why springboot clear the old log configuration when starts up

Question

There is a legacy application which uses JUL and registers handlers via code. Now I use springboot within the legacy app.

I tried with minimum spring boot dependency which only includes spring-boot-starter and excludes spring-boot-starter-logging; set org.springframework.boot.logging.LoggingSystem to none in application.properties; use either commons-logging or jcl-over-slf4j. And JUL configuration is always cleared when spring boot starts up.

Is there a way to keep JUL configuration no change when spring boot starts up?

The spring boot version is 1.5.20 due to the legacy app is compiled with java7

all properties defined in logging.properties are lost; all handlers registered via code are lost. with LogManager.getLogManager().getLogger("").getHandlers() can see the difference before/after spring boot starts up — yk42b

yk42b yk42b · Accepted Answer · 2019-09-16T08:25:02

this link partially answers the question

However, still not sure the mechanism of Logger initialization of Spring Boot

why springboot clear the old log configuration when starts up

1 Answers