How to configure log4j and logback to log into one single file properly?

I have a java web app that uses logback with slf4j for logging. And this project has a dependency jar (which is a sub project). And this dependency jar uses org.apache.log4j.Logger for logging. All logs must go into one log file. My problem is, whatever I am logging with the code in the jar file is not being written to the log file. Initially I had logback.xml. To resolve the above problem I added log4j.properties file to my web app. It resolved my problem and now I can see all logs in one file.

Again my new probelm is: Earlier the log file was rolling every day according to the rolling policy in logback.xml. Now it is not rolling. Even after I configured the rolling policy in log4j.properties that matches with the rolling policy that is in logback.xml, rolling is not happening.

I don't want to replace log4j in my dependency with logback. And also I want to write alll my logs into one file. Is it possible to this, how can I resolve my issue?

FYI: I have "log4j-over-slf4j" dependency included in my pom.xml

Log4j.properties:

log4j.appender.file=org.apache.log4j.DailyRollingFileAppender
log4j.appender.file.File=SOME_PATH/logs/studentApp.log
log4j.appender.file.rollingPolicy = org.apache.log4j.rolling.TimeBasedRollingPolicy
log4j.appender.file.rollingPolicy.FileNamePattern = SOME_PATH/logs/studentApp.%d{yyyy-MM-dd}.log    
log4j.appender.file.maxBackupIndex=14
log4j.appender.file.threshold=DEBUG
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=[%-5p] %d %c - %m%n
log4j.rootLogger=DEBUG,file

Solution

Assuming your rolling policy is correct, it's possible that log4j picks up the wrong configuration. log4j looks for the first configuration file in the classpath (first .xml then .properties) and if it happens to be the configuration from one of your dependencies your rolling policy will not work.

To test this you can add a system property -Dlog4j.configuration=... with the path to your configuration to the tomcat startup script. Or simply set your log level to TRACE/DEBUG and see if it affects the output.

Edit: your log4j config looks good, but the date pattern is missing. Try adding log4j.appender.file.DatePattern='.'yyyy-MM-dd-HH-mm (note that I've set the pattern to roll-over every minute, for easier testing)

Edit: you can remove every line containing rollingPolicy and maxBackupIndex - those will not be picked up in this case