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log4j2 RollingFile only keeping 4 days

I tried setting up log4j to compress my log files and send them to a mount. I added a day/month/year to it in an attempt to get it in directories like that.
At first this appeared to be working.
Coming back a while later, it turns out only the most recent 4 days are present.
This is my config:
<Configuration>
<Appenders>
<Console name="STDOUT" target="SYSTEM_OUT">
<PatternLayout>
<Pattern>
%d{yyyy-MM-dd HH:mm:ss.SSS} %-5p (%t) %c{1.} %m%n
</Pattern>
</PatternLayout>
</Console>
<RollingFile
name="RollingFile"
fileName="$/home/myservice/myservice.log"
filePattern="/mnt/logbackups/$${date:dd-MM-yyyy}/myservice-%d{dd-MM-yyyy}-%i.log.gz" >
<PatternLayout>
<Pattern>
%d{yyyy-MM-dd HH:mm:ss.SSS} %-5p (%t) %c{1.} %m%n
</Pattern>
</PatternLayout>
<Policies>
<OnStartupTriggeringPolicy />
<SizeBasedTriggeringPolicy size="32 MB"/>
</Policies>
</RollingFile>
</Configuration>
I tried looking for a cause in the documentation: https://logging.apache.org/log4j/2.x/manual/appenders.html
But I can't find anything. Then again it's a gigantic page, maybe I'm missing something.
Does anybody know why this is happening?

You defined the RollingFileAppender which will regularly write to a new logfile. You also defined the triggers when to write to a new file, but you did not set the Rollover Strategies.
You could use the DirectWrite Rollover Strategy with maxFiles not set (to a value greater than zero).
You could also try to configure the Log Archive Retention Policy/Delete on Rollover action. Set testMode=true to prevent any file from being deleted.
Examples are available on the huge page you mentioned.

What you looking for is the "Default Rollover Strategy" specified under Rollover Policies. You can add one explicitly to adjust the default parameters.
Specify it like this inside the RollingFile:
<DefaultRolloverStrategy max="20"/>
Although I am confused because according to their documentation the default is 7:
max | integer | The maximum value of the counter. Once this values is reached older archives will be deleted on subsequent rollovers. The default value is 7

log4j to log4j2 custom RollingPolicy

We have a custom rolling policy that is declared in log4j like this:
log4j.appender.testing.rollingPolicy=com.custom.appender.TimeBasedRollingPolicy
log4j.appender.testing.rollingPolicy.timeToRolloverInSeconds=60
log4j.appender.testing.rollingPolicy.FileNamePattern=/tmp/cdr.log
How can this be declared in log4j2.xml?

Log4j2 has a built-in time based rollover policy that may do what you want. The below configuration results in a rollover every minute:
<Appenders>
<RollingFile name="RollingFile" fileName="logs/app.log"
filePattern="logs/old/app-%d{yyyyMMdd-HHmm}-log.gz">
<PatternLayout>
<Pattern>%d %p %c{1.} [%t] %m%n</Pattern>
</PatternLayout>
<Policies>
<TimeBasedTriggeringPolicy />
</Policies>
</RollingFile>
If you want to create a custom rollover policy, you would need to create a log4j2 plugin that implements TriggeringPolicy. A good starting point would be to look at the source code for the built-in TimeBasedTriggeringPolicy. General information on Log4j custom plugins is here.

Log4j2 - Asynclogger Rolling File Appender not rolling daily per hour

This is my log4j2.xml
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="OFF">
<Appenders>
<!-- Generate STDOUT in console -->
<Console name="CONSOLE" target="SYSTEM_OUT">
<PatternLayout pattern="%d %-5p [%t] %C{2} (%F:%L) - %m%n" />
</Console>
<!-- Generate rolling log for router with per hour interval policy -->
<RollingFile name="RouterRollingFile" fileName="/apps/bea/mb-logs/router.log"
immediateFlush="false" filePattern="/apps/bea/mb-logs/router.%d{yyyy-MM-dd-HH}-%i.log">
<PatternLayout>
<pattern>%d{yyyy-MM-dd HH:mm:ss} %5p [%t] (%F:%L) - %m%n</pattern>
</PatternLayout>
<Policies>
<TimeBasedTriggeringPolicy interval="1" modulate="true"/>
</Policies>
<!-- <DefaultRolloverStrategy fileIndex="max" max="24" /> -->
</RollingFile>
</Appenders>
<Loggers>
<AsyncLogger name="com.tritronik.mb.router" level="info"
additivity="false" includeLocation="true">
<AppenderRef ref="RouterRollingFile" />
</AsyncLogger>
<!-- <Root level="info">
<appender-ref ref="CONSOLE" />
</Root> -->
</Loggers>
I want to achieve daily rolling file with per hour rolling, so far I haven't been able to produce the log with proper format, and as I remember, the interval parameter seems like to increment by day not hour.
I want to achieve this:
router.log --> currently written file
router.log.2014-06-20-00
router.log.2014-06-20-01
...
router.log.2014-06-20-23
router.log.2014-06-21-00
...
Instead I achieve this:
router.log
router.log.2014-06-20-1 --> One day worth of logs
I've been able to do this using usual log4j, but the io performance goes down and force me to use log4j2, but I stumble into this problem.
Where do I have it wrong? Or is it true that log4j2 doesn't support this yet?
Thank you

You may have found a bug.
Is this only happening with Async Loggers or also when you configure a plain (synchronous) logger?
Also, have you tried using a filePattern that looks like this:
filePattern="/apps/bea/mb-logs/$${date:yyyy-MM-dd}/router.%d{yyyy-MM-dd-HH}.log"?
I have a (admittedly vague) suspicion that the $${date:...} part might be related.
If neither of the above makes any difference, could you please file a Jira ticket on the log4j2 issue tracker? https://issues.apache.org/jira/browse/LOG4J2

Time based triggering policy in log4j2

I am trying to create new log files on an hourly basis. I am using TimeBasedTriggerringPolicy of lo4j2 in RollingFileAppender. Below is the sample xml configuration code i have taken from log4j2 official site.
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="warn" name="MyApp" packages="">
<Appenders>
<RollingFile name="RollingFile" fileName="logs/app.log" filePattern="logs/$${date:yyyy-MM}/app-%d{yyyy-MM-dd-HH}-%i.log.gz">
<PatternLayout>
<Pattern>%d %p %c{1.} [%t] %m%n</Pattern>
</PatternLayout>
<Policies>
**
<TimeBasedTriggeringPolicy interval="1" modulate="true" />
**
<SizeBasedTriggeringPolicy size="250 MB" />
</Policies>
</RollingFile>
</Appenders>
<Loggers>
<Root level="error">
<AppenderRef ref="RollingFile" />
</Root>
</Loggers>
</Configuration>
In the interval attribute I have set 1 which signifies 1 hour.
But still my file does not roll every 1 hour.
Please help me find any mistake.
Note : I have included beta9 of log4j2 (which is the latest)

1 here indicates 1 day and not 1 hour. I have manually tested with below configuration.
<RollingFile name="T" fileName="/data_test/log/abc.log"
filePattern="/data_test/log/abc-%d{MM-dd-yyyy}-%i.log">
<PatternLayout>
<Pattern>%d{ISO8601} %-5p [%t] (%F:%L) - %m%n</Pattern>
</PatternLayout>
<Policies>
<TimeBasedTriggeringPolicy interval="1" modulate="true"/>
<SizeBasedTriggeringPolicy size="100 KB" />
</Policies>
</RollingFile>
For manual testing, I change the system date and time.
First, try with increasing 1 hour. The log files will be generated but not as per the expectation.
Then change the system date, increase by 1 day and then see the results.
Suppose the last log file (abc.log) on day 29-Oct is of 50 KB. Configuration size is 100 KB. If we change the day (increase by 1 day) and then run.
Then, last file will be renamed 29-Oct-(some sequence number).log (50 KB file as it is copied) and new file will be created with abc.log
I have tried this with simple servlet with below configuration in web.xml
<context-param>
<param-name>log4jConfiguration</param-name>
<param-value>log4j2.xml</param-value>
</context-param>
keep log4j2.xml in src folder. log4j2.xml is not loaded if we keep it in classpath.

Log4j documentations:
interval -> (integer) How often a rollover should occur based on the most
specific time unit in the date pattern. For example, with a date
pattern with hours as the most specific item and and increment of 4
rollovers would occur every 4 hours. The default value is 1.
You should change the filename pattern if you would like to create it every hour.

As Abid mentioned, interval value is interpreted in context of pattern that is specified as part of filePattern. It starts with lowest denomination. For example,if pattern contains S, frequency will be in millisecond. It supports the date pattern as described in detail as part of SimpleDateFormat java doc http://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html

You do have a non-empty log file (otherwise there is nothing to roll over)?
Note that even though the name is "TimeBased..." It will not actually roll over at the specified time, but at the first log event that arrives after the time threshold has been exceeded. Can you try with a small test program that logs something after 61 minutes or so and see if the problem still occurs?
If it doesn't roll over with the above test program, you may have found a bug. In that case please raise it on the log4j issue tracker. (Be sure to attach the test program the team can use to reproduce the issue).

Everyday day Rolling
<RollingFile name="RollingFile" fileName="logs/app.log"
filePattern="logs/app.%d{yyyy-MM-dd}.log" ...>
...
<TimeBasedTriggeringPolicy interval="1" modulate="true" />
Everyday Hour Rolling
<RollingFile name="RollingFile" fileName="logs/app.log"
filePattern="logs/app.%d{yyyy-MM-dd-HH}.log" ...>
...
<TimeBasedTriggeringPolicy interval="1" modulate="true" />
Everyday 5 day Rolling
<RollingFile name="RollingFile" fileName="logs/app.log"
filePattern="logs/app.%d{yyyy-MM-dd}.log" ...>
...
<TimeBasedTriggeringPolicy interval="5" modulate="true" />
Everyday 5 hours Rolling
<RollingFile name="RollingFile" fileName="logs/app.log"
filePattern="logs/app.%d{yyyy-MM-dd-HH}.log" ...>
...
<TimeBasedTriggeringPolicy interval="5" modulate="true" />
Every Month Rolling
<RollingFile name="RollingFile" fileName="logs/app.log"
filePattern="logs/app.%d{yyyy-MM}.log" ...>
...
<TimeBasedTriggeringPolicy interval="1" modulate="true" />
Hope these cases will helps very well in understanding how filePattern and interval are related.

The time interval interpretation depends on file pattern you are using. The following configuration rolls file every second for me.
<?xml version="1.0" encoding="UTF-8"?>
<Configuration>
<Appenders>
<Console name="A" target="SYSTEM_OUT">
<PatternLayout pattern="%d [%t] %-5p {%F:%L} %x - %m%n" />
<ThresholdFilter level="INFO" onMatch="ACCEPT" onMismatch="DENY"/>
</Console>
<RollingFile name="R"
fileName="/home/xxx/yyy/myapp.log" filePattern="/home/xxx/yyy/myapp-%d{yyyy-MM-dd-HH-mm-ss}-%i.log">
<PatternLayout pattern="%d [%t] %-5p {%F:%L} %x - %m%n" />
<Policies>
<TimeBasedTriggeringPolicy interval="1" />
</Policies>
</RollingFile>
</Appenders>
<Loggers>
<Root level="INFO">
<AppenderRef ref="A" />
<AppenderRef ref="R" />
</Root>
</Loggers>
</Configuration>

According to your TimeBasedTriggeringPolicy configuration, logger will only populate the logs every day not every hour.
AFAIK,You can achieve the functionality by changing the filePattern from HH(Hours) to dd(Days).
I have modified your config.xml. Try This
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="warn" name="MyApp" packages="">
<Appenders>
<RollingFile name="RollingFile" fileName="logs/app.log" filePattern="logs/$${date:yyyy-MM}/app-%d{yyyy-MM-dd}-%i.log.gz">
<PatternLayout>
<Pattern>%d %p %c{1.} [%t] %m%n</Pattern>
</PatternLayout>
<Policies>
**
<TimeBasedTriggeringPolicy interval="1" modulate="true" />
**
<SizeBasedTriggeringPolicy size="250 MB" />
</Policies>
</RollingFile>
</Appenders>
<Loggers>
<Root level="error">
<AppenderRef ref="RollingFile" />
</Root>
</Loggers>
</Configuration>
For more details check this
Hope this will workout for you too.

How to add/subtract date in log4j 2?

i have following configuration file in log4j 2
<RollingFile name="RollingFile" fileName="logs/test.log"
filePattern="logs$${date:yyyyMM}/app-%d{MM-dd-yyyy}.log">
<PatternLayout pattern="%d %-5p [%t] %C{4} (%F:%L) - %m%n"/>
<Policies>
<OnStartupTriggeringPolicy />
<SizeBasedTriggeringPolicy size="20 MB"/>
</Policies>
<DefaultRolloverStrategy fileIndex="max" max="100"/>
</RollingFile>
can I perform date addition and/or subtraction in the filePattern. ? as of now the files generated upon rollover has current date. I would like to subtract single day from it . how can it be done ?

This is currently not possible, but I believe someone requested something similar earlier. I believe filing your request on the Log4j-2.0 issue tracker ( https://issues.apache.org/jira/browse/LOG4J2 ) may be the best way to proceed.