1. Overview
This article will explain how to setup Spring Security with Maven and will go over specific usecases of using Spring Security dependencies. The latest Spring Security releases can be found on Maven Central [3].
This is a followup to the previous Spring with Maven article [4], so for non-security Spring dependencies, that’s the place to start.
2. Spring Security with Maven
2.1. spring-security-core
The Core Spring Security support – spring-security-core – contains authentication and access control functionality, and has support for standalone (non-web) applications, method level security and JDBC:
<properties>
<org.springframework.security.version>3.1.3.RELEASE</org.springframework.security.version>
<org.springframework.version>3.2.2.RELEASE</org.springframework.version>
</properties>
<dependency>
<groupId>org.springframework.security</groupId>
<artifactId>spring-security-core</artifactId>
<version>${org.springframework.security.version}</version>
</dependency>
Notice that we’re using the 3.1.3.RELEASE version of Spring Security – Spring and Spring Security are on different release schedules, so there isn’t a 1:1 match between the version numbers.
Also very important to understand is the fact that, unintuitively, Spring Security 3.1.x do not depend on Spring 3.1.x releases – this is because Spring Security 3.1.x was released before Spring 3.1. The plan is to align these dependencies more closely in future releases – see this JIRA [5] for more details – but for the time being, this has practical implications that we will look at next.
2.2. spring-security-web
To add Web support for Spring Security, the spring-security-web dependency is required:
<dependency>
<groupId>org.springframework.security</groupId>
<artifactId>spring-security-web</artifactId>
<version>${org.springframework.security.version}</version>
</dependency>
This contains filters and related web security infrastructure enabling URL access control in a servlet environment.
This new dependency also exhibits a problem for the Maven dependency graph – as mentioned above, Spring Security may depend on 3.0.x Spring dependencies – which may lead to these older dependencies making their way on top the classpath instead of the newer 3.2.x Spring artifacts.
To understand why this is happening, we need to look at how Maven resolves conficts – in case of a version confict, Maven will pick the jar that is closest to the root of the tree. In our case, spring-jdbc is defined by both spring-orm (with the 3.2.2.RELEASE version) but also by spring-security-web (with the 3.0.7.RELEASE version) – so in both cases, spring-jdbc is defined at a depth of 1 from the root pom of our project. Because of that, it will actually matter in which order spring-orm and spring-security-web are defined in our own pom – the first one will take priority so we may end up with either version on our classpath.
To address this problem, we will have to explicitly define some of the Spring dependencies in our own pom and not rely on the implicit Maven dependency resolution mechanism – doing this will put that particular dependency at depth 0 from our pom (as it’s defined in the pom itslef) so it will take priority. All of the following fall into the same category and all need to be explicitly defined, either directly or, for multi-module projects, in the dependencyManagement element of the parent:
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-expression</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
</dependency>
2.3. spring-security-config and others
To use the rich Spring Security XML namespace, the spring-security-config dependency will be required:
<dependency>
<groupId>org.springframework.security</groupId>
<artifactId>spring-security-config</artifactId>
<version>${org.springframework.security.version}</version>
<scope>runtime</scope>
</dependency>
No application code should compile against this dependency, so it should be scoped as runtime.
Finally, LDAP, ACL, CAS and OpenID support have their own dependencies in Spring Security: spring-security-ldap, spring-security-acl, spring-security-cas and spring-security-openid.
3. Using Snapshots and Milestones
Spring Security milestones [6] as well as snapshots [7] are available in the custom Maven repositories provided by Spring – for additional details about how to configure these, see how to use Snapshots and Milestones [8].
4. Conclusion
This article discusses the practical details of using Spring Security with Maven. The Maven dependencies presented here are of course some of the major ones, and there are several others that may be worth mentioning and have not yet made the cut. Nevertheless this should be a good starting point for using Spring in a Maven enabled project.
P.S. You might dig following me on Twitter [9].