Spring Cloud Config Client Without Spring Boot

Question

We have an existing spring web app deployed as a WAR file into Amazon Elastic Beanstalk. Currently we load properties files as http resources to give us a single source of p

Answer 1

Refrenced: https://wenku.baidu.com/view/493cf9eba300a6c30d229f49.html

Root WebApplicationContext and the Servlet WebApplicationContext uses Environment and initializes PropertySources based on the spring profile. For non-spring boot apps, we need to customize these to get the properties from Config Server and to refresh the beans whenever there is a property change. Below are the changes that needs to happen to get the config working in SpringMVC. You will also need a system property for spring.profile.active

1. Create a CustomBeanFactoryPostProcessor and set lazyInit on all bean definitions to true to initialize all bean lazily i.e. beans are initialized only upon a request.

   @Component
   public class AddRefreshScopeProcessor implements BeanFactoryPostProcessor, ApplicationContextAware {
   
   private static ApplicationContext applicationContext;
   
   @SuppressWarnings("unchecked")
   @Override
   public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
   
       String[] beanNames = applicationContext.getBeanDefinitionNames();
       for(int i=0; i T getBean(Class beanClass) {
       return applicationContext.getBean(beanClass);
   }
   
   /**
    * Get a Spring bean by name.
    * 
    * @param beanName
    * @return
    */
   public static Object getBean(String beanName) {
       return applicationContext.getBean(beanName);
     }
   }
   

2. Create a custom class extending StandardServletEnvironment and overriding the initPropertySources method to load additional PropertySources (from config server).

    public class CloudEnvironment extends StandardServletEnvironment {
   
     @Override
       public void initPropertySources(ServletContext servletContext, ServletConfig servletConfig) {
    super.initPropertySources(servletContext,servletConfig);
    customizePropertySources(this.getPropertySources());
      }
   
   @Override
     protected void customizePropertySources(MutablePropertySources propertySources) {
       super.customizePropertySources(propertySources);
       try {
         PropertySource source = initConfigServicePropertySourceLocator(this);
         propertySources.addLast(source);
   
       } catch (
   
       Exception ex) {
         ex.printStackTrace();
       }
     }
   
     private PropertySource initConfigServicePropertySourceLocator(Environment environment) {
   
       ConfigClientProperties configClientProperties = new ConfigClientProperties(environment);
       configClientProperties.setUri("http://localhost:8888");
       configClientProperties.setProfile("dev");
       configClientProperties.setLabel("master");
       configClientProperties.setName("YourApplicationName");
   
       System.out.println("##################### will load the client configuration");
       System.out.println(configClientProperties);
   
       ConfigServicePropertySourceLocator configServicePropertySourceLocator =
           new ConfigServicePropertySourceLocator(configClientProperties);
   
       return configServicePropertySourceLocator.locate(environment);
       }
   
     }
   

3. Create a custom ApplicatonContextInitializer and override the initialize method to set the custom Enviroment instead of the StandardServletEnvironment.

   public class ConfigAppContextInitializer implements ApplicationContextInitializer {
   
   @Override
   public void initialize(ConfigurableApplicationContext applicationContext) {
       applicationContext.setEnvironment(new CloudEnvironment());
     }
   }
   

4. Modify web.xml to use this custom context initializer for both application context and servlet context.

   
       dispatcher
           
               org.springframework.web.servlet.DispatcherServlet
           
       
           contextInitializerClasses
           com.my.context.ConfigAppContextInitializer
       
       1
   
   
   
   
       dispatcher
       /
   
   
   
    org.springframework.web.context.ContextLoaderListener
   
   
   
       contextInitializerClasses
       com.my.context.ConfigAppContextInitializer
   
   
   
       contextConfigLocation
       /WEB-INF/dispatcher-servlet.xml
   
   

5. To refresh the beans created a refresh endpoint you will also need to refresh the application Context.

   @Controller
   public class RefreshController {
   
   @Autowired
   private RefreshAppplicationContext refreshAppplicationContext;
   
   @Autowired
   private RefreshScope refreshScope;
   
   @RequestMapping(path = "/refreshall", method = RequestMethod.GET)
   public String refresh() {
       refreshScope.refreshAll();
       refreshAppplicationContext.refreshctx();
       return "Refreshed";
   }
   }
   

RefreshAppplicationContext.java

@Component
public class RefreshAppplicationContext implements ApplicationContextAware {

    private ApplicationContext applicationContext;
    public void setApplicationContext(ApplicationContext applicationContext) {
        this.applicationContext = applicationContext;
    }


    public void refreshctx(){
        ((XmlWebApplicationContext)(applicationContext)).refresh();
    }
}