Spring Boot - using Externalized Configuration values in @Configuration classes

I needed to externalize our session storage, so have used spring-session.

Following their examples at http://ift.tt/1DqHK8x, I created my EmbeddedRedisConfiguration and everything works as it should.

I decided that I wanted optional support to specify the Redis executable path, in the case of pre existing local redis server, so I have added to /resources/config/application.properties the following key value redis.embedded.executable.path==/path/to/redis.

My immediate thought was then to just use @Value annotation in my configuration, and have access to the value

static class RedisServerBean implements InitializingBean, DisposableBean, BeanDefinitionRegistryPostProcessor {
    private RedisServer redisServer;

    @Value("${redis.embedded.executable.path}")
    String executablePath;

    public void afterPropertiesSet() throws Exception {
        if (executablePath != null) {
            redisServer = new RedisServer(new File(executablePath), Protocol.DEFAULT_PORT);    
        } else {
            redisServer = new RedisServer(Protocol.DEFAULT_PORT);
        }
        redisServer.start();
    }

    public void destroy() throws Exception {
        if(redisServer != null) {
            redisServer.stop();
        }
    }

    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {}

    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {}
}

However, executablePath is always null. As you know, if you use an @Value in a @Service class or equivalent, the value will be populated.

I assume that this configuration is being invoked before the beans that load the properties, but I also know this is possible, because eg @DatasourceAutoConfiguration can use spring.datasource.* properties

I am obviously overlooking something simple here. Do I require my own @ConfigurationProperties