Allow subclasses to insert custom fields

[echatman]

Protected method that subclasses can override to insert arbitrary custom fields in the logback encoder. https://github.com/elastic/ecs-logging-java/issues/147

[apmmachine]

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#### Build stats * Start Time: 2021-10-19T06:25:44.818+0000 * Duration: 5 min 23 sec * Commit: 3ca0dca6b32298ecb4ec72a6adf01afc17ee7d9b #### Test stats :test_tube: | Test | Results | | ------------ | :-----------------------------: | | Failed | 0 | | Passed | 171 | | Skipped | 0 | | Total | 171 |

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[felixbarny]

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[felixbarny]

Thank you!

[lbuyse]

Hello ,

I need exactly the same functionality. Allthough i can't get my custom EcsEncoder extension class to work with spring boot and logback. Can i find an example of class like this somewhere ... ? i am wondering if overriding the addCustomFields method is enough.

Many thanks

[echatman]

Yes you just create a class that extends EcsEncoder and override the addCustomFields method to add in whatever you need. Then you use it by defining your own custom appender - you can copy from ecs-console-appender.xml or ecs-file-appender.xml and change the appender name and encoder class.

So a full logback-spring.xml config could look like this:

<configuration>
    <include resource="org/springframework/boot/logging/logback/defaults.xml" />
    <include resource="co/elastic/logging/logback/boot/ecs-console-appender.xml" />
    <appender name="CUSTOM_ECS_JSON_CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
        <encoder class="com.echatman.MyCustomEcsEncoder">
            <serviceName>${SERVICE_NAME:-spring-boot-application}</serviceName>
            <!-- any other properties you want to set on your custom class go here -->
        </encoder>
    </appender>
    <root level="INFO">
        <appender-ref ref="CUSTOM_ECS_JSON_CONSOLE" />
    </root>
</configuration>

[lbuyse]

Hello , Thats exactly what i did but while debugging i've realized i wrote a bug in my custom encoder which caused a nullpointer in my encoder that caused it not to write logs. I solved it and it works as expected , many thanks for your help and sorry to waste your time. Kind regards