Standalone模式下，通过Systemd管理Flink1.11.1的启停及异常退出
Flink以Standalone模式运行时，可能会发生jobmanager（以下简称jm）或taskmanager（以下简称tm）异常退出的情况，我们可以使用Linux自带的Systemd方式管理jm以及tm的启停，并在jm或tm出现故障时，及时将jm以及tm拉起来。
Flink在1.11版本后，从发行版中移除了对Hadoop的依赖包，如果需要使用Hadoop的一些特性，有两种解决方案：
【注】以下假设java、flink、hadoop都安装在/opt目录下，并且都建立了软连接：
1.设置HADOOP_CLASSPATH环境变量（推荐方案）
在安装了Flink的所有节点上，在/etc/profile中进行如下设置：
# Hadoop Env
export HADOOP_HOME=/opt/hadoop
export PATH=$PATH:$HADOOP_HOME/bin:$HADOOP_HOME/sbin
export HADOOP_CLASSPATH=`hadoop classpath`
然后通过以下命令使环境变量生效
sudo source /etc/profile
2.下载flink-shaded-hadoop-2-uber对应的jar包，并拷贝到Flink安装路径的lib目录下
下载地址：//flink.apache.org/downloads.html#additional-components
由于以systemd方式启动时，系统设置的环境变量，在.service文件中是不能使用的，所以需要在.service文件中单独显式设置环境变量：
1./usr/lib/systemd/system/flink-jobmanager.service
[Unit] Description=Flink Job Manager After=syslog.target network.target remote-fs.target nss-lookup.target network-online.target Requires=network-online.target [Service] User=teld Group=teld Type=forking Environment=PATH=/opt/java/bin:/opt/flink/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin Environment=JAVA_HOME=/opt/java Environment=FLINK_HOME=/opt/flink Environment=HADOOP_CLASSPATH=/opt/hadoop/etc/hadoop:/opt/hadoop/share/hadoop/common/lib/*:/opt/hadoop/share/hadoop/common/*:/opt/hadoop/ share/hadoop/hdfs:/opt/hadoop/share/hadoop/hdfs/lib/*:/opt/hadoop/share/hadoop/hdfs/*:/opt/hadoop/share/hadoop/yarn/lib/*:/opt/hadoop/sh are/hadoop/yarn/*:/opt/hadoop/share/hadoop/mapreduce/lib/*:/opt/hadoop/share/hadoop/mapreduce/*:/opt/hadoop/contrib/capacity-scheduler/* .jar ExecStart=/opt/flink/bin/jobmanager.sh start ExecStop=/opt/flink/bin/jobmanager.sh stop Restart=on-failure [Install] WantedBy=multi-user.target
【注】HADOOP_CLASSPATH对应的值，是通过执行以下命令获得到的：
hadoop classpath
2./usr/lib/systemd/system/flink-taskmanager.service
[Unit] Description=Flink Task Manager After=syslog.target network.target remote-fs.target nss-lookup.target network-online.target Requires=network-online.target [Service] User=teld Group=teld Type=forking Environment=PATH=/opt/java/bin:/opt/flink/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin Environment=JAVA_HOME=/opt/java Environment=FLINK_HOME=/opt/flink Environment=HADOOP_CLASSPATH=/opt/hadoop/etc/hadoop:/opt/hadoop/share/hadoop/common/lib/*:/opt/hadoop/share/hadoop/common/*:/opt/hadoop/ share/hadoop/hdfs:/opt/hadoop/share/hadoop/hdfs/lib/*:/opt/hadoop/share/hadoop/hdfs/*:/opt/hadoop/share/hadoop/yarn/lib/*:/opt/hadoop/sh are/hadoop/yarn/*:/opt/hadoop/share/hadoop/mapreduce/lib/*:/opt/hadoop/share/hadoop/mapreduce/*:/opt/hadoop/contrib/capacity-scheduler/* .jar ExecStart=/opt/flink/bin/taskmanager.sh start ExecStop=/opt/flink/bin/taskmanager.sh stop Restart=on-failure [Install] WantedBy=multi-user.target
【注】HADOOP_CLASSPATH对应的值，是通过执行以下命令获得到的：
hadoop classpath
通过sudo systemctl daemon-reload命令来加载上面针对jm以及tm的配置后，就可以使用Systemd的方式来管理jm以及tm了，并且能够在jm以及tm异常退出时，及时将它们拉起来：
sudo systemctl start flink-jobmanager.service
sudo systemctl stop flink-jobmanager.service
sudo systemctl status flink-jobmanager.service
sudo systemctl start flink-taskmanager.service
sudo systemctl stop flink-taskmanager.service
sudo systemctl status flink-jobmanager.service
遇到的坑：
1.如果Flink设置了启用Checkpoint，但是没有设置HADOOP_CLASSPATH环境变量，则提交job的时候，会报如下异常：
Caused by: org.apache.flink.util.FlinkRuntimeException: Failed to create checkpoint storage at checkpoint coordinator side. at org.apache.flink.runtime.checkpoint.CheckpointCoordinator.<init>(CheckpointCoordinator.java:304) at org.apache.flink.runtime.checkpoint.CheckpointCoordinator.<init>(CheckpointCoordinator.java:223) at org.apache.flink.runtime.executiongraph.ExecutionGraph.enableCheckpointing(ExecutionGraph.java:483) at org.apache.flink.runtime.executiongraph.ExecutionGraphBuilder.buildGraph(ExecutionGraphBuilder.java:338) at org.apache.flink.runtime.scheduler.SchedulerBase.createExecutionGraph(SchedulerBase.java:269) at org.apache.flink.runtime.scheduler.SchedulerBase.createAndRestoreExecutionGraph(SchedulerBase.java:242) at org.apache.flink.runtime.scheduler.SchedulerBase.<init>(SchedulerBase.java:229) at org.apache.flink.runtime.scheduler.DefaultScheduler.<init>(DefaultScheduler.java:119) at org.apache.flink.runtime.scheduler.DefaultSchedulerFactory.createInstance(DefaultSchedulerFactory.java:103) at org.apache.flink.runtime.jobmaster.JobMaster.createScheduler(JobMaster.java:284) at org.apache.flink.runtime.jobmaster.JobMaster.<init>(JobMaster.java:272) at org.apache.flink.runtime.jobmaster.factories.DefaultJobMasterServiceFactory.createJobMasterService(DefaultJobMasterServiceFac tory.java:98) at org.apache.flink.runtime.jobmaster.factories.DefaultJobMasterServiceFactory.createJobMasterService(DefaultJobMasterServiceFac tory.java:40) at org.apache.flink.runtime.jobmaster.JobManagerRunnerImpl.<init>(JobManagerRunnerImpl.java:140) at org.apache.flink.runtime.dispatcher.DefaultJobManagerRunnerFactory.createJobManagerRunner(DefaultJobManagerRunnerFactory.java :84) at org.apache.flink.runtime.dispatcher.Dispatcher.lambda$createJobManagerRunner$6(Dispatcher.java:388) ... 7 more Caused by: org.apache.flink.core.fs.UnsupportedFileSystemSchemeException: Could not find a file system implementation for scheme 'hdfs'. The scheme is not directly supported by Flink and no Hadoop file system to support this scheme could be loaded. For a full list of supp
2.在为flink-jobmanager.service以及flink-taskmanager.service中的HADOOP_CLASSPATH环境变量赋值时，尝试使用过反引号，期望将反引号内的Linux命令执行结果赋予变量，但实际上并不会执行反引号中的内容：
Environment=HADOOP_CLASSPATH=`/opt/hadoop/bin/hadoop classpath`
最后只得将直接执行hadoop classpath获得的结果，粘贴到.service文件中
Environment=HADOOP_CLASSPATH=/opt/hadoop/etc/hadoop:/opt/hadoop/share/hadoop/common/lib/*:/opt/hadoop/share/hadoop/common/*:/opt/hadoop/ share/hadoop/hdfs:/opt/hadoop/share/hadoop/hdfs/lib/*:/opt/hadoop/share/hadoop/hdfs/*:/opt/hadoop/share/hadoop/yarn/lib/*:/opt/hadoop/sh are/hadoop/yarn/*:/opt/hadoop/share/hadoop/mapreduce/lib/*:/opt/hadoop/share/hadoop/mapreduce/*:/opt/hadoop/contrib/capacity-scheduler/* .jar
