Logback file (testlog.log) is not created - spring-boot

Question

I was using slf4j for logging purposes and everything worked well (file was created on a path I specified and all my logs were there), however, due to my requirements I had to make logger use the JSON format. I decided to use Logback for that purpose but my log file is not created (even tho in the console I see logs written in the JSON format - but for some reason file is not created so I can see those logs only in the console)
Here is my setup:
application.properties
logging.level.org.springframework.web=DEBUG
logging.level.org.hibernate=ERROR
logging.file.path=./install/my-project/logs
logging.file.name=${logging.file.path}/testlog.log
POM.xml
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.2.3</version>
</dependency>
<dependency>
<groupId>ch.qos.logback.contrib</groupId>
<artifactId>logback-jackson</artifactId>
<version>${logback.contrib.version}</version>
</dependency>
<dependency>
<groupId>ch.qos.logback.contrib</groupId>
<artifactId>logback-json-classic</artifactId>
<version>${logback.contrib.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.25</version>
</dependency>
logback.xml
<configuration>
<appender name="stdout" class="ch.qos.logback.core.ConsoleAppender">
<encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
<layout class="ch.qos.logback.contrib.json.classic.JsonLayout">
<timestampFormat>yyyy-MM-dd'T'HH:mm:ss.SSSX</timestampFormat>
<timestampFormatTimezoneId>Etc/UTC</timestampFormatTimezoneId>
<jsonFormatter class="ch.qos.logback.contrib.jackson.JacksonJsonFormatter">
<prettyPrint>true</prettyPrint>
</jsonFormatter>
</layout>
</encoder>
</appender>
<root level="debug">
<appender-ref ref="stdout"/>
</root>
</configuration>
So with this setup, I see my logs in the console formatted as JSON, however,log file is not created. If I remove these dependencies, and delete logback.xml file and then I restart my application, then my logging works perfectly (log file is created on a specified location) however it's not a JSON format.
I've tried a lot of different options but I cannot figure out why I'm having this strange problem.
Hope you guys can help me

Answer 1

As "Simon Martinelli" pointed out, I had to add file appender as well so my logback.xml file now looks like this:
<configuration>
<property name="HOME_LOG" value="./install/my-project/logs"/>
<appender name="FILE-ROLLING" class="ch.qos.logback.core.rolling.RollingFileAppender">
<file>${HOME_LOG}</file>
<rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
<fileNamePattern>logs/archived/app.%d{yyyy-MM-dd}.%i.log.gz</fileNamePattern>
<!-- each archived file, size max 10MB -->
<maxFileSize>10MB</maxFileSize>
<!-- total size of all archive files, if total size > 20GB, it will delete old archived file -->
<totalSizeCap>20GB</totalSizeCap>
<!-- 60 days to keep -->
<maxHistory>60</maxHistory>
</rollingPolicy>
<encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
<layout class="ch.qos.logback.contrib.json.classic.JsonLayout">
<timestampFormat>yyyy-MM-dd'T'HH:mm:ss.SSSX</timestampFormat>
<timestampFormatTimezoneId>Etc/UTC</timestampFormatTimezoneId>
<jsonFormatter class="ch.qos.logback.contrib.jackson.JacksonJsonFormatter">
<prettyPrint>true</prettyPrint>
</jsonFormatter>
</layout>
</encoder>
</appender>
<logger name="com.mkyong" level="debug" additivity="false">
<appender-ref ref="FILE-ROLLING"/>
</logger>
<root level="error">
<appender-ref ref="FILE-ROLLING"/>
</root>
<appender name="stdout" class="ch.qos.logback.core.ConsoleAppender">
<encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
<layout class="ch.qos.logback.contrib.json.classic.JsonLayout">
<timestampFormat>yyyy-MM-dd'T'HH:mm:ss.SSSX</timestampFormat>
<timestampFormatTimezoneId>Etc/UTC</timestampFormatTimezoneId>
<jsonFormatter class="ch.qos.logback.contrib.jackson.JacksonJsonFormatter">
<prettyPrint>true</prettyPrint>
</jsonFormatter>
</layout>
</encoder>
</appender>
<root level="debug">
<appender-ref ref="stdout"/>
</root>
</configuration>
Thanks!