I have a small problem at hand, which revolves around learning Angular with Spring-enabled REST endpoints that use a DB to store data and have a security layer in between that should interact with an LDAP for authentication and authorization, and, finally, the application should run as one smooth unit. It will be too much to cover in a single post so I will be writing multiple blogs in continuation to this one.

There were multiple points where I could have started, but, in retrospect, as I blog about it, the best starting point is to think about the services alone at first, what you want to develop, and create them independently and test them as a unit before you can proceed to any other component.

The other way could have been to define the functional signature and agree on an expectation, especially if it was a project with more than one team member and it would have been much easier to develop in parallel.

Anyway, I am just using my spare time to develop it, so I thought of crunching some sample code to try out the service that I wanted before jumping into the actual application.

The starting point, as always, is Spring initializer, and it helped me chose what I wanted and get the guidelines of the project to start with.

<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-ldap</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-rest</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-security</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.security</groupId>
<artifactId>spring-security-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>

Since I have added these dependencies, and am using IntelliJ to develop, life becomes a little easier.

The current code looks minimal with just two classes:

@SpringBootApplication
public class EventsServicesApplication {
public static void main(String[] args) {
SpringApplication.run(EventsServicesApplication.class, args);
}
}

And

public class ServletInitializer extends SpringBootServletInitializer {
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
return application.sources(EventsServicesApplication.class);
}
}

So, the scaffolding is ready, and it is time to add some dummy capabilities to try out.

You can configure a few properties in the application.properties file:

spring.profiles.active=default
server.port=8082
server.servlet.context-path=/events
logging.level.org.springframework=DEBUG

If you execute this, watch out for the information in the console that can help you understand what is getting initialized and how the Spring Framework is helping to stitch the capability that we are trying to achieve.

2019-04-23 23:15:10.932  INFO 62835 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8082 (http) with context path '/events'
2019-04-23 23:15:10.938  INFO 62835 --- [           main] m.s.E.EventsServicesApplication          : Started EventsServicesApplication in 3.486 seconds (JVM running for 4.881)

I added my first controller and made it a RestController:

@RestController
public class ControllerOne {

    @GetMapping("/")
    @ResponseBody
    public String bonsoir(@RequestParam(name = "id", required = false) String id, HttpServletRequest request) {
        if(id != null )
        return "Bonsoir " + id + " !";
        else
            return "Bonsoir!";
    }

    @ResponseBody
    @GetMapping("/error")
    public String errorMessage(HttpServletRequest request) {
        return "Error occurred, please see the server logs.";
    }
}

At this moment, if you try to call the endpoint using any of the REST clients (your preference, but I use Insomnia) in this application, you may see something like this:

> GET /events HTTP/1.1
> Host: localhost:8082
> User-Agent: insomnia/6.3.2
> Cookie: JSESSIONID=67570EB8C6F2A822F908C4A9F1CBA2E7
> Accept: */*

The response would be:

< HTTP/1.1 401 
< Set-Cookie: JSESSIONID=DBC2F7DF3DBE01D6E3B45E9B311ABB66; Path=/events; HttpOnly
< WWW-Authenticate: Basic realm="Realm"
< X-Content-Type-Options: nosniff
< X-XSS-Protection: 1; mode=block
< Cache-Control: no-cache, no-store, max-age=0, must-revalidate
< Pragma: no-cache
< Expires: 0
< X-Frame-Options: DENY
< Content-Type: application/json;charset=UTF-8
< Transfer-Encoding: chunked
< Date: Tue, 23 Apr 2019 17:47:07 GMT

It is simply because we have enabled the security, which enforces all the request that is being sent to this server are being scrutinized and by default, the value that it uses for the WebSecurityConfigurerAdapter is below

http.authorizeRequests().anyRequest().authenticated().and().formLogin().and().httpBasic();

All requests that reach the server are all evaluated for the right Access.

org.springframework.security.access.AccessDeniedException: Access is denied
at org.springframework.security.access.vote.AffirmativeBased.decide(AffirmativeBased.java:84) ~[spring-security-core-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.access.intercept.AbstractSecurityInterceptor.beforeInvocation(AbstractSecurityInterceptor.java:233) ~[spring-security-core-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:124) ~[spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:91) ~[spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:119) ~[spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:137) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:170) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilterInternal(BasicAuthenticationFilter.java:158) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.authentication.ui.DefaultLogoutPageGeneratingFilter.doFilterInternal(DefaultLogoutPageGeneratingFilter.java:52) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.authentication.ui.DefaultLoginPageGeneratingFilter.doFilter(DefaultLoginPageGeneratingFilter.java:206) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:200) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:100) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:74) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:215) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:178) [spring-security-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:357) [spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:270) [spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) [spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:92) [spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) [spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) [spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.1.6.RELEASE.jar:5.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:200) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1415) [tomcat-embed-core-9.0.17.jar:9.0.17]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.17.jar:9.0.17]
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167) [na:na]
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641) [na:na]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.17.jar:9.0.17]
at java.base/java.lang.Thread.run(Thread.java:844) [na:na]

Now, it's time to customize security.

I started by adding extending the WebSecurityConfigurerAdapter:

@Configuration
@EnableWebSecurity(debug = true)
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests().anyRequest().permitAll();
    }
}

What I have done in the configure method is bypassed all the security explicitly by stating that permits all the requests with the overridden configure method.

Spring Data LDAP

Now, it's time to start with the LDAP structuring. From the introduction available at spring.io:

The Spring Data LDAP project provides repository abstractions for Spring LDAP 
on top of Spring LDAP’s LdapTemplate and Object-Directory Mapping.

Object-relational mapping frameworks like Hibernate and JPA offers developers the ability to use annotations to map relational database tables to Java objects. Spring LDAP project offers a similar ability with respect to LDAP directories through a number of methods: in LdapOperations

Also, note:

Spring LDAP repositories can be enabled by using a <data-ldap:repositories> 
tag in your XML configuration or by using an @EnableLdapRepositories annotation 
on a configuration class.

For LDAP source, I am using ApacheDS, which is fairly easy to use and manage.

With typical user attributes under:

Points to remember straight from the documentation:

1. All Spring LDAP repositories must work with entities annotated with the ODM annotations, as described in Object-Directory Mapping.
2. Since all ODM managed classes must have a Distinguished Name as the ID, all Spring LDAP repositories must have the ID type parameter set to javax.naming.Name. Indeed, the built-in LdapRepository only takes one type parameter: the managed entity class, which defaults the ID to javax.naming.Name.
3. Due to specifics of the LDAP protocol, paging and sorting are not supported for Spring LDAP repositories.

I wanted to try out user listing first, so the first thing I need to define is the ODM for the user.

1. Add the Maven dependency:

<dependency>
        <groupId>org.springframework.ldap</groupId>
        <artifactId>spring-ldap-core</artifactId>
</dependency>
 <dependency>
    <groupId>org.springframework.data</groupId>
<artifactId>spring-data-ldap</artifactId>
</dependency>

Add the Entity class with the right annotation:

@Entry(base="ou=users", objectClasses = {
        "top",
        "inetOrgPerson", "person", "organizationalPerson",
        "simpleSecurityObject"})
public class UserModel {

    @JsonIgnore
    @Id
    private Name id;

    @JsonProperty("userName")
    private @Attribute(name = "uid") String uid;

    @JsonProperty("firstName")
    private @Attribute(name = "cn") String firstName;


    @JsonIgnore
    private @Attribute(name = "displayname") String displayName;

    @JsonProperty("lastName")
    private  @Attribute(name = "sn") String lastName;



    public UserModel(String uid, String firstName, String displayName, String lastName) {
        this.uid = uid;
        this.firstName = firstName;
        this.displayName = displayName;
        this.lastName = lastName;
    }

    public UserModel(String userName, String firstName, String lastName) {
        this.uid = userName;
        this.firstName = firstName;
        this.lastName = lastName;
    }

    public UserModel() {

    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getUid() {
        return uid;
    }



    public void setUid(String uid) {
        this.uid = uid;
    }

    public String getDisplayName() {
        return displayName;
    }

    public void setDisplayName(String displayName) {
        this.displayName = displayName;
    }

    @Override
    public String toString() {
        return "UserModel{" +
                "uid='" + uid + '\'' +
                ", firstName='" + firstName + '\'' +
                ", displayName='" + displayName + '\'' +
                ", lastName='" + lastName + '\'' +
                '}';
    }
}

Add configuration:

@Configuration
@EnableLdapRepositories(basePackages = "me.samarthya.EventsServices.ldap")
public class ApacheDSConfiguration {
    @Bean
    LdapTemplate ldapTemplate(ContextSource contextSource) {
        return new LdapTemplate(contextSource);
    }
}

Add properties:

spring.ldap.base=dc=example,dc=com
spring.ldap.password=secret
spring.ldap.username=uid=admin,ou=system
spring.ldap.urls=ldap://localhost:10389

Create repository:

@Repository
public interface ApacheDSRepository extends LdapRepository<UserModel> {

}

Added a method in the controller to get the user list:

 @ResponseBody
    @GetMapping("/users")
    public Iterable<UserModel> getAllUsers() {
        return apacheDSRepository.findAll();
    }

Fire away any request to find the information:

> GET /events/users HTTP/1.1
> Host: localhost:8082
> User-Agent: insomnia/6.3.2
> Cookie: JSESSIONID=438BF9E64596D6A1F96F49E7302BB8A9; JSESSIONID=67570EB8C6F2A822F908C4A9F1CBA2E7
> Accept: */*


< HTTP/1.1 200 
< X-Content-Type-Options: nosniff
< X-XSS-Protection: 1; mode=block
< Cache-Control: no-cache, no-store, max-age=0, must-revalidate
< Pragma: no-cache
< Expires: 0
< X-Frame-Options: DENY
< Content-Type: application/json;charset=UTF-8
< Transfer-Encoding: chunked
< Date: Wed, 24 Apr 2019 09:02:06 GMT

If you wish to see the code, it is available on GitHub.