How to implement multi-tenancy in new Spring Authorization server

Question

Link for Authorization server: https://github.com/spring-projects/spring-authorization-server

This project pretty much has everything in terms of OAuth and Identity provider. My question is, How to achieve multi-tenancy at the Identity provider level.

I know there are multiple ways to achieve multi-tenancy in general.

The scenario I am interested in is this:

1. An organization provides services to multiple tenants.
2. Each tenant is associated with a separate database (Data isolation including user data)
3. When a user visits dedicated Front-end app(per tenant) and negotiate access tokens from Identity provider
4. Identity provider then identifies tenant (Based on header/ Domain name) and generates access token with tenant_id
5. This access token then is passed on to down-stream services, which intern can extract tenant_id and decide the data source

I have a general idea about all the above steps, but I am not sure about point 4.

I am not sure How to configure different data sources for different tenants on the Identity Provider? How to add tenant_id in Token?

Link to the issue: https://github.com/spring-projects/spring-authorization-server/issues/663#issue-1182431313

Answer 1

This is really a good question and I really want to know how to do it in new Authorization Server in a proper way. In Spring Resource Server there is a section about Multitenancy. I did it successfully.

As far as new Spring Authorization Server multitenancy concerns. I have also done it for the password and the Client Credentials grant type.

But please note that although it is working but how perfect is this. I don't know because I just did it for learning purpose. It's just a sample. I will also post it on my github when I would do it for the authorization code grant type.

I am assuming that the master and tenant database configuration has been done. I can not provide the whole code here because it's lot of code. I will just provide the relevant snippets. But here is just the sample

@Configuration
@Import({MasterDatabaseConfiguration.class, TenantDatabaseConfiguration.class})
public class DatabaseConfiguration {
    
}

I used the separate database. What I did I used something like the following in the AuthorizationServerConfiguration.

@Import({OAuth2RegisteredClientConfiguration.class})
public class AuthorizationServerConfiguration {
    @Bean
    @Order(Ordered.HIGHEST_PRECEDENCE)
    public SecurityFilterChain authorizationServerSecurityFilterChain(HttpSecurity http) throws Exception {
        OAuth2AuthorizationServerConfigurer<HttpSecurity> authorizationServerConfigurer = new OAuth2AuthorizationServerConfigurer<>();
        ....
        http.addFilterBefore(new TenantFilter(), OAuth2AuthorizationRequestRedirectFilter.class);
    
        SecurityFilterChain securityFilterChain = http.formLogin(Customizer.withDefaults()).build();

        addCustomOAuth2ResourceOwnerPasswordAuthenticationProvider(http);
        return securityFilterChain;
    }
}

Here is my TenantFilter code

public class TenantFilter extends OncePerRequestFilter {

    private static final Logger LOGGER = LogManager.getLogger();

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
    
        String requestUrl = request.getRequestURL().toString();
    
        if (!requestUrl.endsWith("/oauth2/jwks")) {
            String tenantDatabaseName = request.getParameter("tenantDatabaseName");
            if(StringUtils.hasText(tenantDatabaseName)) {
                LOGGER.info("tenantDatabaseName request parameter is found");
                TenantDBContextHolder.setCurrentDb(tenantDatabaseName);
            } else {
                LOGGER.info("No tenantDatabaseName request parameter is found");
                response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
                response.setContentType(MediaType.APPLICATION_JSON_VALUE);
                response.getWriter().write("{'error': 'No tenant request parameter supplied'}");
                response.getWriter().flush();
                return;
            }
        }
    
        filterChain.doFilter(request, response);
    
    }

    public static String getFullURL(HttpServletRequest request) {
        StringBuilder requestURL = new StringBuilder(request.getRequestURL().toString());
        String queryString = request.getQueryString();

        if (queryString == null) {
            return requestURL.toString();
        } else {
            return requestURL.append('?').append(queryString).toString();
        }
    }
}

Here is the TenantDBContextHolder class

public class TenantDBContextHolder {

    private static final ThreadLocal<String> TENANT_DB_CONTEXT_HOLDER = new ThreadLocal<>();

    public static void setCurrentDb(String dbType) {
        TENANT_DB_CONTEXT_HOLDER.set(dbType);
    }

    public static String getCurrentDb() {
        return TENANT_DB_CONTEXT_HOLDER.get();
    }

    public static void clear() {
        TENANT_DB_CONTEXT_HOLDER.remove();
    }
}

Now as there is already configuration for master and tenant database. In these configurations we also check for the TenantDBContextHolder class that it contains the value or not. Because when request comes for token then we check the request and set it in TenantDBContextHolder. So base on this thread local variable right database is connected and the token issue to the right database. Then in the token customizer. You can use something like the following

public class UsernamePasswordAuthenticationTokenJwtCustomizerHandler extends AbstractJwtCustomizerHandler {

    ....
    @Override
    protected void customizeJwt(JwtEncodingContext jwtEncodingContext) {
        ....
        String tenantDatabaseName = TenantDBContextHolder.getCurrentDb();
        if (StringUtils.hasText(tenantDatabaseName)) {
            URL issuerURL = jwtClaimSetBuilder.build().getIssuer();
            String issuer = issuerURL + "/" + tenantDatabaseName;
            jwtClaimSetBuilder.claim(JwtClaimNames.ISS, issuer);
        }
    
        jwtClaimSetBuilder.claims(claims ->
            userAttributes.entrySet().stream()
            .forEach(entry -> claims.put(entry.getKey(), entry.getValue()))
        );
    }
}

Now I am assuming that the Resource Server is also configure for multitenancy. Here is the link Spring Security Resource Server Multitenancy. Basically You have to configure two beans for multitenancy like the following

public class OAuth2ResourceServerConfiguration {
    ....
    @Bean
    public JWTProcessor<SecurityContext> jwtProcessor(JWTClaimsSetAwareJWSKeySelector<SecurityContext> keySelector) {
        ConfigurableJWTProcessor<SecurityContext> jwtProcessor = new DefaultJWTProcessor<>();
        jwtProcessor.setJWTClaimsSetAwareJWSKeySelector(keySelector);
        return jwtProcessor;
    }

    @Bean
    public JwtDecoder jwtDecoder(JWTProcessor<SecurityContext> jwtProcessor, OAuth2TokenValidator<Jwt> jwtValidator) {
        NimbusJwtDecoder decoder = new NimbusJwtDecoder(jwtProcessor);
        OAuth2TokenValidator<Jwt> validator = new DelegatingOAuth2TokenValidator<>(JwtValidators.createDefault(), jwtValidator);
        decoder.setJwtValidator(validator);
        return decoder;
    }
}

Now two classes for spring. From which you can get the tenant Identifier from your token.

@Component
public class TenantJwtIssuerValidator implements OAuth2TokenValidator<Jwt> {

    private final TenantDataSourceRepository tenantDataSourceRepository;
    private final Map<String, JwtIssuerValidator> validators = new ConcurrentHashMap<>();
    ....
    @Override
    public OAuth2TokenValidatorResult validate(Jwt token) {
        String issuerURL = toTenant(token);
        JwtIssuerValidator jwtIssuerValidator = validators.computeIfAbsent(issuerURL, this::fromTenant);
        OAuth2TokenValidatorResult oauth2TokenValidatorResult = jwtIssuerValidator.validate(token);
    
        String tenantDatabaseName = JwtService.getTenantDatabaseName(token);
        TenantDBContextHolder.setCurrentDb(tenantDatabaseName);
    
        return oauth2TokenValidatorResult;
    }

    private String toTenant(Jwt jwt) {
        return jwt.getIssuer().toString();
    }

    private JwtIssuerValidator fromTenant(String tenant) {
        String issuerURL = tenant;
        String tenantDatabaseName = JwtService.getTenantDatabaseName(issuerURL);
    
        TenantDataSource tenantDataSource = tenantDataSourceRepository.findByDatabaseName(tenantDatabaseName);
        if (tenantDataSource == null) {
            throw new IllegalArgumentException("unknown tenant");
        }
    
        JwtIssuerValidator jwtIssuerValidator = new JwtIssuerValidator(issuerURL);
        return jwtIssuerValidator;
    }
}

Similarly

@Component
public class TenantJWSKeySelector implements JWTClaimsSetAwareJWSKeySelector<SecurityContext> {
    ....
    @Override
    public List<? extends Key> selectKeys(JWSHeader jwsHeader, JWTClaimsSet jwtClaimsSet, SecurityContext securityContext) throws KeySourceException {
        String tenant = toTenantDatabaseName(jwtClaimsSet);
    
        JWSKeySelector<SecurityContext> jwtKeySelector = selectors.computeIfAbsent(tenant, this::fromTenant);
        List<? extends Key> jwsKeys = jwtKeySelector.selectJWSKeys(jwsHeader, securityContext);
        return jwsKeys;
    }

    private String toTenantDatabaseName(JWTClaimsSet claimSet) {
    
        String issuerURL = (String) claimSet.getClaim("iss");
        String tenantDatabaseName = JwtService.getTenantDatabaseName(issuerURL);
    
        return tenantDatabaseName;
    }

    private JWSKeySelector<SecurityContext> fromTenant(String tenant) {
        TenantDataSource tenantDataSource = tenantDataSourceRepository.findByDatabaseName(tenant);
        if (tenantDataSource == null) {
            throw new IllegalArgumentException("unknown tenant");
        } 
    
        JWSKeySelector<SecurityContext> jwtKeySelector = fromUri(jwkSetUri);
        return jwtKeySelector;
    }

    private JWSKeySelector<SecurityContext> fromUri(String uri) {
        try {
            return JWSAlgorithmFamilyJWSKeySelector.fromJWKSetURL(new URL(uri)); 
        } catch (Exception ex) {
            throw new IllegalArgumentException(ex);
        }
    }
}

Now what about authorization code grant type grant type flow. I get the tenant identifier in this case too. But when it redirects me to login page then I lost the tenant identifier because I think it creates a new request for the login page from the authorization code request. Anyways I am not sure about it because I have to look into the code of authorization code flow that what it is actually doing. So my tenant identifier is losing when it redirects me to login page.

But in case of password grant type and client credentials grant type there is no redirection so I get the tenant identifier in later stages and I can successfully use it to put into my token claims.

Then on the resource server I get the issuer url. Get the tenant identifier from the issuer url. Verify it. And it connects to the tenant database on resource server.

How I tested it. I used the spring client. You can customize the request for authorization code flow. Password and client credentials to include the custom parameters.

Thanks.

------------------ Solve the Authorization Code login problem for multitenancy -------------

I solved this issue too. Actually what I did in my security configuration. I used the following configuration

public class SecurityConfiguration {

    .....

    @Bean(name = "authenticationManager")
    public AuthenticationManager authenticationManager(AuthenticationManagerBuilder builder) throws Exception {
        AuthenticationManager authenticationManager = builder.getObject();
        return authenticationManager;
    }        

    @Bean
    @DependsOn(value = {"authenticationManager"})
    public TenantUsernamePasswordAuthenticationFilter tenantAuthenticationFilter(AuthenticationManagerBuilder builder) throws Exception {
        TenantUsernamePasswordAuthenticationFilter filter = new TenantUsernamePasswordAuthenticationFilter(); 
    
filter.setAuthenticationManager(authenticationManager(builder));
        filter.setAuthenticationDetailsSource(new TenantWebAuthenticationDetailsSource());
        //filter.setAuthenticationFailureHandler(failureHandler());
        return filter;
    }

    @Bean
    public SecurityFilterChain defaultSecurityFilterChain(HttpSecurity http) throws Exception {
        FederatedIdentityConfigurer federatedIdentityConfigurer = new FederatedIdentityConfigurer().oauth2UserHandler(new UserRepositoryOAuth2UserHandler());
    
        AuthenticationManagerBuilder authenticationManagerBuilder = http.getSharedObject(AuthenticationManagerBuilder.class); 
http.addFilterBefore(tenantAuthenticationFilter(authenticationManagerBuilder), UsernamePasswordAuthenticationFilter.class)
            .authorizeRequests(authorizeRequests -> authorizeRequests.requestMatchers(new AntPathRequestMatcher("/h2-console/**")).permitAll()
            .antMatchers("/resources/**", "/static/**", "/webjars/**").permitAll()
            .antMatchers("/login").permitAll()
            .anyRequest().authenticated()
        )
        ......
        .apply(federatedIdentityConfigurer);

        return http.build();
    }

Actually the problem was in case of Authorization Code is that you first redirect to login page. After successfully login you see the consent page. But when you comes to consent page then you lost the tenant parameter.

The reason is the spring internal class OAuth2AuthorizationEndpointFilter intercepts the request for Authorization Code. It checks user is authenticated or not. If user is not authenticated then it shows the login page. After successfully login it checks if consent is required. And if required then it makes a redirect uri with just three parameters. Here is the spring internal code

private void sendAuthorizationConsent(HttpServletRequest request, HttpServletResponse response,
        OAuth2AuthorizationCodeRequestAuthenticationToken authorizationCodeRequestAuthentication,
        OAuth2AuthorizationConsentAuthenticationToken authorizationConsentAuthentication) throws IOException {

    ....
    if (hasConsentUri()) {
        String redirectUri = UriComponentsBuilder.fromUriString(resolveConsentUri(request))
                .queryParam(OAuth2ParameterNames.SCOPE, String.join(" ", requestedScopes))
                .queryParam(OAuth2ParameterNames.CLIENT_ID, clientId)
                .queryParam(OAuth2ParameterNames.STATE, state)
                .toUriString();
        this.redirectStrategy.sendRedirect(request, response, redirectUri);
    } else {
        if (this.logger.isTraceEnabled()) {
            this.logger.trace("Displaying generated consent screen");
        }
        DefaultConsentPage.displayConsent(request, response, clientId, principal, requestedScopes, authorizedScopes, state);
    }
}

See the above method is private and I found no way that I can customize it. May be there is but I didn't find it. Anyways now your consent controller is call. But there is no tenant Identifier. You can't get it. And after consent there is no way that it connects to tenant database base in identifier.

So the first step is to add tenant identifier to login page. And then after login you should have this tenant identifier so you can set it on your consent page. And after that when you submit your consent form then this parameter will be there.

Btw I did it some time ago and may be I miss something but this is what I did.

Now how you get your parameter at login page. I solved it using the following. First I created a constant as I have to access the name from multiple times

public interface Constant {
    String TENANT_DATABASE_NAME = "tenantDatabaseName";
}

Create the following class

public class RedirectModel {

    @NotBlank
    private String tenantDatabaseName;

    public void setTenantDatabaseName(String tenantDatabaseName) {
        this.tenantDatabaseName = tenantDatabaseName;
    }

    public String getTenantDatabaseName() {
        return tenantDatabaseName;
    }
}

Then on my Login controller I get it using the following code

@Controller
public class LoginController {
    @GetMapping("/login")
    public String login(@Valid @ModelAttribute RedirectModel redirectModel,  Model model, BindingResult result) {
        if (!result.hasErrors()) {
            String tenantDatabaseName = redirectModel.getTenantDatabaseName();
            String currentDb = TenantDBContextHolder.getCurrentDb();
            LOGGER.info("Current database is {}", currentDb);
            LOGGER.info("Putting {} as tenant database name in model. So it can be set as a hidden form element ", tenantDatabaseName);
            model.addAttribute(Constant.TENANT_DATABASE_NAME, tenantDatabaseName);
        }
        return "login";
    }
}

So this is the first step that I have my tenant identifier in my login page that is send to me by request.

Now the configuration that I used in my Security configuration. You can see that I am using TenantUsernamePasswordAuthenticationFilter. Here is the filer

public class TenantUsernamePasswordAuthenticationFilter extends UsernamePasswordAuthenticationFilter {

    private static final Logger LOGGER = LogManager.getLogger();

    @Override
    public Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response)
        throws AuthenticationException {

        String tenantDatabaseName = obtainTenantDatabaseName(request);
        LOGGER.info("tenantDatabaseName is {}", tenantDatabaseName);
        LOGGER.info("Setting {} as tenant database name in thread local context.", tenantDatabaseName);
        TenantDBContextHolder.setCurrentDb(tenantDatabaseName);
        return super.attemptAuthentication(request, response);
    }

    private String obtainTenantDatabaseName(HttpServletRequest request) {
        return request.getParameter(Constant.TENANT_DATABASE_NAME);
    }
}

And in the configuration I am setting TenantWebAuthenticationDetailsSource on this filter which is here

public class TenantWebAuthenticationDetailsSource extends WebAuthenticationDetailsSource {

    @Override
    public TenantWebAuthenicationDetails buildDetails(HttpServletRequest context) {
        return new TenantWebAuthenicationDetails(context);
    }
}

Here is the class

public class TenantWebAuthenicationDetails extends WebAuthenticationDetails {

    private static final long serialVersionUID = 1L;

    private String tenantDatabaseName; 

    public TenantWebAuthenicationDetails(HttpServletRequest request) {
        super(request);
        this.tenantDatabaseName = request.getParameter(Constant.TENANT_DATABASE_NAME);
}

    public TenantWebAuthenicationDetails(String remoteAddress, String sessionId, String tenantDatabaseName) {
        super(remoteAddress, sessionId);
        this.tenantDatabaseName = tenantDatabaseName;
    }

    public String getTenantDatabaseName() {
        return tenantDatabaseName;
    }
}

Now after spring authenticates the user then I have the tenant name in details. Then in the consent controller I use

@Controller
public class AuthorizationConsentController {
    ....
    @GetMapping(value = "/oauth2/consent")
    public String consent(Authentication authentication, Principal principal, Model model,
        @RequestParam(OAuth2ParameterNames.CLIENT_ID) String clientId,
        @RequestParam(OAuth2ParameterNames.SCOPE) String scope,
        @RequestParam(OAuth2ParameterNames.STATE) String state) {
        ......
        String registeredClientName = registeredClient.getClientName();
    Object webAuthenticationDetails = authentication.getDetails();
        if (webAuthenticationDetails instanceof TenantWebAuthenicationDetails) {
            TenantWebAuthenicationDetails tenantAuthenticationDetails = (TenantWebAuthenicationDetails)webAuthenticationDetails;
            String tenantDatabaseName = tenantAuthenticationDetails.getTenantDatabaseName();
            model.addAttribute(Constant.TENANT_DATABASE_NAME, tenantDatabaseName);
        }
    
        model.addAttribute("clientId", clientId);
        .....
        return "consent-customized";
    }
}

Now I have my tenant identifier on my consent page. After submitting it it's in the request parameter.

There is another class that I used and it was

public class TenantLoginUrlAuthenticationEntryPoint extends LoginUrlAuthenticationEntryPoint {

    public TenantLoginUrlAuthenticationEntryPoint(String loginFormUrl) {
        super(loginFormUrl);
    }

    @Override
    protected String determineUrlToUseForThisRequest(HttpServletRequest request, HttpServletResponse response,
        AuthenticationException exception) {

        String tenantDatabaseNameParamValue = request.getParameter(Constant.TENANT_DATABASE_NAME);
        String redirect = super.determineUrlToUseForThisRequest(request, response, exception);
        String url = UriComponentsBuilder.fromPath(redirect).queryParam(Constant.TENANT_DATABASE_NAME, tenantDatabaseNameParamValue).toUriString();
        return url;
    }
}

Anyways this is how I solved it. I don't have any such requirement in any of my project but I want to do it using this new server so I just solved it in this way.

Anyways there is lot of code. I tested it using the Spring oauth2 client and it was working. Hopefully I will create some project and upload it on my Github. Once I will run it again then I will put more explanation here of the flow. Specially for the last part that after submitting the consent how it set in the Thread Local variable.

After that everything is straight forward.

Hopefully it will help.

Thanks