External checkpoints to S3 on EMR

问题

I am trying to deploy a production cluster for my Flink program. I am using a standard hadoop-core EMR cluster with Flink 1.3.2 installed, using YARN to run it.

I am trying to configure my RocksDB to write my checkpoints to an S3 bucket. I am trying to go through these docs: https://ci.apache.org/projects/flink/flink-docs-release-1.3/setup/aws.html#set-s3-filesystem. The problem seems to be getting the dependencies working correctly. I receive this error when trying run the program:

java.lang.NoSuchMethodError: org.apache.hadoop.conf.Configuration.addResource(Lorg/apache/hadoop/conf/Configuration;)V
    at com.amazon.ws.emr.hadoop.fs.EmrFileSystem.initialize(EmrFileSystem.java:93)
    at org.apache.flink.runtime.fs.hdfs.HadoopFileSystem.initialize(HadoopFileSystem.java:328)
    at org.apache.flink.core.fs.FileSystem.getUnguardedFileSystem(FileSystem.java:350)
    at org.apache.flink.core.fs.FileSystem.get(FileSystem.java:389)
    at org.apache.flink.core.fs.Path.getFileSystem(Path.java:293)
    at org.apache.flink.runtime.state.filesystem.FsCheckpointStreamFactory.<init>(FsCheckpointStreamFactory.java:99)
    at org.apache.flink.runtime.state.filesystem.FsStateBackend.createStreamFactory(FsStateBackend.java:282)
    at org.apache.flink.contrib.streaming.state.RocksDBStateBackend.createStreamFactory(RocksDBStateBackend.java:273

I have tried both leaving and adjusting the core-site.xml and leaving it as is. I have tried setting the HADOOP_CLASSPATH to the /usr/lib/hadoop/share that contains(what I assume are) most of the JARs described in the above guide. I tried downloading the hadoop 2.7.2 binaries, and copying over them into the flink/libs directory. All resulting in the same error.

Has anyone successfully gotten Flink being able to write to S3 on EMR?

EDIT: My cluster setup

AWS Portal:

1) EMR -> Create Cluster
2) Advanced Options
3) Release = emr-5.8.0
4) Only select Hadoop 2.7.3
5) Next -> Next -> Next -> Create Cluster ( I do fill out names/keys/etc)

Once the cluster is up I ssh into the Master and do the following:

1  wget http://apache.claz.org/flink/flink-1.3.2/flink-1.3.2-bin-hadoop27-scala_2.11.tgz
2  tar -xzf flink-1.3.2-bin-hadoop27-scala_2.11.tgz
3  cd flink-1.3.2
4  ./bin/yarn-session.sh -n 2 -tm 5120 -s 4 -d
5  Change conf/flink-conf.yaml 
6  ./bin/flink run -m yarn-cluster -yn 1 ~/flink-consumer.jar

My conf/flink-conf.yaml I add the following fields:

state.backend: rocksdb
state.backend.fs.checkpointdir: s3:/bucket/location
state.checkpoints.dir: s3:/bucket/location

My program's checkpointing setup:

env.enableCheckpointing(getCheckpointRate,CheckpointingMode.EXACTLY_ONCE)
env.getCheckpointConfig.enableExternalizedCheckpoints(ExternalizedCheckpointCleanup.RETAIN_ON_CANCELLATION)
env.getCheckpointConfig.setMinPauseBetweenCheckpoints(getCheckpointMinPause)
env.getCheckpointConfig.setCheckpointTimeout(getCheckpointTimeout)
env.getCheckpointConfig.setMaxConcurrentCheckpoints(1)
env.setStateBackend(new RocksDBStateBackend("s3://bucket/location", true))

If there are any steps you think I am missing, please let me know

回答1:

I assume that you installed Flink 1.3.2 on your own on the EMR Yarn cluster, because Amazon does not yet offer Flink 1.3.2, right?

Given that, it seems as if you have a dependency conflict. The method org.apache.hadoop.conf.Configuration.addResource(Lorg/apache/hadoop/conf/Configuration) was only introduced with Hadoop 2.4.0. Therefore I assume that you have deployed a Flink 1.3.2 version which was built with Hadoop 2.3.0. Please deploy a Flink version which was built with the Hadoop version running on EMR. This will most likely solve all dependency conflicts.

Putting the Hadoop dependencies into the lib folder seems to not reliably work because the flink-shaded-hadoop2-uber.jar appears to have precedence in the classpath.

来源：https://stackoverflow.com/questions/46157946/external-checkpoints-to-s3-on-emr

标签

amazon-s3

apache-flink

emr

amazon-emr

rocksdb