Forcing Tomcat to log through SLF4J/Logback
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So you have your executable web application in JAR with bundled Tomcat (make sure to read that one first). However there are these annoying Tomcat logs at the beginning, independent from our application logs and not customizable
Nov 24, 2012 11:44:02 PM org.apache.coyote.AbstractProtocol init INFO: Initializing ProtocolHandler ["http-bio-8080"] Nov 24, 2012 11:44:02 PM org.apache.catalina.core.StandardService startInternal INFO: Starting service Tomcat Nov 24, 2012 11:44:02 PM org.apache.catalina.core.StandardEngine startInternal INFO: Starting Servlet Engine: Apache Tomcat/7.0.30 Nov 24, 2012 11:44:05 PM org.apache.coyote.AbstractProtocol start INFO: Starting ProtocolHandler ["http-bio-8080"]
I would really like to quite them down, or even better save them
somewhere since they sometimes reveal important failures. But I
definitely don't want to have a separate
java.util.logging configuration. Did you wonder after reading the previous article how did I knew that runnable Tomcat JAR supports
-httpPort parameter and few others? Well, I checked the sources, but it's simpler to just ask for help:
$ java -jar target/standalone.jar -help usage: java -jar [path to your exec war jar] -ajpPort <ajpPort> ajp port to use -clientAuth enable client authentication for https -D <arg> key=value -extractDirectory <extractDirectory> path to extract war content, default value: .extract -h,--help help -httpPort <httpPort> http port to use -httpProtocol <httpProtocol> http protocol to use: HTTP/1.1 or org.apache.coyote.http11.Http11Nio Protocol -httpsPort <httpsPort> https port to use -keyAlias <keyAlias> alias from keystore for ssl -loggerName <loggerName> logger to use: slf4j to use slf4j bridge on top of jul -obfuscate <password> obfuscate the password and exit -resetExtract clean previous extract directory -serverXmlPath <serverXmlPath> server.xml to use, optional -uriEncoding <uriEncoding> connector uriEncoding default ISO-8859-1 -X,--debug
-loggerName parameter looks quite promising. First try:
$ java -jar target/standalone.jar -loggerName slf4j WARNING: issue configuring slf4j jul bridge, skip it
No good. Quick look at the source code again and it turns out that SLF4J
library is missing. Since this parameter is interpreted during Tomcat
bootstrapping (way before web application is deployed),
slf4j-api.jar inside my web application is not enough, it has to be available for root class loader (equivalent to
/lib directory in packaged Tomcat). Luckily plugin exposes
<extraDependencies/> configuration parameter:
<configuration> <path>/standalone</path> <enableNaming>false</enableNaming> <finalName>standalone.jar</finalName> <charset>utf-8</charset> <extraDependencies> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> <version>1.7.2</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>jul-to-slf4j</artifactId> <version>1.7.2</version> </dependency> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-classic</artifactId> <version>1.0.7</version> </dependency> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-core</artifactId> <version>1.0.7</version> </dependency> </extraDependencies> </configuration>
Running Tomcat and... success!
00:01:27.110 [main] INFO o.a.coyote.http11.Http11Protocol - Initializing ProtocolHandler ["http-bio-8080"] 00:01:27.127 [main] INFO o.a.catalina.core.StandardService - Starting service Tomcat 00:01:27.128 [main] INFO o.a.catalina.core.StandardEngine - Starting Servlet Engine: Apache Tomcat/7.0.33 00:01:29.645 [main] INFO o.a.coyote.http11.Http11Protocol - Starting ProtocolHandler ["http-bio-8080"]
Well, not quite. If you use Logback on a daily basis you are familiar with default console logging pattern. We are not picking up any
logback.xml. From my experience it seems that placing
externally somewhere in your file system is superior to putting it
inside your binary, especially with auto refreshing feature turned on:
<configuration scan="true" scanPeriod="5 seconds"> <!-- ... --> </configuration>
Put some fallback
logback.xml file in the root of your CLASSPATH in case no other file was specified like below and voilà:
$ java -jar standalone.jar -httpPort=8081 -loggerName=slf4j \ -Dlogback.configurationFile=/etc/foo/logback.xml
Finally, clean and consistent logging, most likely to a single file.
Published at DZone with permission of Tomasz Nurkiewicz, DZone MVB. See the original article here.
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