如何动态(通过env变量)激活/停用logback或logback追加程序? [英] How can I dynamically (by env variable) activate/deactivate logback or logback appender?

问题描述

是否可以通过环境变量选择是否要使用logback追加器?

我有一个dockerized春季启动微服务，现在添加了ELK堆栈.
到目前为止，一切正常.
但是现在，如果我想在没有ELK堆栈的情况下启动服务，该应用程序将引发一个错误，即它不知道Logstash的主机:

is there a way to choose if I want to have a logback appender or not, via environment variable?

I have a dockerized spring boot Microservice and added now the ELK stack.
That works fine so far.
But now if I want to start my service without ELK stack, the application throws an error, that it doesn't know the host of Logstash:

app | 10:09:23,537 |-ERROR in ch.qos.logback.classic.net.SyslogAppender[SYSLOG] - Could not create SyslogWriter java.net.UnknownHostException: logstash: Name or service not known
app |   at java.net.UnknownHostException: logstash: Name or service not known

这是我的logback.xml文件:

Here is my logback.xml file:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>

    <appender name="SYSLOG" class="ch.qos.logback.classic.net.SyslogAppender">
        <syslogHost>logstash</syslogHost>
        <port>5000</port>
        <facility>LOCAL1</facility>
        <suffixPattern>[%thread] %logger %msg</suffixPattern>
    </appender>

    <root level="INFO">
        <appender-ref ref="SYSLOG"/>
    </root>

</configuration>

我知道这是一个非常简单的版本，但是我是使用logback/ELK堆栈进行日志记录的新手.

所以有一种方法可以使用yaml文件中的环境变量注入一些东西. active=${LOGBACK_ACTIVE:false}像我可以使用普罗米修斯指标那样吗?

I know this is a very simple version, but I am new in logging with logback/ELK stack.

So is there a way to inject something with an environment variable like in yaml files e.g. active=${LOGBACK_ACTIVE:false} like I can do it with my prometheus metrics?

推荐答案

在您的logback.xml中，当存在命名的JVM参数时，可以使用<if>构造启用SYSLOG附加程序.

In your logback.xml you could use the <if> construct to enable the SYSLOG appender when a named JVM parameter is present.

在以下示例中，如果使用-Dsyslog运行应用程序，则将使用SYSLOG附加程序，否则它将被忽略，并且将使用默认附加程序CONSOLE:

In the following example if you run your application with -Dsyslog then your SYSLOG appender will be engaged otherwise it will be ignored and the default appender, CONSOLE, will be engaged:

<if condition='isDefined("syslog")'>
  <then>
    <appender name="SYSLOG" class="ch.qos.logback.classic.net.SyslogAppender">
      ...
    </appender>

    <root level="INFO">
      <appender-ref ref="SYSLOG" />
    </root>
  </then>
  <else>
    <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
      ...
    </appender>

    <root level="INFO">
      <appender-ref ref="CONSOLE" />
    </root>
  </else>
</if>

这需要重复root声明，但是由于您需要有条件地防止实例化SYSLOG追加器，我认为这可能是您唯一的选择.

This requires some duplication of the root declaration but since you need to conditionally prevent the SYSLOG appender from being instantiated I think this might be your only option.

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