How to set active spring 3.1 environment profile via a properites file and not via an env variable or system property

We use the new environment profiles feature of spring 3.1. We currently set the active profile by setting the environment variable spring.profiles.active=xxxxx on the server to which we deploy the application.

We think this is a suboptimal solution as the war file we want to deploy should just have an additional properties file which sets the environment in which the spring app context should load so the deployment is not dependent on some env var set on the server.

I tried to figure out how to do that and found:

ConfigurableEnvironment.setActiveProfiles()

which I can use to programmatically set the profile but then I still don't know where and when to execute this code. Somewhere where the spring context loads up? Can I load the parameter I want to pass to the method from a properties file?

UPDATE: I just found at docs which I might be able to implement to set the active profile?

In web.xml

<context-param>
    <param-name>spring.profiles.active</param-name>
    <param-value>profileName</param-value>
</context-param>

Using WebApplicationInitializer

This approach is used when you don't have a web.xml file in Servlet 3.0 environment and are bootstrapping the Spring completely from Java:

class SpringInitializer extends WebApplicationInitializer {

    void onStartup(ServletContext container) {
        AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext();
        rootContext.getEnvironment().setActiveProfiles("profileName");
        rootContext.register(SpringConfiguration.class);
        container.addListener(new ContextLoaderListener(rootContext));
    }
}

Where SpringConfiguration class is annotated with @Configuration.

The answer from Thomasz is valid as long as the profile name can be provided statically in the web.xml or one uses the new XML-less configuration type where one could programmatically load the profile to set from a properties file.

As we still use the XML version I investigated further and found the following nice solution where you implement your own ApplicationContextInitializer where you just add a new PropertySource with a properties file to the list of sources to search for environment specific configuration settings. in the example below one could set the spring.profiles.active property in the env.properties file.

public class P13nApplicationContextInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {

    private static Logger LOG = LoggerFactory.getLogger(P13nApplicationContextInitializer.class);

    @Override
    public void initialize(ConfigurableApplicationContext applicationContext) {
        ConfigurableEnvironment environment = applicationContext.getEnvironment();
        try {
            environment.getPropertySources().addFirst(new ResourcePropertySource("classpath:env.properties"));
            LOG.info("env.properties loaded");
        } catch (IOException e) {
            // it's ok if the file is not there. we will just log that info.
            LOG.info("didn't find env.properties in classpath so not loading it in the AppContextInitialized");
        }
    }

}

You then need to add that initializer as a parameter to the ContextLoaderListener of spring as follows to your web.xml:

<context-param>
    <param-name>contextInitializerClasses</param-name>
    <param-value>somepackage.P13nApplicationContextInitializer</param-value>
</context-param>
<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

You can also apply it to DispatcherServlet:

<servlet>
    <servlet-name>dispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextInitializerClasses</param-name>
        <param-value>somepackage.P13nApplicationContextInitializer</param-value>
    </init-param>
</servlet>

For some reason only one way works for me

public class ActiveProfileConfiguration implements ServletContextListener {   
    @Override
    public void contextInitialized(ServletContextEvent sce) {
        System.setProperty(AbstractEnvironment.DEFAULT_PROFILES_PROPERTY_NAME, "dev");
        System.setProperty(AbstractEnvironment.ACTIVE_PROFILES_PROPERTY_NAME, "dev");
    }

....

 <listener>
     <listener-class>somepackahe.ActiveProfileConfiguration</listener-class>
 </listener>
 <listener>
     <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
 </listener>