springboot本地配置覆盖apollo配置

1.apollo包的版本(2.0.0)

<dependency>
    <groupId>com.ctrip.framework.apollo</groupId>
    <artifactId>apollo-client</artifactId>
    <version>2.0.0</version>
</dependency>
<dependency>
    <groupId>com.ctrip.framework.apollo</groupId>
    <artifactId>apollo-core</artifactId>
    <version>2.0.0</version>
</dependency>

2.apollo配置的优先级源码解析

主要是两个文件：com.ctrip.framework.apollo.spring.boot.ApolloApplicationContextInitializer和com.ctrip.framework.apollo.spring.config.PropertySourcesProcessor

(1)ApolloApplicationContextInitializer.class

会将apollo配置放到environment的first，如下代码environment.getPropertySources().addFirst(composite):

@Override
  public void initialize(ConfigurableApplicationContext context) {
    ConfigurableEnvironment environment = context.getEnvironment();

    if (!environment.getProperty(PropertySourcesConstants.APOLLO_BOOTSTRAP_ENABLED, Boolean.class, false)) {
      logger.debug("Apollo bootstrap config is not enabled for context {}, see property: ${{}}", context, PropertySourcesConstants.APOLLO_BOOTSTRAP_ENABLED);
      return;
    }
    logger.debug("Apollo bootstrap config is enabled for context {}", context);

    initialize(environment);
  }


  /**
   * Initialize Apollo Configurations Just after environment is ready.
   *
   * @param environment
   */
  protected void initialize(ConfigurableEnvironment environment) {

    if (environment.getPropertySources().contains(PropertySourcesConstants.APOLLO_BOOTSTRAP_PROPERTY_SOURCE_NAME)) {
      //already initialized, replay the logs that were printed before the logging system was initialized
      DeferredLogger.replayTo();
      return;
    }

    String namespaces = environment.getProperty(PropertySourcesConstants.APOLLO_BOOTSTRAP_NAMESPACES, ConfigConsts.NAMESPACE_APPLICATION);
    logger.debug("Apollo bootstrap namespaces: {}", namespaces);
    List<String> namespaceList = NAMESPACE_SPLITTER.splitToList(namespaces);

    CompositePropertySource composite;
    final ConfigUtil configUtil = ApolloInjector.getInstance(ConfigUtil.class);
    if (configUtil.isPropertyNamesCacheEnabled()) {
      composite = new CachedCompositePropertySource(PropertySourcesConstants.APOLLO_BOOTSTRAP_PROPERTY_SOURCE_NAME);
    } else {
      composite = new CompositePropertySource(PropertySourcesConstants.APOLLO_BOOTSTRAP_PROPERTY_SOURCE_NAME);
    }
    for (String namespace : namespaceList) {
      Config config = ConfigService.getConfig(namespace);

      composite.addPropertySource(configPropertySourceFactory.getConfigPropertySource(namespace, config));
    }

    environment.getPropertySources().addFirst(composite);
  }

(2)PropertySourcesProcessor.class

会再次将apollo配置放到first，如下代码中的environment.getPropertySources().addFirst(composite)和propertySources.addFirst(bootstrapPropertySource):

@Override
  public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
    this.configUtil = ApolloInjector.getInstance(ConfigUtil.class);
    initializePropertySources();
    initializeAutoUpdatePropertiesFeature(beanFactory);
  }

  private void initializePropertySources() {
    if (environment.getPropertySources().contains(PropertySourcesConstants.APOLLO_PROPERTY_SOURCE_NAME)) {
      //already initialized
      return;
    }
    CompositePropertySource composite;
    if (configUtil.isPropertyNamesCacheEnabled()) {
      composite = new CachedCompositePropertySource(PropertySourcesConstants.APOLLO_PROPERTY_SOURCE_NAME);
    } else {
      composite = new CompositePropertySource(PropertySourcesConstants.APOLLO_PROPERTY_SOURCE_NAME);
    }

    //sort by order asc
    ImmutableSortedSet<Integer> orders = ImmutableSortedSet.copyOf(NAMESPACE_NAMES.keySet());
    Iterator<Integer> iterator = orders.iterator();

    while (iterator.hasNext()) {
      int order = iterator.next();
      for (String namespace : NAMESPACE_NAMES.get(order)) {
        Config config = ConfigService.getConfig(namespace);

        composite.addPropertySource(configPropertySourceFactory.getConfigPropertySource(namespace, config));
      }
    }

    // clean up
    NAMESPACE_NAMES.clear();

    // add after the bootstrap property source or to the first
    if (environment.getPropertySources()
        .contains(PropertySourcesConstants.APOLLO_BOOTSTRAP_PROPERTY_SOURCE_NAME)) {

      // ensure ApolloBootstrapPropertySources is still the first
      ensureBootstrapPropertyPrecedence(environment);

      environment.getPropertySources()
          .addAfter(PropertySourcesConstants.APOLLO_BOOTSTRAP_PROPERTY_SOURCE_NAME, composite);
    } else {
      environment.getPropertySources().addFirst(composite);
    }
  }

  private void ensureBootstrapPropertyPrecedence(ConfigurableEnvironment environment) {
    MutablePropertySources propertySources = environment.getPropertySources();

    PropertySource<?> bootstrapPropertySource = propertySources
        .get(PropertySourcesConstants.APOLLO_BOOTSTRAP_PROPERTY_SOURCE_NAME);

    // not exists or already in the first place
    if (bootstrapPropertySource == null || propertySources.precedenceOf(bootstrapPropertySource) == 0) {
      return;
    }

    propertySources.remove(PropertySourcesConstants.APOLLO_BOOTSTRAP_PROPERTY_SOURCE_NAME);
    propertySources.addFirst(bootstrapPropertySource);
  }

3.修改方式

因为在该版本源码中没有看到通过配置修改来达到本地配置覆盖apollo配置的方式，因此可通过在本地增加同名文件再修改代码来覆盖上述的两个文件，具体如下:

这样即将apollo配置的级别调到最低，然后在application.yml中配置的数据会覆盖apollo中的配置

4.apollo-client 2.1.0(新加了是否覆盖系统配置的参数)

相同的文件内都添加如下代码:

查看configUtil.isOverrideSystemProperties()的源码

public boolean isOverrideSystemProperties() {
    return overrideSystemProperties;
  }

  private void initOverrideSystemProperties() {
    overrideSystemProperties = getPropertyBoolean(ApolloClientSystemConsts.APOLLO_OVERRIDE_SYSTEM_PROPERTIES,
            ApolloClientSystemConsts.APOLLO_OVERRIDE_SYSTEM_PROPERTIES,
            overrideSystemProperties);
  }

public static final String APOLLO_OVERRIDE_SYSTEM_PROPERTIES = "apollo.override-system-properties";

即能通过apollo.override-system-properties来实现系统配置来覆盖apollo配置