", layout = MainView.class)
@PageTitle("Private View")
@PermitAll
public class PrivateView extends VerticalLayout {
    // ...
}

Using @RolesAllowed to enable only the users with ADMIN role to navigate to this view:

@Route(value = "admin", layout = MainView.class)
@PageTitle("Admin View")
@RolesAllowed("ADMIN") // <- Should match one of the user's roles (case-sensitive)
public class AdminView extends VerticalLayout {
    // ...
}

Inheriting security annotations from parent class:

@RolesAllowed("ADMIN")
public abstract class AbstractAdminView extends VerticalLayout {
    // ...
}

@Route(value = "user-listing", layout = MainView.class)
@PageTitle("User Listing")
public class UserListingView extends AbstractAdminView {
    // ...
}

Annotation Inheritance and Overrides

As shown in the last example, the security annotations are inherited from the closest parent class that has them. Annotating a child class overrides any inherited annotations. Interfaces aren’t checked for annotations, only classes.

By design, the annotations aren’t read from parent layouts or "parent views", as this would make it unnecessarily complex to determine which security level should be applied. If multiple annotations are specified on a single view class, the following rules are applied:

DenyAll overrides other annotations;
AnonymousAllowed overrides RolesAllowed and PermitAll; and
RolesAllowed overrides PermitAll.

However, specifying more than one of the above access annotations on a view class isn’t recommended. Besides the fact that there’s probably no logical reason to do so, it would be confusing.

Error Messages for Unauthorized Views

If the user is already authenticated and tries to navigate to a view for which they don’t have permission, an error message is displayed. The message depends on the application mode.

In development mode, Vaadin shows an Access denied message with a list of available routes. In production mode, Vaadin shows the RouteNotFoundError view, which shows a Could not navigate to 'RequestedRouteName' message by default. For security reasons, the message doesn’t say whether the navigation target exists.

Limitations

Mixing any of the view access annotations with Spring’s URL-based HTTP security — which possibly exists in older Vaadin Spring Boot applications — may result in unwanted access configurations or unnecessary complications.

Important

Don’t mix Spring’s URL-based HTTP security and view-based access control on a single view.

Vaadin strongly recommends not to mix Spring’s URL-pattern-based HTTP security and this view-based access control mechanism targeting the same views. Doing so might cause unwanted access configurations, and would be an unnecessary complication in the authorization of views.

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