因为在生产环境上需要上线一套ELK环境，但是日志收集程序Logstash需要依赖对应版本的JDK环境，具体的版本依赖在下载时有提示，提示如下：
https://www.elastic.co/downloads/logstash
Version: 6.1.3 Release date: January 30, 2018 Notes: View detailed release notes. Not the version you're looking for? View past releases.Java 8 is required for Logstash 6.x and 5.x. 可以看出需要依赖Java 8的环境。但是在生产系统中，已经部署好jdk1.7环境，而且无法轻易更改，如果不配置Java 8,会启动失败，报错信息如下： [root@server17 bin]# /opt/logstash-5.2.0/bin/logstash -e LoadError: JRuby ext built for wrong Java version in `com.purbon.jrmonitor.JRMonitorService': java.lang.UnsupportedClassVersionError: com/purbon/jrmonitor/JRMonitorService : Unsupported major.minor version 52.0 require at org/jruby/RubyKernel.java:1040 (root) at /opt/logstash-5.2.0/vendor/bundle/jruby/1.9/gems/jrmonitor-0.4.2/lib/jrmonitor.rb:4 require at org/jruby/RubyKernel.java:1040 (root) at /opt/logstash-5.2.0/logstash-core/lib/logstash/instrument/periodic_poller/jvm.rb:1 require at org/jruby/RubyKernel.java:1040 (root) at /opt/logstash-5.2.0/logstash-core/lib/logstash/instrument/periodic_poller/jvm.rb:5 require at org/jruby/RubyKernel.java:1040 (root) at /opt/logstash-5.2.0/logstash-core/lib/logstash/instrument/periodic_pollers.rb:1 require at org/jruby/RubyKernel.java:1040 (root) at /opt/logstash-5.2.0/logstash-core/lib/logstash/instrument/periodic_pollers.rb:3 require at org/jruby/RubyKernel.java:1040 (root) at /opt/logstash-5.2.0/lib/bootstrap/environment.rb:70 因此需要对Logstash配置单独的Java环境，只需要分别在如下两个配置文件里面配置Java环境即可： export JAVA_HOME=/usr/local/jdk1.8 1、~/logstash-5.2.0/bin/logstash 2、~/logstash-5.2.0/bin/logstash.lib.sh