解决linux下root运行Elasticsearch异常

在CentOS 6.5 上运行Elasticsearch 2.3,异常如下：

Exception in thread "main" java.lang.RuntimeException: don't run elasticsearch as root.
         at org.elasticsearch.bootstrap.Bootstrap.initializeNatives(Bootstrap.java:93)
        at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:144)
        at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:270)
        at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:35)
Refer to the log for complete error details.

异常描述为不能以root权限运行Elasticsearch.解决办法是运行时加上参数：

bin/elasticsearch -Des.insecure.allow.root=true

或者修改bin/elasticsearch，加上ES_JAVA_OPTS属性：

ES_JAVA_OPTS="-Des.insecure.allow.root=true"

保存之后重启Elasticsearch。