Flink on k8s容器日志生成原理及与Yarn部署时的日志生成模式对比

Flink on k8s部署日志详解及与Yarn部署时的日志生成模式对比

最近需要将flink由原先部署到Yarn集群切换到kubernetes集群，在切换之后需要熟悉flink on k8s的运行模式。在使用过程中针对日志模块发现，在k8s的容器中，flink的系统日志只有jobmanager.log/taskmanager.log 两个，而当时在使用Yarn集群部署时，flink的日志会有多个，比如:jobmanager.log、jobmanager.err和jobmanager.out，TaskManager同理。

因此，有同事就提出为什么在k8s中部署时，只有.log一个文件，能不能类似Yarn部署时那样对日志文件进行区分。只是从容器日志来看的话，在一开始不够了解k8s的情况下，会觉得日志收集的不够准确。

因此针对上面的这个问题，就归我进行研究和解决了。网上的相关资料也比较少，因此，在本次对上面这个问题整体了解分析之后，进行一次学习记录。有遇到相关类似问题的，也可以参考这个思路。

一、认为需要修改log4j配置即可

拿到这个问题的第一步首先想到的是，既然要对日志的类别进行区分，则可以修改log4j的配置，将INFO类别和ERROR类别分别写入不同的日志文件即可。于是，先对flink路径下的conf/log4j-console.properties进行修改(flink on k8s部署时，使用的log4j配置文件是flink-console.properties文件，而不是log4j.properties)。

这里我们留下一个小疑问：为什么部署到k8s中时，使用的是log4j-console.properties，而不是部署到Yarn时的log4j.properties？有什么区别？

修改后的log4j-console.properties示例如下所示：

################################################################################
#  Licensed to the Apache Software Foundation (ASF) under one
#  or more contributor license agreements.  See the NOTICE file
#  distributed with this work for additional information
#  regarding copyright ownership.  The ASF licenses this file
#  to you under the Apache License, Version 2.0 (the
#  "License"); you may not use this file except in compliance
#  with the License.  You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
# limitations under the License.
################################################################################

# Allows this configuration to be modified at runtime. The file will be checked every 30 seconds.
monitorInterval=30

# This affects logging for both user code and Flink
rootLogger.level = INFO
rootLogger.appenderRef.console.ref = ConsoleAppender
rootLogger.appenderRef.rolling.ref = RollingFileAppender
rootLogger.appenderRef.errorLogFile.ref = errorLogFile

# Uncomment this if you want to _only_ change Flink's logging
#logger.flink.name = org.apache.flink
#logger.flink.level = INFO

# The following lines keep the log level of common libraries/connectors on
# log level INFO. The root logger does not override this. You have to manually
# change the log levels here.
logger.akka.name = akka
logger.akka.level = INFO
logger.kafka.name= org.apache.kafka
logger.kafka.level = INFO
logger.hadoop.name = org.apache.hadoop
logger.hadoop.level = INFO
logger.zookeeper.name = org.apache.zookeeper
logger.zookeeper.level = INFO

# Log all infos to the console
appender.console.name = ConsoleAppender
appender.console.type = CONSOLE
appender.console.layout.type = PatternLayout
appender.console.layout.pattern = %d{yyyy-MM-dd HH:mm:ss,SSS} %-5p %-60c %x - %m%n

# Log all infos in the given rolling file
appender.rolling.name = RollingFileAppender
appender.rolling.type = RollingFile
appender.rolling.append = true
appender.rolling.fileName = ${sys:log.file}
appender.rolling.filePattern = ${sys:log.file}.%i
appender.rolling.layout.type = PatternLayout
appender.rolling.layout.pattern = %d{yyyy-MM-dd HH:mm:ss,SSS} %-5p %-60c %x - %m%n
appender.rolling.policies.type = Policies
appender.rolling.policies.size.type = SizeBasedTriggeringPolicy
appender.rolling.poli