Micronaut configure logger appenders based of the enviroment

Question

I would like to configure logging appender based on the environment, for example while running in production I would like to configure an appender that would send log to elasticsearch but while on test or development mode this appender would not be enabled.

Answer 1

You can override the default logback config file by using "logback.configurationFile" system variable.

java -Dlogback.configurationFile=logback-prod.xml -jar your.jar

But, if what you need is the ability to use an env variable you can do this without to use a third-party library:

1. Override the logback system variable inside the main micronaut class before call main, like following

    @Singleton
    public class MyMicronautApplication  {
   
        public static void main(String[] args) {
            var env = System.getenv("MICRONAUT_ENVIRONMENTS");
   
            if (env != null && !env.isEmpty()) {
                System.setProperty(ContextInitializer.CONFIG_FILE_PROPERTY, "logback-" + env + ".xml");
            }
   
            Micronaut.run(MyMicronautApplication.class);
   
        }
    }
   

2. create you custom env based logback config file like: logback-dev.xml and put in resources dir.

3. the set env var MICRONAUT_ENVIRONMENTS=dev according to your deployment logic.

4. enjoy using logback-dev.xml, logback-prod.xml, logback-stagging.xml, etc

Answer 2

The work around i found was by doing conditional expressions in logback. You will need the following dependency

<!-- https://mvnrepository.com/artifact/org.codehaus.janino/janino -->
<dependency>
    <groupId>org.codehaus.janino</groupId>
    <artifactId>janino</artifactId>
    <version>3.1.2</version>
</dependency>

Then in your logback.xml file, you can do a conditional statement such as following for selecting the appender you want to you use based on a micronaut profile. In my case, I wanted to activate the STDOUT appender if i was running the application locally but i did not want to activate the STDOUT profile if the app was running in any other environment such as dev or prod profiles, instead i wanted the RSYSLOG appender to be used.

    <root level="info">
        <if condition='property("MICRONAUT_ENVIRONMENTS").contains("local")'>
            <then>
                <appender-ref ref="STDOUT"/>
            </then>
            <else>
                <appender-ref ref="RSYSLOG"/>
            </else>
        </if>
    </root>

You can use conditional statements to configure other properties in your logback file.