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

I found a solution for using spring-cloud-zookeeper without Spring Boot, based on the idea provided here https://wenku.baidu.com/view/493cf9eba300a6c30d229f49.html

It should be easily updated to match your needs and using a Spring Cloud Config Server (the CloudEnvironement class needs to be updated to load the file from the server instead of Zookeeper)

First, create a CloudEnvironement class that will create a PropertySource (ex from Zookeeper) :

CloudEnvironement.java

  public class CloudEnvironment extends StandardServletEnvironment { 

  @Override 
  protected void customizePropertySources(MutablePropertySources propertySources) { 
    super.customizePropertySources(propertySources); 
    try { 
      propertySources.addLast(initConfigServicePropertySourceLocator(this)); 
    } 
    catch (Exception ex) { 
      logger.warn("failed to initialize cloud config environment", ex); 
    } 
  } 

  private PropertySource initConfigServicePropertySourceLocator(Environment environment) { 
    ZookeeperConfigProperties configProp = new ZookeeperConfigProperties(); 
    ZookeeperProperties props = new ZookeeperProperties(); 
    props.setConnectString("myzookeeper:2181"); 
    CuratorFramework fwk = curatorFramework(exponentialBackoffRetry(props), props); 
    ZookeeperPropertySourceLocator propertySourceLocator = new ZookeeperPropertySourceLocator(fwk, configProp); 
    PropertySource source= propertySourceLocator.locate(environment); 
    return source ; 
  } 

  private CuratorFramework curatorFramework(RetryPolicy retryPolicy, ZookeeperProperties properties) { 
    CuratorFrameworkFactory.Builder builder = CuratorFrameworkFactory.builder(); 
    builder.connectString(properties.getConnectString()); 
    CuratorFramework curator = builder.retryPolicy(retryPolicy).build(); 
    curator.start(); 
    try { 
      curator.blockUntilConnected(properties.getBlockUntilConnectedWait(), properties.getBlockUntilConnectedUnit()); 
    } 
    catch (InterruptedException e) { 
      throw new RuntimeException(e); 
    } 
    return curator; 
  } 

  private RetryPolicy exponentialBackoffRetry(ZookeeperProperties properties) { 
    return new ExponentialBackoffRetry(properties.getBaseSleepTimeMs(), 
        properties.getMaxRetries(), 
        properties.getMaxSleepMs()); 
  } 

}

Then create a custom XmlWebApplicationContext class : it will enable to load the PropertySource from Zookeeper when your webapplication start and replace the bootstrap magic of Spring Boot:

MyConfigurableWebApplicationContext.java

public class MyConfigurableWebApplicationContext extends XmlWebApplicationContext { 

  @Override 
  protected ConfigurableEnvironment createEnvironment() { 
    return new CloudEnvironment(); 
  } 
}

Last, in your web.xml file add the following context-param for using your MyConfigurableWebApplicationContext class and bootstraping your CloudEnvironement.

           
      contextClass 
      com.kiabi.config.MyConfigurableWebApplicationContext 
     

If you use a standard property file configurer, it should still be loaded so you can have properties in both a local file and Zookeeper.

For all this to work you need to have spring-cloud-starter-zookeeper-config and curator-framework jar in your classpath with their dependancy, if you use maven you can add the following to your pom.xml

        
            
                org.springframework.cloud
                spring-cloud-zookeeper-dependencies
                1.1.1.RELEASE
                pom
                import
            
        
    

    
        
            org.springframework.cloud
            spring-cloud-starter-zookeeper-config
        
        
            org.apache.curator
            curator-framework