fix: log4j properties files (#4293)

* fix: log4j properties files

This PR removes the log4j.properties files from our production jars. The presence of such files will make it more tricky for clients to correctly configure log4j with their own properties files as log4j picks the first it finds on the class path by default.

Also, changed many log levels from `ERROR` to `WARN` as important warnings are being excluded, which could be hiding issues.

config/log4j-rolling.properties

@@ -46,22 +46,34 @@ log4j.appender.kafka_appender.BrokerList=localhost:9092
 log4j.appender.kafka_appender.Topic=default_ksql_processing_log
 
 # loggers
+
+log4j.logger.org.reflections=ERROR, main
+
+# Uncomment the following line to stop KSQL from logging out each request it receives:
+#log4j.logger.io.confluent.ksql.rest.server.resources.KsqlResource=WARN
+
+# And this one to avoid the logs being spammed with KsqlConfig values.
+# Though these can be useful for debugging / investigations.
+#log4j.logger.io.confluent.ksql.util.KsqlConfig=WARN
+
+## KSQL Processing logs:
+log4j.logger.processing=WARN, kafka_appender
+log4j.additivity.processing=false
+
+## Kafka Streams logs:
 log4j.logger.org.apache.kafka.streams=INFO, streams
 log4j.additivity.org.apache.kafka.streams=false
 
-log4j.logger.kafka=ERROR, kafka
+## Kafka client logs:
+log4j.logger.kafka=WARN, kafka
 log4j.additivity.kafka=false
 
-log4j.logger.org.apache.zookeeper=ERROR, kafka
+log4j.logger.org.apache.zookeeper=WARN, kafka
 log4j.additivity.org.apache.zookeeper=false
 
-log4j.logger.org.apache.kafka=ERROR, kafka
+log4j.logger.org.apache.kafka=WARN, kafka
 log4j.additivity.org.apache.kafka=false
 
-log4j.logger.org.I0Itec.zkclient=ERROR, kafka
+log4j.logger.org.I0Itec.zkclient=WARN, kafka
 log4j.additivity.org.I0Itec.zkclient=false
 
-log4j.logger.processing=ERROR, kafka_appender
-log4j.additivity.processing=false
-
-log4j.logger.org.reflections=ERROR, main

config/log4j.properties

@@ -15,6 +15,7 @@
 
 log4j.rootLogger=INFO, stdout
 
+# appenders
 log4j.appender.stdout=org.apache.log4j.ConsoleAppender
 log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
 log4j.appender.stdout.layout.ConversionPattern=[%d] %p %m (%c:%L)%n
@@ -23,13 +24,23 @@ log4j.appender.streams=org.apache.log4j.ConsoleAppender
 log4j.appender.streams.layout=org.apache.log4j.PatternLayout
 log4j.appender.streams.layout.ConversionPattern=[%d] %p %m (%c:%L)%n
 
-log4j.logger.kafka=ERROR, stdout
-log4j.logger.org.apache.kafka.streams=INFO, streams
-log4j.additivity.org.apache.kafka.streams=false
-log4j.logger.org.apache.zookeeper=ERROR, stdout
-log4j.logger.org.apache.kafka=ERROR, stdout
-log4j.logger.org.I0Itec.zkclient=ERROR, stdout
+# loggers
+
 log4j.logger.org.reflections=ERROR, stdout
 
 # Uncomment the following line to stop KSQL from logging out each request it receives:
-#log4j.logger.io.confluent.ksql.rest.server.resources.KsqlResource=WARN, stdout
+#log4j.logger.io.confluent.ksql.rest.server.resources.KsqlResource=WARN
+
+# And this one to avoid the logs being spammed with KsqlConfig values.
+# Though these can be useful for debugging / investigations.
+#log4j.logger.io.confluent.ksql.util.KsqlConfig=WARN
+
+## Kafka Streams logs:
+log4j.logger.org.apache.kafka.streams=INFO, streams
+log4j.additivity.org.apache.kafka.streams=false
+
+## Kafka Client logs:
+log4j.logger.kafka=WARN, stdout
+log4j.logger.org.apache.zookeeper=WARN, stdout
+log4j.logger.org.apache.kafka=WARN, stdout
+log4j.logger.org.I0Itec.zkclient=WARN, stdout