Docker之Hadoop普通集群搭建
docker搭建下hadoop集群，分布式的搭建与伪分布式的并无多大区别，在伪分布式下，各种配置文件中对于ip或者主机名全都是一致的，而在分布式下只要需要把相应namenode、resourcemanager所在节点对应IP配置正确，在slaves中添加所有datanode节点ip或主机名即可。使用的镜像为hadoop-2.6.0-cdh5.4.5.tar.gz。
在docker之上搭建一个容器为master节点，并在之上运行namenode和resourcemanager节点，其余节点为slaves，运行datanode和nodemanager节点，配置的所有节点都使用同一样的配置文件，所以可以制作成一个docker镜像，然后用同一个镜像运行多个容器，电脑上容器的ip分配是从第一个容器开始就是172.17.0.2，往后创建的容器对应ip递增。所以配置文件中对应的namenode和resourcemanager的ip地址可以设置成172.17.0.2，其余容器ip写到slaves中。
详细的配置文件信息如下：
core-site.xml ：
fs.defaultFS
hdfs://172.17.0.2:9000
io.file.buffer.size
131072
hadoop.tmp.dir
file:/data/tmp
hdfs-site.xml：
dfs.namenode.name.dir
file:/data/hdfs/name
true
dfs.datanode.data.dir
file:/data/hdfs/data
dfs.replication
2
dfs.permissions
false
dfs.namenode.datanode.registration.ip-hostname-check
false
mapred-site.xml：
mapreduce.framework.name
yarn
yarn-site.xml：
yarn.nodemanager.aux-services
mapreduce_shuffle
yarn.resourcemanager.resource-tracker.address
172.17.0.2:8031
yarn.resourcemanager.address
172.17.0.2:8032
yarn.resourcemanager.scheduler.address
172.17.0.2:8034
yarn.resourcemanager.webapp.address
172.17.0.2:8088
slaves：
172.17.0.3
172.17.0.4
172.17.0.5
172.17.0.6
详细搭建步骤：
1、JDK安装
mkdir /usr/java
tar -zxvf jdk-7u79-linux-x64.tar.gz -C /usr/java把jdk包解压后，需要设置相关环境变量，但在docker下的环境变量配置与传统方法有所不大一样，可以参考我的上一遍《Docker镜像之Java环境搭建（四）》进行配置。
2、ssh免密码登录
#在用户当前工作路径下，直接输cd并回车进入
cd
mkdir .ssh
ssh-keygen -t rsa
cd .ssh
cp id_rsa.pub authorized_keys
cd
chmod 700 .ssh
chmod 600 .ssh/*3、hadoop安装
mkdir /var/hadoop
tar -zxvf hadoop-2.6.0-cdh5.4.5.tar.gz -C /var/hadoop
cd /var/hadoop
mv hadoop-2.6.0-cdh5.4.5/ hadoop-2.6.0
mkdir -p /data/hdfs/name
mkdir -p /data/hdfs/data
mkdir -p /data/tmp#环境变量设置，以下环境变量的配置，一般情况直接写入到.bashrc文件中，docker中的配置会有所不同
HADOOP_HOME=/var/hadoop/hadoop-2.6.0
PATH=$HADOOP_HOME/bin:$HADOOP_HOME/sbin:$PATH
export HADOOP_HOME PATH4、配置文件
直接把前面提到的core-site.xml等5个文件复制到$HADOOP_HOME/etc/hadoop目录下即可。
5、格式化namenode
hdfs namenode -format6、启动hadoop
在master节点（172.17.0.2）启动集群：
start-dfs.sh
start-yarn.sh
mr-jobhistory-daemon.sh start historyserver
jps7、测试
hdfs dfs -mkdir /wordcount
hdfs dfs -put wordcount.txt /wordcount/wordcount.txt
yarn jar /var/hadoop/hadoop-2.6.0/share/hadoop/mapreduce/hadoop-mapreduce-examples-2.6.0-cdh5.4.5.jar wordcount /wordcount/wordcount.txt /wordcount/output17/01/10 17:08:56 INFO mapreduce.Job: Running job: job_1484068103061_0001
17/01/10 17:09:04 INFO mapreduce.Job: Job job_1484068103061_0001 running in uber mode : false
17/01/10 17:09:04 INFO mapreduce.Job: map 0% reduce 0%
17/01/10 17:09:12 INFO mapreduce.Job: map 100% reduce 0%
17/01/10 17:09:19 INFO mapreduce.Job: map 100% reduce 100%
17/01/10 17:09:20 INFO mapreduce.Job: Job job_1484068103061_0001 completed successfully8、整个配置过程中遇到的问题
8.1、start-dfs.sh启动时很多datanode无法启动成功，多尝试几次，或十来次才可以启动成功，发现log错误如下：
2017-01-08 03:36:29,815 FATAL org.apache.hadoop.hdfs.server.datanode.DataNode: Exception in secureMain
java.net.UnknownHostException: 26b72653d296: 26b72653d296: unknown error
at java.net.InetAddress.getLocalHost(InetAddress.java:1505)
at org.apache.hadoop.security.SecurityUtil.getLocalHostName(SecurityUtil.java:187)
at org.apache.hadoop.security.SecurityUtil.login(SecurityUtil.java:207)
at org.apache.hadoop.hdfs.server.datanode.DataNode.instantiateDataNode(DataNode.java:2289)
at org.apache.hadoop.hdfs.server.datanode.DataNode.createDataNode(DataNode.java:2338)
at org.apache.hadoop.hdfs.server.datanode.DataNode.secureMain(DataNode.java:2515)
at org.apache.hadoop.hdfs.server.datanode.DataNode.main(DataNode.java:2539)
Caused by: java.net.UnknownHostException: 26b72653d296: unknown error
at java.net.Inet4AddressImpl.lookupAllHostAddr(Native Method)
at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:928)
at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1323)
at java.net.InetAddress.getLocalHost(InetAddress.java:1500)按日志来看，觉得应该是主机名解析有问题而出错，然后直接把slaves中原来保存的主机名全都换成ip地址，问题就可以解决了。
8.2、Start-dfs.sh启动datanode提示所有节点启动成功，但在50070网页上并未发现任何节点，日志发现如下错误：
2017-01-08 05:39:48,880 ERROR org.apache.hadoop.hdfs.server.datanode.DataNode: Initialization failed for Block pool BP-1803144284-192.168.1.1-1483792012201 (Datanode Uuid null) service to 172.17.0.2/172.17.0.2:9000 Datanode denied communication with namenode because hostname cannot be resolved (ip=172.17.0.3, hostname=172.17.0.3): DatanodeRegistration(0.0.0.0, datanodeUuid=c19b9c4d-0e64-43ba-b458-281ae1af4738, infoPort=50075, ipcPort=50020, storageInfo=lv=-56;cid=CID-40010481-40ed-4830-8547-27eabc5af90f;nsid=517203298;c=0)
at org.apache.hadoop.hdfs.server.blockmanagement.DatanodeManager.registerDatanode(DatanodeManager.java:904)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.registerDatanode(FSNamesystem.java:5088)
at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.registerDatanode(NameNodeRpcServer.java:1141)
at org.apache.hadoop.hdfs.protocolPB.DatanodeProtocolServerSideTranslatorPB.registerDatanode(DatanodeProtocolServerSideTranslatorPB.java:93)
at org.apache.hadoop.hdfs.protocol.proto.DatanodeProtocolProtos$DatanodeProtocolService$2.callBlockingMethod(DatanodeProtocolProtos.java:28293)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:619)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:1060)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2044)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2040)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1671)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2038)需要在hdfs-site.xml加上如下内容就可以解决：
dfs.namenode.datanode.registration.ip-hostname-check
false
8.3、不要多次调用hdfs namenode -format进行格式化namenode，中间遇到过一个问题，50070上只显示一个节点，每次刷新发现ip都会发生改变，相应log忘记保存，但最终把/data/hdfs/name、/data/hdfs/data、/data/tmp下的所以文件删除并重新格式化后，重新启动start-dfs.sh，50070上正常显示多节点。后续再格式化，再执行start-dfs.sh发现datanode无法正常启动，日志如下：
2017-01-08 11:27:03,961 FATAL org.apache.hadoop.hdfs.server.datanode.DataNode: Initialization failed for Block pool (Datanode Uuid unassigned) service to /172.17.0.2:9000. Exiting.
java.io.IOException: All specified directories are failed to load.
at org.apache.hadoop.hdfs.server.datanode.DataStorage.recoverTransitionRead(DataStorage.java:479)
at org.apache.hadoop.hdfs.server.datanode.DataNode.initStorage(DataNode.java:1398)
at org.apache.hadoop.hdfs.server.datanode.DataNode.initBlockPool(DataNode.java:1363)
at org.apache.hadoop.hdfs.server.datanode.BPOfferService.verifyAndSetNamespaceInfo(BPOfferService.java:317)
at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.connectToNNAndHandshake(BPServiceActor.java:228)
at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.run(BPServiceActor.java:845)
at java.lang.Thread.run(Thread.java:745) 8.4、运行wordcount用例报错
17/01/09 15:15:05 INFO mapreduce.Job: Job job_1483969899500_0004 failed with state FAILED due to: Ap
plication application_1483969899500_0004 failed 2 times due to Error launching appattempt_1483969899
500_0004_000002. Got exception: java.io.IOException: Failed on local exception: java.io.IOException:
Couldn't set up IO streams; Host Details : local host is: "6696a6544d4c/172.17.0.2"; destination ho
st is: "3e2a08477956":39523;
at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:772)
at org.apache.hadoop.ipc.Client.call(Client.java:1472)
at org.apache.hadoop.ipc.Client.call(Client.java:1399)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:232)
at com.sun.proxy.$Proxy32.startContainers(Unknown Source)
at org.apache.hadoop.yarn.api.impl.pb.client.ContainerManagementProtocolPBClientImpl.startCo
ntainers(ContainerManagementProtocolPBClientImpl.java:96)
at org.apache.hadoop.yarn.server.resourcemanager.amlauncher.AMLauncher.launch(AMLauncher.jav
a:119)
at org.apache.hadoop.yarn.server.resourcemanager.amlauncher.AMLauncher.run(AMLauncher.java:2
54)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.io.IOException: Couldn't set up IO streams
at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:786)
at org.apache.hadoop.ipc.Client$Connection.access$2800(Client.java:368)
at org.apache.hadoop.ipc.Client.getConnection(Client.java:1521)
at org.apache.hadoop.ipc.Client.call(Client.java:1438)
... 9 more
Caused by: java.nio.channels.UnresolvedAddressException
at sun.nio.ch.Net.checkAddress(Net.java:101)
at sun.nio.ch.SocketChannelImpl.connect(SocketChannelImpl.java:622)
at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:192)
at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:530)
at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:494)
at org.apache.hadoop.ipc.Client$Connection.setupConnection(Client.java:607)
at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:705)