Micronaut configure logger appenders based of the enviroment - logback

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:
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);
}
}
create you custom env based logback config file like: logback-dev.xml and put in resources dir.
the set env var MICRONAUT_ENVIRONMENTS=dev according to your deployment logic.
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.

Answer 3

As far I understand, Micronaut doesn't have similar thing like Spring boot ( ) implemented.
I think logback-production.xml (where production is profile
) doesn't work too - only logback.xml and logback-test.xml is suported.

Answer 4

I wasn't crazy about the idea of having multiple logback config files or pulling in another dependency (janino) to support this use-case.
You can also do this using environment variables.
In my logback.xml I defined 2 appenders, one for "DEV" and one for "PROD".
Then I dynamically select which appender to use via the LOG_TARGET variable. If the variable is not set then it defaults to "DEV".
<configuration>
<appender name="DEV" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%date{ISO8601} %-5level [%X{trace_id},%X{span_id}] [%thread] %logger{36} - %msg%n</pattern>
</encoder>
</appender>
<appender name="PROD" class="ch.qos.logback.core.ConsoleAppender">
<encoder class="net.logstash.logback.encoder.LogstashEncoder" />
</appender>
<appender name="OTEL" class="io.opentelemetry.instrumentation.logback.v1_0.OpenTelemetryAppender">
<appender-ref ref="${LOG_TARGET:-DEV}"/>
</appender>
<root level="info">
<appender-ref ref="OTEL"/>
</root>
</configuration>