logback creates new file every prog restart

Question

I have such logback.xmp conf:

<configuration scan="true" scanPeriod="10 seconds" >

<appender name="FILE" class="ch.qos.logback.core.FileAppender">
    <file>${application.home:-.}/logs/application.log</file>
    <filter class="ch.qos.logback.classic.filter.ThresholdFilter">
        <level>DEBUG</level>
    </filter>
    <encoder>
        <pattern>[%d{HH:mm:ss}] [%level] - %message%n%xException</pattern>
    </encoder>
</appender>

<logger name="play" level="WARN"/>
<logger name="application" level="DEBUG"/>

<logger name="org.jdbcdslog.ConnectionLogger" level="OFF"/> <!-- Won' log connections -->
<logger name="org.jdbcdslog.StatementLogger" level="INFO"/> <!-- Will log all statements -->
<logger name="org.jdbcdslog.ResultSetLogger" level="OFF"/> <!-- Won' log result sets -->

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

</configuration>

Every time I restart my prog it creates new log file, but in my way I want to continue write logs into old one. So, what is the problem?

Answer 1

I think you need to use the append property.

Append to or truncate the file? The default value for this variable is true, meaning that by default a FileAppender will append to an existing file and not truncate it.

For example:

<appender name="FILE" class="ch.qos.logback.core.FileAppender">
    <file>${application.home:-.}/logs/application.log</file>
    <filter class="ch.qos.logback.classic.filter.ThresholdFilter">
        <level>DEBUG</level>
    </filter>
    <encoder>
        <pattern>[%d{HH:mm:ss}] [%level] - %message%n%xException</pattern>
    </encoder>
    <append>true</append>
</appender>

However, since (according to the javadoc ... and the current version's source code) the append property defaults to true, it is unclear why you would need to do this¹.

Note that setting prudent to true also sets append to true.

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^{1 - Unless ... perhaps ... you are running into a Windows file locking issue?}