增加EnvironmentPostProcessor处理，将Apollo配置加载提到初始化日志系统之前

[LuanLouis]

解决的问题：

将Apollo的配置加载提到Spring 初始化日志系统之前，能够让 logback-spring.xml可以读取到Apollo中的配置数据

目前版本存在的问题：

目前Apollo加载配置信息的时机如下图所示：

目前Apollo加载配置信息的时机比日志系统初始化晚，如果要让logbak-spring.xml文件能够正常读取Apollo的配置，则有两种方案可供选择：

方案一：在ConfigFileApplicationListener 和LoggingApplicationListener之间插入一个监听器，用于初始化Apollo 配置信息；

这种方式在SpringBoot模式下想在这两者之间插入一个Listener 有点问题，Spring Boot 会将添加的Listener踢掉，目前还没弄清楚咋回事；另外这种插入方式和Listener的Order顺序有关，写死顺序不是很优雅；

方案二：实现一个EnvironmentPostProcessor,供ConfigFileApplicationListener在加载好bootstrap.properties 和application.properties之后加载Apollo的配置信息

这种方式比较好些，添加一个EnvironmentPostProcessor实现，然后在spring.factories里面指定即可

org.springframework.boot.env.EnvironmentPostProcessor=\
com.ctrip.framework.apollo.spring.boot.ApolloApplicationContextInitializer

注意：
这种方式使得Apollo的加载顺序放到了日志系统加载之前，会导致Apollo的启动过程无法通过日志的方式输出(因为执行Apollo加载的时候，日志系统压根没有准备好呢！所以在Apollo代码中使用Slf4j的日志输出便没有任何内容)

这种加载时间太靠前的方式不是必选的，通过参数apollo.bootstrap.eagerLoad.enabled可控制是否走这种逻辑：

  /**
   *
   * In order to load  Apollo configurations even as early before Spring loading logging system phase,
   *
   *  This EnvironmentPostProcessor can be called Just After ConfigFileApplicationListener has succeeded.
   *
   *
   *  The processing sequence would be like this:
   *
   *  Load Bootstrap properties and application properties -----> load Apollo configuration properties ----> Initialize Logging systems
   *
   *
   *
   * @param configurableEnvironment
   * @param springApplication
   */
  @Override
  public void postProcessEnvironment(ConfigurableEnvironment configurableEnvironment, SpringApplication springApplication) {

    Boolean eagerLoadEnabled  = configurableEnvironment.getProperty(PropertySourcesConstants.APOLLO_BOOTSTRAP_EAGER_LOAD_ENABLED,Boolean.class,false);


    //EnvironmentPostProcessor should not be triggered if you don't want Apollo Loading before Logging System Initialization
    if(!eagerLoadEnabled){
      return;
    }

    Boolean bootstrapEnabled = configurableEnvironment.getProperty(PropertySourcesConstants.APOLLO_BOOTSTRAP_ENABLED,Boolean.class,false);

    if(bootstrapEnabled) {
        initialize(configurableEnvironment);
    }

  }

[LuanLouis]

#1243

[codecov-io]

Codecov Report

Merging #1614 into master will increase coverage by 7.47%.
The diff coverage is 90%.

@@             Coverage Diff              @@
##             master    #1614      +/-   ##
============================================
+ Coverage     48.71%   56.18%   +7.47%     
+ Complexity     1901     1067     -834     
============================================
  Files           392      191     -201     
  Lines         11483     5656    -5827     
  Branches       1195      591     -604     
============================================
- Hits           5594     3178    -2416     
+ Misses         5459     2237    -3222     
+ Partials        430      241     -189

Impacted Files	Coverage Δ	Complexity Δ
...ring/boot/ApolloApplicationContextInitializer.java	97.72% <90%> (+3.44%)	14 <2> (+4)	⬆️
...ework/apollo/portal/controller/ItemController.java
...o/configservice/wrapper/DeferredResultWrapper.java
...omponent/emailbuilder/GrayPublishEmailBuilder.java
...k/apollo/portal/controller/FavoriteController.java
...apollo/portal/entity/vo/AppRolesAssignedUsers.java
...ponent/emailbuilder/NormalPublishEmailBuilder.java
.../framework/apollo/portal/entity/vo/SystemInfo.java
...rk/apollo/portal/service/NamespaceLockService.java
...k/apollo/portal/spi/ctrip/CtripUserInfoHolder.java
... and 193 more

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[coveralls]

Coverage increased (+0.05%) to 52.506% when pulling f427699 on LuanLouis:pr-eager-load-before-logging into 703398f on ctripcorp:master.

[nobodyiam]

Thanks! Will take a detailed look soon.

[pandalin]

作者看着好眼熟。。。

[nobodyiam]

@LuanLouis

This works great!

However, there is an issue of the executing sequence of initializeSystemProperty, so I submitted a pull request to your repository instead, please have a look - LuanLouis#1

Thank!

[nobodyiam]

Thanks!

[hnotyet]

这个方案解决了logback可以加载到apollo的配置，但是修改apollo无法做到日志参数跟着变，比如修改日志级别。看了springboot关于 logback扩展的文档，如果使用了扩展，logback原本的scan功能将失效，不知道跟这个是否有关系，希望能够优化。原文地址：https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-logging.html#boot-features-logback-extensions

[bugmakesprogress]

这个方案解决了logback可以加载到apollo的配置，但是修改apollo无法做到日志参数跟着变，比如修改日志级别。看了springboot关于 logback扩展的文档，如果使用了扩展，logback原本的scan功能将失效，不知道跟这个是否有关系，希望能够优化。原文地址：https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-logging.html#boot-features-logback-extensions

如果只是日志级别的话，是可以做到动态修改日志级别的。 添加@ApolloConfigChangeListener注解，然后在application这个默认（看看你是不是使用的默认namespace）的namespace里添加对应日志级别即可控制细化到某一类的日志级别。
具体可以参考下下面两个链接：
https://www.jianshu.com/p/7d91cb5109a4
https://blog.csdn.net/qq_31289187/article/details/84346529

[lawrencewu]

@nobodyiam @LuanLouis 测试了springboot 项目(无logback.xml)的情形和spring+logback.xml的情形以及spring+logback-spring.xml的情形, 发现这个配置只在springboot项目下生效, 在spring项目中无效, 是吗?

[nobodyiam]

@lawrencewu apollo.bootstrap.eagerLoad.enabled这个配置是针对Spring Boot生效的

[lawrencewu]

@nobodyiam 有两个问题 1. 那在Spring下有什么办法能让logback.xml读取apollo配置中心里面的内容吗? 如下面配置中的logger_logback_logpath. 2. 在3.2.1.3 Spring Boot集成方式（推荐）中应该是只针对springboot的应用吧, 针对spring应用该如何操作,能不能进一步细化该节的文档?

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <appender name="stdout" class="ch.qos.logback.core.ConsoleAppender">
        <encoder charset="utf-8">
            <Pattern>[%date{yyyy-MM-dd HH:mm:ss}] [%-5level] %logger %line --%mdc{client} %msg%n</Pattern>
        </encoder>
    </appender>

    <appender name="logfile-core" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <File>${logger_logback_logpath}/sample.log</File>
        <encoder>
            <pattern>[%date] [%level] [%logger %line] [%thread] %msg %n</pattern>
            <charset>UTF-8</charset>
            <immediateFlush>false</immediateFlush>
        </encoder>
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <fileNamePattern>${logger_logback_logpath}/sample-%d{yyyy-MM-dd}.%i.log</fileNamePattern>
            <maxHistory>3</maxHistory>
            <TimeBasedFileNamingAndTriggeringPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
                <maxFileSize>512MB</maxFileSize>
            </TimeBasedFileNamingAndTriggeringPolicy>
        </rollingPolicy>
    </appender>
    <appender name="ASYNC" class="ch.qos.logback.classic.AsyncAppender">
        <discardingThreshold >0</discardingThreshold>
        <queueSize>1024</queueSize>
        <includeCallerData>true</includeCallerData>
        <appender-ref ref ="logfile-core"/>
    </appender>

    <logger name="org.apache.commons" level="INFO"/>
    <logger name="org.springframework" level="INFO"/>
    <logger name="org.springframework.web.servlet.DispatcherServlet" level="INFO"/>
    <logger name="org.springframework.web.context.support.XmlWebApplicationContext" level="INFO"/>
    <logger name="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping" level="INFO"/>
    <logger name="java.sql.PreparedStatement" level="INFO"/>
    <logger name="java.sql" level="INFO"/>
    <logger name="java.sql.Statement" level="INFO"/>
    <logger name="java.sql.ResultSet" level="INFO"/>
    <logger name="java.sql.Connection" level="INFO"/>
    <root level="${logging.level.root}">
        <appender-ref ref="ASYNC"/>
        <appender-ref ref="stdout"/>
    </root>
</configuration>