Intro to Spring Security LDAP

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1. Overview

In this quick tutorial, we will learn how to set up Spring Security LDAP.

Before we start, a note about what LDAP is – it stands for Lightweight Directory Access Protocol and it’s an open, vendor-neutral protocol for accessing directory services over a network.

Spring LDAP Overview

Learn how to use the Spring LDAP APIs to authenticate and search for users, as well as to create and modify users in the directory server.

Guide to Spring Data LDAP

Learn how to use Spring Data with LDAP.

Spring Data with Spring Security

See how to integrate Spring Data with Spring Security.

2. Maven Dependency

First, let take a look at maven dependencies we need:

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

<dependency>
    <groupId>org.apache.directory.server</groupId>
    <artifactId>apacheds-server-jndi</artifactId>
    <version>1.5.5</version>
</dependency>

Note: We used ApacheDS as our LDAP server which is an extensible and embeddable directory server.

3. Java Configuration

Next, let’s discuss our Spring Security Java configuration:

public class SecurityConfig {

    @Bean
    ApacheDSContainer ldapContainer() throws Exception {
        return new ApacheDSContainer("dc=baeldung,dc=com", "classpath:users.ldif");
    }

    @Bean
    LdapAuthoritiesPopulator authorities(BaseLdapPathContextSource contextSource) {
        String groupSearchBase = "ou=groups";
        DefaultLdapAuthoritiesPopulator authorities = new DefaultLdapAuthoritiesPopulator
           (contextSource, groupSearchBase);
        authorities.setGroupSearchFilter("(member={0})");
        return authorities;
    }

    @Bean
    AuthenticationManager authenticationManager(BaseLdapPathContextSource contextSource, 
        LdapAuthoritiesPopulator authorities) {
        LdapBindAuthenticationManagerFactory factory = new LdapBindAuthenticationManagerFactory
           (contextSource);
        factory.setUserSearchBase("ou=people");
        factory.setUserSearchFilter("(uid={0})");
        return factory.createAuthenticationManager();
    }
    
    // ...
 }

4. XML Configuration

Now, let’s take a look at the corresponding XML configuration:

<authentication-manager>
    <ldap-authentication-provider
      user-search-base="ou=people"
      user-search-filter="(uid={0})"
      group-search-base="ou=groups"
      group-search-filter="(member={0})">
    </ldap-authentication-provider>
</authentication-manager>
   
<ldap-server root="dc=baeldung,dc=com" ldif="users.ldif"/>

5. LDAP Data Interchange Format

LDAP data can be represented using the LDAP Data Interchange Format (LDIF) – here’s an example of our user data:

dn: ou=groups,dc=baeldung,dc=com
objectclass: top
objectclass: organizationalUnit
ou: groups

dn: ou=people,dc=baeldung,dc=com
objectclass: top
objectclass: organizationalUnit
ou: people

dn: uid=baeldung,ou=people,dc=baeldung,dc=com
objectclass: top
objectclass: person
objectclass: organizationalPerson
objectclass: inetOrgPerson
cn: Jim Beam
sn: Beam
uid: baeldung
userPassword: password

dn: cn=admin,ou=groups,dc=baeldung,dc=com
objectclass: top
objectclass: groupOfNames
cn: admin
member: uid=baeldung,ou=people,dc=baeldung,dc=com

dn: cn=user,ou=groups,dc=baeldung,dc=com
objectclass: top
objectclass: groupOfNames
cn: user
member: uid=baeldung,ou=people,dc=baeldung,dc=com

6. Using Spring Boot

When working on a Spring Boot project, we can also use Spring Boot Starter Data Ldap dependency that will automatically instrument LdapContextSource and LdapTemplate for us.

To enable autoconfiguration, we need to ensure that we have the spring-boot-starter-data-ldap Starter or spring-ldap-core defined as a dependency in our pom.xml:

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

To connect to LDAP, we need to provide the connection settings in the application.properties:

spring.ldap.url=ldap://localhost:18889
spring.ldap.base=dc=example,dc=com
spring.ldap.username=uid=admin,ou=system
spring.ldap.password=secret

More details about Spring Data LDAP autoconfiguration can be found in the official documentation. Spring Boot brings in LdapAutoConfiguration which takes care of instrumentation of LdapTemplate which can then be injected into the required service class:

@Autowired
private LdapTemplate ldapTemplate;

7. The Application

Finally, here is our simple application:

@Controller
public class MyController {

    @RequestMapping("/secure")
    public String secure(Map<String, Object> model, Principal principal) {
        model.put("title", "SECURE AREA");
        model.put("message", "Only Authorized Users Can See This Page");
        return "home";
    }
}