Hey Matthias,
Maybe the classpath contains hadoop libraries, but not the HDFS libraries?
The "DistributedFileSystem" class needs to be accessible to the
classloader. Can you check if that class is available?
Best,
Robert
On Thu, Mar 25, 2021 at 11:10 AM Matthias Seiler <
matthias.sei...@campus.tu-berlin.de> wrote:
> Hello everybody,
>
> I set up a a Flink (1.12.1) and Hadoop (3.2.1) cluster on two machines.
> The job should store the checkpoints on HDFS like so:
> ```java
> StreamExecutionEnvironment env =
> StreamExecutionEnvironment.getExecutionEnvironment();
> env.enableCheckpointing(15000, CheckpointingMode.EXACTLY_ONCE);
> env.setStateBackend(new FsStateBackend("hdfs://node-1:9000/flink"));
> ```
>
> Unfortunately, the JobManager throws
> ```
> 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 supported file systems,
> please see
> https://ci.apache.org/projects/flink/flink-docs-stable/ops/filesystems/.
> // ...
> Caused by:
> org.apache.flink.core.fs.UnsupportedFileSystemSchemeException: Hadoop is
> not in the classpath/dependencies.
> ```
> and I don't understand why.
>
> `echo $HADOOP_CLASSPATH` returns the path of Hadoop libraries with
> wildcards. Flink's JobManger prints the classpath which includes
> specific packages from these Hadoop libraries. Besides that, Flink
> creates the state directories on HDFS, but no content.
>
> Thank you for any advice,
> Matthias
>
>
