在docker里面安裝hadoop HA 在啟動或者停止的時候報ssh不能解析問題。

問題現象：

發現圖片不清晰：把問題現象粘貼如下：

root@master:/usr/local/hadoop-2.9.1# start-dfs.sh
Starting namenodes on [2018-10-15 09:45:30,412 WARN [main] util.NativeCodeLoader (NativeCodeLoader.java:<clinit>(62)) - Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
master slave1]
[main]: ssh: Could not resolve hostname [main]: Name or service not known
(NativeCodeLoader.java:<clinit>(62)): ssh: Could not resolve hostname (nativecodeloader.java:<clinit>(62)): Name or service not known
WARN: ssh: Could not resolve hostname warn: Name or service not known
-: ssh: Could not resolve hostname -: Name or service not known
Unable: ssh: Could not resolve hostname unable: Name or service not known
load: ssh: Could not resolve hostname load: Name or service not known
native-hadoop: ssh: Could not resolve hostname native-hadoop: Name or service not known
for: ssh: Could not resolve hostname for: Name or service not known
2018-10-15: ssh: Could not resolve hostname 2018-10-15: Name or service not known
library: ssh: Could not resolve hostname library: Name or service not known
platform...: ssh: Could not resolve hostname platform...: Name or service not known
your: ssh: Could not resolve hostname your: Name or service not known
using: ssh: Could not resolve hostname using: Name or service not known
where: ssh: Could not resolve hostname where: Name or service not known
builtin-java: ssh: Could not resolve hostname builtin-java: Name or service not known
util.NativeCodeLoader: ssh: Could not resolve hostname util.nativecodeloader: Name or service not known
applicable: ssh: Could not resolve hostname applicable: Name or service not known
classes: ssh: Could not resolve hostname classes: Name or service not known
slave1: starting namenode, logging to /usr/local/hadoop-2.9.1/logs/hadoop-root-namenode-slave1.out
master: starting namenode, logging to /usr/local/hadoop-2.9.1/logs/hadoop-root-namenode-master.out
09:45:30,412: ssh: Could not resolve hostname 09:45:30,412: Name or service not known
to: ssh: Could not resolve hostname to: No address associated with hostname
slave2: starting datanode, logging to /usr/local/hadoop-2.9.1/logs/hadoop-root-datanode-slave2.out
slave1: starting datanode, logging to /usr/local/hadoop-2.9.1/logs/hadoop-root-datanode-slave1.out
Starting secondary namenodes [2018-10-15 09:45:43,878 WARN [main] util.NativeCodeLoader (NativeCodeLoader.java:<clinit>(62)) - Unable to load native-hadoop library for your platform... using builtin-java classes where applicable]
util.NativeCodeLoader: ssh: Could not resolve hostname util.nativecodeloader: Name or service not known
WARN: ssh: Could not resolve hostname warn: Name or service not known
[main]: ssh: Could not resolve hostname [main]: Name or service not known
2018-10-15: ssh: Could not resolve hostname 2018-10-15: Name or service not known
-: ssh: Could not resolve hostname -: Name or service not known
(NativeCodeLoader.java:<clinit>(62)): ssh: Could not resolve hostname (nativecodeloader.java:<clinit>(62)): Name or service not known
Unable: ssh: Could not resolve hostname unable: Name or service not known
09:45:43,878: ssh: Could not resolve hostname 09:45:43,878: Name or service not known
to: ssh: Could not resolve hostname to: No address associated with hostname
native-hadoop: ssh: Could not resolve hostname native-hadoop: Name or service not known
library: ssh: Could not resolve hostname library: Name or service not known
for: ssh: Could not resolve hostname for: Name or service not known
platform...: ssh: Could not resolve hostname platform...: Name or service not known
your: ssh: Could not resolve hostname your: Name or service not known
builtin-java: ssh: Could not resolve hostname builtin-java: Name or service not known
classes: ssh: Could not resolve hostname classes: Name or service not known
where: ssh: Could not resolve hostname where: Name or service not known
applicable: ssh: Could not resolve hostname applicable: Name or service not known
using: ssh: Could not resolve hostname using: Name or service not known
load: ssh: Could not resolve hostname load: Name or service not known

通過報錯現象分析，是由于ssh解析錯誤，但是我的/etc/hosts里面主機名與ip地址的映射關系完全沒問題，這個時候就不能是ssh問題，那就肯定是hadoop本身的問題。

查看上面的圖，看我紅框里面的信息，不難發現ssh把

Starting namenodes on [2018-10-15 09:45:30,412 WARN [main] util.NativeCodeLoader (NativeCodeLoader.java:<clinit>(62)) - Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
master slave1]

這條警告信息當做域名去解析了，所以肯定有問題。

解決辦法：

打開 hadoop路徑/etc/hadoop/log4j.properties 添加如下信息：

log4j.logger.org.apache.hadoop.util.NativeCodeLoader=ERROR
這條信息的作用就是在log4j里面去除警告，記住是添加。

網上解決其他辦法：（對于我這種情況不合適）

出現上述問題主要是環境變量沒設置好，在~/.bash_profile或者/etc/profile中加入以下語句就沒問題了。

　　#vi /etc/profile或者vi ~/.bash_profile
　　　　export HADOOP_COMMON_LIB_NATIVE_DIR=$HADOOP_HOME/lib/native
　　　　export HADOOP_OPTS="-Djava.library.path=$HADOOP_HOME/lib"，

有的答案說不能加這個雙引號：export HADOOP_OPTS=-Djava.library.path=$HADOOP_HOME/lib，但具體怎樣，我也不太清楚，因為這種方法沒有解決掉我問題。所以說很多問題雖然看似跟網上其他人的問題相似，但最終卻不能解決掉自己問題，在這種情況下還得自己好好分析，分析出錯的現象，說實話，我這個問題我也是花了不少時間才發現的，也是由于不細心以及太依賴于百度了。這里記錄一下，也是希望可以幫助到出現類似問題的小伙伴。

然后用source重新編譯使之生效即可！
　　#source /etc/profile或者source ~/.bash_profile

還有一種情況也會出現類似的警告問題，那就是版本不兼容。比如說你下載的hadoop版本是64位的，但你的系統是32位，或者相反，系統64位，hadoop32位。

查看hadoop版本：

進入到如下目錄：/usr/local/hadoop-2.9.1/lib/native（這是我的hadoop安裝目錄，具體情況看你自己安裝的目錄），

使用ldd或者file命令查看版本：centos系統查看

說明是64位的。

Ubuntu查看：

說明是64位。

file命令也可以查看：

同樣說明hadoop是64位。查看操作系統版本使用uname -a就可以。

解決辦法同樣是在log4j的文件里面加入

log4j.logger.org.apache.hadoop.util.NativeCodeLoader=ERROR



參考：https://blog.csdn.net/l1028386804/article/details/51538611

轉載于:https://www.cnblogs.com/yjt1993/p/9789761.html

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