elasticsearch 启动时，指定jdk的版本

环境

服务器：centos6
操作系统：win7
工具：CRT
elasticsearch：6.0.0

场景

拿我公司举例，我公司目前都是使用jdk1.7，并且线上已经有很多程序在跑啦！所以通过修改环境的方式，肯定是不行，而启动elasticsearch.6.0，有需要jdk8

修改启动脚本

这种情况下，我们就需要在启动elasticsearch时，就需要指定jdk版本。
即修改elasticsearch的启动脚本（elasticsearch_HOME/bin/elasticsearch）

[root@master01 elasticsearch-6.0.0]# vim bin/elasticsearch
# 添加以下代码
export JAVA_HOME=/home/yutao/jdk1.8.0_121/
export PATH=$JAVA_HOME/bin:$PATH

if [ -x "$JAVA_HOME/bin/java" ]; then
        JAVA="/home/yutao/jdk1.8.0_121/bin/java"
else
        JAVA=`which java`
fi

这里我也给我完整的文件：

#!/bin/bash

# CONTROLLING STARTUP:
#
# This script relies on a few environment variables to determine startup
# behavior, those variables are:
#
#   ES_PATH_CONF -- Path to config directory
#   ES_JAVA_OPTS -- External Java Opts on top of the defaults set
#
# Optionally, exact memory values can be set using the `ES_JAVA_OPTS`. Note that
# the Xms and Xmx lines in the JVM options file must be commented out. Example
# values are "512m", and "10g".
#
#   ES_JAVA_OPTS="-Xms8g -Xmx8g" ./bin/elasticsearch
# 我添加的 start
export JAVA_HOME=/home/yutao/jdk1.8.0_121/
export PATH=$JAVA_HOME/bin:$PATH
# 我添加的 end
source "`dirname "$0"`"/elasticsearch-env

parse_jvm_options() {
  if [ -f "$1" ]; then
    echo "`grep "^-" "$1" | tr '\n' ' '`"
  fi
}

ES_JVM_OPTIONS="$ES_PATH_CONF"/jvm.options

ES_JAVA_OPTS="`parse_jvm_options "$ES_JVM_OPTIONS"` $ES_JAVA_OPTS"

# 我添加的 start
if [ -x "$JAVA_HOME/bin/java" ]; then
        JAVA="/home/yutao/jdk1.8.0_121/bin/java"
else
        JAVA=`which java`
fi
# 我添加的 end

# manual parsing to find out, if process should be detached
if ! echo $* | grep -E '(^-d |-d$| -d |--daemonize$|--daemonize )' > /dev/null; then
  exec \
    "$JAVA" \
    $ES_JAVA_OPTS \
    -Des.path.home="$ES_HOME" \
    -Des.path.conf="$ES_PATH_CONF" \
    -cp "$ES_CLASSPATH" \
    org.elasticsearch.bootstrap.Elasticsearch \
    "$@"
else
  exec \
    "$JAVA" \
    $ES_JAVA_OPTS \
    -Des.path.home="$ES_HOME" \
    -Des.path.conf="$ES_PATH_CONF" \
    -cp "$ES_CLASSPATH" \
    org.elasticsearch.bootstrap.Elasticsearch \
    "$@" \
    <&- &
  retval=$?
  pid=$!
  [ $retval -eq 0 ] || exit $retval
  if [ ! -z "$ES_STARTUP_SLEEP_TIME" ]; then
    sleep $ES_STARTUP_SLEEP_TIME
  fi
  if ! ps -p $pid > /dev/null ; then
    exit 1
  fi
  exit 0
fi

exit $?

这样就修改完毕；

启动时，不要用root用户，被官方禁止啦！会报错的！

还有我发现，有时修改明明对了，启动时，还是报：

[yutao@master01 elasticsearch-6.0.0]# bin/elasticsearch
the minimum required Java version is 8; your Java version from [/usr/java/jdk1.7.0_51/jre] does not meet this requirement

有时又正常啦，不明白！

参考地址：

http://blog.youkuaiyun.com/liubenlong007/article/details/54708107