LOGBACK：将日志写入类路径中的文件

Question

I've recently started with Logback and was going through the official documentation. While implementing it in one of my projects, I was wondering if there was a way to write the logs to a file on the classpath or somewhere within the target folder/logs/myapp.log? I could not find much information on the official documentation (yes, I've read variable substitution).

Here's my logback.xml:

    <appender name="FILE" class="ch.qos.logback.core.FileAppender">
        <file>clientLog.log</file>
        <append>true</append>
        <!-- encoders are assigned the type ch.qos.logback.classic.encoder.PatternLayoutEncoder 
            by default -->
        <encoder>
            <pattern>%-4relative [%thread] %-5level %logger{35} - %msg%n
            </pattern>
        </encoder>
    </appender>


    <root level="INFO">
        <appender-ref ref="FILE" />

    </root>

</configuration>

Now I want the clientLog.log file to be created inside the target folder (MAVEN project). Any pointers will be appreciated.

Answer 1

I doubt that you will find a standard mechanism to write to a file on the application's classpath. The stuff on the classpath is typically read-only.

Similarly you won't find a mechanism that explicitly supports a log in some location in the build environment (eg a "target" directory). Applications typically don't run in the build environment.

So the most practical solution is probably to have two separate logging configuration files; ie one for your development platform and another for your deployment platform. Use different log file pathnames in the different logging config files.

---

If the relative pathname target/logs/clientLog.log is not working, then the chances are that something is changing the "current directory" when the your application (eg the tomcat server) is launching. But (AFAIK) that is normal for Tomcat.

Answer 2

If I understood your question then I guess you can achieve your task by setting your path as an environment variable. Here are the things you have to do :

1. create one variable, say "LOGDIR" in your logback.xml file

<property name="LOGDIR" value="${app.workdir}/log" />

2. In FILE APPENDER, add file path as :

<File>${LOGDIR}/${FILE_NAME}-${bySecond}.log</File>

Here your file will get created under the $LOGDIR directory. Now the question is how to set "LOGDIR" value.

In your JAVA application, SET app.workdir as the System variable i,e

System.setProperty("app.workdir", "YOUR_TARGET_PATH")

Let me know if you got confused.

Answer 3

if you use mac please use the absolute path like ${catalina.base}/userLog.%d{yyyy-MM-dd}.log under tomcat

it won't work with the relative path like ../userLog.%d{yyyy-MM-dd}.log so i think it is always good to use some variable