CODEWITHSUNDEEP
javaspringspring-bootlogbackslf4j
Onki
Onki

Reputation: 2095

How to select Logback appender based on property file or environment variable

I have configured logback xml for a spring boot project.

I want to configure another appender based on the property configured. We want to create an appender either for JSON logs or for text log, this will be decided either by property file or by environment variable.

So I am thinking about the best approach to do this.

So I want to know if it is possible to add appender at runtime. And will it be added before spring boots up or it could be done anytime in the project.

What could be the best approach to include this scenario.

Upvotes: 3

Views: 7517

Answers (2)

eis
eis

Reputation: 53482

As you're already using Spring, I suggest using Spring Profiles, lot cleaner than trying to do the same programmatically. This approach is also outlined in Spring Boot docs.

You can set an active profile from either property file:

spring.profiles.active=jsonlogs

or from environment value:

spring_profiles_active=jsonlogs

of from startup parameter:

-Dspring.profiles.active=jsonlogs

Then have separate configurations per profile:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <appender name="stdout-classic" class="ch.qos.logback.core.ConsoleAppender">
      <encoder>
          <pattern>%d{dd-MM-yyyy HH:mm:ss.SSS} %magenta([%thread]) %highlight(%-5level) %logger{36}.%M - %msg%n</pattern>
      </encoder>
  </appender>
  <appender name="stdout-json" class="ch.qos.logback.core.ConsoleAppender">
      <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
          <layout class="ch.qos.logback.contrib.json.classic.JsonLayout">
              <timestampFormat>yyyy-MM-dd'T'HH:mm:ss.SSSX</timestampFormat>
              <timestampFormatTimezoneId>Etc/UTC</timestampFormatTimezoneId>
              <jsonFormatter class="ch.qos.logback.contrib.jackson.JacksonJsonFormatter">
                  <prettyPrint>true</prettyPrint>
              </jsonFormatter>
          </layout>
      </encoder>
  </appender>
  <!-- begin profile-specific stuff -->
    <springProfile name="jsonlogs">
        <root level="info">
            <appender-ref ref="stdout-json" />
        </root>
    </springProfile>
    <springProfile name="classiclogs">
        <root level="info">
            <appender-ref ref="stdout-classic" />
        </root>
    </springProfile>
</configuration>

Upvotes: 4

jaguililla
jaguililla

Reputation: 2086

As the previous answer states, you can set different appenders based on Spring Profiles.

However, if you do not want to rely on that feature, you can use environments variables as described in the Logback manual. I.e.:

<appender name="json" class="ch.qos.logback.core.ConsoleAppender">
  <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
    <layout class="ch.qos.logback.contrib.json.classic.JsonLayout">
      <jsonFormatter class="ch.qos.logback.contrib.jackson.JacksonJsonFormatter">
        <prettyPrint>true</prettyPrint>
      </jsonFormatter>
      <appendLineSeparator>true</appendLineSeparator>
    </layout>
  </encoder>
</appender>

<appender name="console" class="ch.qos.logback.core.ConsoleAppender">
  <encoder>
    <pattern>
      %cyan(%d{HH:mm:ss.SSS}) %gray([%thread]) %highlight(%-5level) %magenta(%logger{36}) - %msg%n
    </pattern>
  </encoder>
</appender>

<root level="info">
  <!--
   ! Use the content of the LOGBACK_APPENDER environment variable falling back
   ! to 'json' if it is not defined
   -->
  <appender-ref ref="${LOGBACK_APPENDER:-json}"/>
</root>

Upvotes: 4

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