Log through Logback instead of java.util.logging#

Swap the logging backend eezo, Jetty and HikariCP share by default for Logback, without ending up with two providers on the classpath.

How it logs by default#

eezo writes its own lines through the JDK's System.Logger. Jetty and HikariCP write theirs through SLF4J. eezo-http and eezo-db each ship slf4j-jdk14 at runtime, which sends the SLF4J lines to java.util.logging too, so all three share one format on stderr with nothing configured.

Two changes, together#

libraryDependencies += "io.eezo" %% "eezo" % eezoVersion
excludeDependencies += ExclusionRule("org.slf4j", "slf4j-jdk14")
libraryDependencies += "org.slf4j" % "slf4j-jdk-platform-logging" % "2.0.17"
libraryDependencies += "ch.qos.logback" % "logback-classic" % logbackVersion

The exclusion takes slf4j-jdk14 off the classpath. slf4j-jdk-platform-logging hands eezo's System.Logger lines to SLF4J, so they end up in Logback with everything else.

The exclusion is one rule for the whole project, not an exclusion on the eezo line, because eezo-auth, eezo-live and eezo-testkit all reach eezo-http and would bring the binding back.

The warning that means a step was missed#

Adding Logback without the exclusion leaves two SLF4J providers on the classpath, slf4j-jdk14 and logback-classic, and SLF4J says so at every boot. Add the exclusion.

Levels#

The loggers to tune in logback.xml:

<logger name="io.eezo" level="INFO"/>
<logger name="org.eclipse.jetty" level="WARN"/>
<logger name="com.zaxxer.hikari" level="WARN"/>