我们正在使用：
root@server:~# /usr/share/logstash/bin/logstash --version
logstash 6.2.4
在：
root@server:~# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.4 LTS
Release: 16.04
Codename: xenial
采用以下log4j2.properties配置：
status = error
name = LogstashPropertiesConfig
appender.rolling.type = RollingFile
appender.rolling.name = plain_rolling
appender.rolling.fileName = ${sys:ls.logs}/logstash-${sys:ls.log.format}.log
appender.rolling.filePattern = ${sys:ls.logs}/logstash-${sys:ls.log.format}-%d{yyyy-MM-dd}.log.gz
appender.rolling.policies.type = Policies
appender.rolling.policies.time.type = TimeBasedTriggeringPolicy
appender.rolling.policies.time.interval = 1
appender.rolling.policies.time.modulate = true
appender.rolling.strategy.type = DefaultRolloverStrategy
appender.rolling.strategy.action.type = Delete
appender.rolling.strategy.action.basePath = ${sys:ls.logs}
appender.rolling.strategy.action.condition.type = IfLastModified
appender.rolling.strategy.action.condition.age = 7D
appender.rolling.strategy.action.pathConditions.type = IfFileName
appender.rolling.strategy.action.pathConditions.glob = logstash-${sys:ls.log.format}-*
appender.rolling.layout.type = PatternLayout
appender.rolling.layout.pattern = [%d{ISO8601}][%-5p][%-25c] %-.10000m%n
appender.json_rolling.type = RollingFile
appender.json_rolling.name = json_rolling
appender.json_rolling.fileName = ${sys:ls.logs}/logstash-${sys:ls.log.format}.log
appender.json_rolling.filePattern = ${sys:ls.logs}/logstash-${sys:ls.log.format}-%d{yyyy-MM-dd}.log
appender.json_rolling.policies.type = Policies
appender.json_rolling.policies.time.type = TimeBasedTriggeringPolicy
appender.json_rolling.policies.time.interval = 1
appender.json_rolling.policies.time.modulate = true
appender.json_rolling.layout.type = JSONLayout
appender.json_rolling.layout.compact = true
appender.json_rolling.layout.eventEol = true
rootLogger.level = ${sys:ls.log.level}
rootLogger.appenderRef.rolling.ref = ${sys:ls.log.format}_rolling
根据Apache Log4j 2 文档为了RollingFileAppender：
如果文件模式以“.gz”、“.zip”、“.bz2”、“.deflate”、“.pack200”或“.xz”结尾，则生成的档案将使用与后缀匹配的压缩方案进行压缩。
我们已设定目标filePattern：
${sys:ls.logs}/logstash-${sys:ls.log.format}-%d{yyyy-MM-dd}.log.gz
但发现滚动的日志标有.gz扩展名，但实际上并未压缩，例如：
root@server:~# file /var/log/logstash/logstash-plain-2019-01-17.log.gz
/var/log/logstash/logstash-plain-2019-01-17.log.gz: ASCII text
我们已经gzip安装好了。我们还遗漏了什么？任何帮助都将不胜感激。