ZooKeeper for Java / Spring配置？ [英] ZooKeeper for Java/Spring Config?
问题描述
有没有很好记录的Apache ZooKeeper用于分布Java应用程序的配置，特别是Spring服务的使用案例？
像许多云服务用户一样需要更改可变数量Java服务的配置，最好在运行时更改，而不需要重新启动服务。
UPDATE
最后，我写了一些东西，将一个ZooKeeper节点作为属性文件加载，并创建一个 ResourcePropertySource 将它插入到Spring上下文中。注意这不会反映在上下文开始之后ZooKeeper节点的变化。
public class ZooKeeperPropertiesApplicationContextInitializer实现ApplicationContextInitializer< ConfigurableApplicationContext> {
private static final Logger logger = LoggerFactory.getLogger（ZooKeeperPropertiesApplicationContextInitializer.class）;
private final CuratorFramework curator;
private String projectName;
private String projectVersion;
public ZooKeeperPropertiesApplicationContextInitializer（）throws IOException {
logger.trace（尝试构造CuratorFramework实例）;
RetryPolicy retryPolicy = new ExponentialBackoffRetry（10，100）;
curator = CuratorFrameworkFactory.newClient（zookeeper，retryPolicy）;
curator.start（）;
}
/ **
*向应用程序上下文中添加主属性源，从预先存在的ZooKeeper节点
*中填充。
* /
@Override
public void initialize（ConfigurableApplicationContext applicationContext）{
logger.trace（尝试向ApplicationContext PropertySources添加ZooKeeper派生的属性）;
尝试{
populateProjectProperties（）;
属性properties = populatePropertiesFromZooKeeper（）;
PropertiesPropertySource propertySource = new PropertiesPropertySource（zookeeper，properties）;
applicationContext.getEnvironment（）。getPropertySources（）。addFirst（propertySource）;
logger.debug（向ApplicationContext PropertySources添加了ZooKeeper派生的属性）;
curator.close（）;
} catch（IOException e）{
logger.error（IO错误尝试从ZooKeeper加载属性，e）;
throw new IllegalStateException（无法加载ZooKeeper配置）;
} catch（Exception e）{
logger.error（IO错误尝试从ZooKeeper加载属性，e）;
throw new IllegalStateException（无法加载ZooKeeper配置）;
} finally {
if（curator！= null& curator.isStarted（））{
curator.close（）;
}
}
}
/ **
*从属性文件填充Maven工件名称和版本，
*应该是在类路径上，通过Maven过滤输入的值。
*
*有一种方法来做这些与清单，但它是一个正确的faff当
*创建阴影uber-jar。
*
* @throws IOException
* /
private void populateProjectProperties（）throws IOException {
logger.trace（尝试从属性文件中获取项目名称和版本）;
try {
ResourcePropertySource projectProps = new ResourcePropertySource（project.properties）;
this.projectName =（String）projectProps.getProperty（project.name）;
this.projectVersion =（String）projectProps.getProperty（project.version）;
} catch（IOException e）{
logger.error（IO错误尝试找到项目名称和版本，以便从ZooKeeper获取属性）;
}
}
/ **
*实际加载属性。
*
* @return
* @throws异常
* @throws IOException
* /
private属性populatePropertiesFromZooKeeper（）throws Exception，IOException {
logger.debug（尝试从ZooKeeper获取属性）;
try {
byte [] bytes = curator.getData（）。forPath（/ distributed-config /+ projectName +/+ projectVersion）;
InputStream in = new ByteArrayInputStream（bytes）;
属性properties = new属性（）;
property.load（in）;
return property; $ {$} $ {$} $ {$} $ {$} $ {$} $ {$} $ {$} $ {
} {
} {
logger.error（无法从ZooKeeper加载应用程序配置项目[{}]：[{}]，projectName，projectVersion）
throw e;
}
}
}
我上周在James Strachen的Apache Camel演讲中提到，他们使用ZooKeeper作为云中的基于Java的服务器作为配置信息的来源。
我见过Adrian Colyer ）在我看来，如果你从一个典型的架构的Spring应用程序开始，我不会看不到你有一个简单的工作改造动态配置更改的顶部。
Are there any well documented use cases of Apache ZooKeeper being used to distribute configuration of Java applications, and in particular Spring services?
Like many users of cloud services I have a requirement to change the configuration of a variable amount of Java services, preferably at run-time without needing to restart the services.
UPDATE
Eventually I ended up writing something that would load a ZooKeeper node as a properties file, and create a ResourcePropertySource and insert it into a Spring context. Note that this will not reflect changes in the ZooKeeper node after the context has started.
public class ZooKeeperPropertiesApplicationContextInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {
private static final Logger logger = LoggerFactory.getLogger(ZooKeeperPropertiesApplicationContextInitializer.class);
private final CuratorFramework curator;
private String projectName;
private String projectVersion;
public ZooKeeperPropertiesApplicationContextInitializer() throws IOException {
logger.trace("Attempting to construct CuratorFramework instance");
RetryPolicy retryPolicy = new ExponentialBackoffRetry(10, 100);
curator = CuratorFrameworkFactory.newClient("zookeeper", retryPolicy);
curator.start();
}
/**
* Add a primary property source to the application context, populated from
* a pre-existing ZooKeeper node.
*/
@Override
public void initialize(ConfigurableApplicationContext applicationContext) {
logger.trace("Attempting to add ZooKeeper-derived properties to ApplicationContext PropertySources");
try {
populateProjectProperties();
Properties properties = populatePropertiesFromZooKeeper();
PropertiesPropertySource propertySource = new PropertiesPropertySource("zookeeper", properties);
applicationContext.getEnvironment().getPropertySources().addFirst(propertySource);
logger.debug("Added ZooKeeper-derived properties to ApplicationContext PropertySources");
curator.close();
} catch (IOException e) {
logger.error("IO error attempting to load properties from ZooKeeper", e);
throw new IllegalStateException("Could not load ZooKeeper configuration");
} catch (Exception e) {
logger.error("IO error attempting to load properties from ZooKeeper", e);
throw new IllegalStateException("Could not load ZooKeeper configuration");
} finally {
if (curator != null && curator.isStarted()) {
curator.close();
}
}
}
/**
* Populate the Maven artifact name and version from a property file that
* should be on the classpath, with values entered via Maven filtering.
*
* There is a way of doing these with manifests, but it's a right faff when
* creating shaded uber-jars.
*
* @throws IOException
*/
private void populateProjectProperties() throws IOException {
logger.trace("Attempting to get project name and version from properties file");
try {
ResourcePropertySource projectProps = new ResourcePropertySource("project.properties");
this.projectName = (String) projectProps.getProperty("project.name");
this.projectVersion = (String) projectProps.getProperty("project.version");
} catch (IOException e) {
logger.error("IO error trying to find project name and version, in order to get properties from ZooKeeper");
}
}
/**
* Do the actual loading of properties.
*
* @return
* @throws Exception
* @throws IOException
*/
private Properties populatePropertiesFromZooKeeper() throws Exception, IOException {
logger.debug("Attempting to get properties from ZooKeeper");
try {
byte[] bytes = curator.getData().forPath("/distributed-config/" + projectName + "/" + projectVersion);
InputStream in = new ByteArrayInputStream(bytes);
Properties properties = new Properties();
properties.load(in);
return properties;
} catch (NoNodeException e) {
logger.error("Could not load application configuration from ZooKeeper as no node existed for project [{}]:[{}]", projectName, projectVersion);
throw e;
}
}
}
I was at an Apache Camel talk from James Strachen last week and he mentioned using ZooKeeper under the covers for their Java-based server in the cloud as the source of configuration info.
I've seen a talk from Adrian Colyer (CTO of SpringSource) about runtime config change in Spring, but does Spring support this today?
In my opinion, if you're starting from a typically architected Spring application, I don't see you having an easy job retrofitting dynamic config changes on top of it.
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