Apache Flink to use S3 for backend state and checkpoints

Question

Background

• I was planning to use S3 to store the Flink's checkpoints using the FsStateBackend. But somehow I was getting the following error.

Error

org.apache.flink.core.fs.UnsupportedFileSystemSchemeException: Could not find a file system implementation for scheme 's3'. The scheme is not directly supported by Flink and no Hadoop file system to support this scheme could be loaded.

Flink version: I am using Flink 1.10.0 version.

Answer 1

I have found the solution for the above issue, so here I am listing it in steps that are required.

Steps

1. We need to add some configs in the flink-conf.yaml file which I have listed below.

state.backend: filesystem
state.checkpoints.dir: s3://s3-bucket/checkpoints/ #"s3://<your-bucket>/<endpoint>"
state.backend.fs.checkpointdir: s3://s3-bucket/checkpoints/ #"s3://<your-bucket>/<endpoint>"


s3.access-key: XXXXXXXXXXXXXXXXXXX #your-access-key
s3.secret-key: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx #your-secret-key

s3.endpoint: http://127.0.0.1:9000 #your-endpoint-hostname (I have used Minio) 

2. After completing the first step we need to copy the respective(flink-s3-fs-hadoop-1.10.0.jar and flink-s3-fs-presto-1.10.0.jar) JAR files from the opt directory to the plugins directory of your Flink.

   • E.g:--> 1. Copy /flink-1.10.0/opt/flink-s3-fs-hadoop-1.10.0.jar to /flink-1.10.0/plugins/s3-fs-hadoop/flink-s3-fs-hadoop-1.10.0.jar // Recommended for StreamingFileSink
     2. Copy /flink-1.10.0/opt/flink-s3-fs-presto-1.10.0.jar to /flink-1.10.0/plugins/s3-fs-presto/flink-s3-fs-presto-1.10.0.jar //Recommended for checkpointing

3. Add this in checkpointing code

env.setStateBackend(new FsStateBackend("s3://s3-bucket/checkpoints/"))

4. After completing all the above steps re-start the Flink if it is already running.

Note:

• If you are using both(flink-s3-fs-hadoop and flink-s3-fs-presto) in Flink then please use s3p:// specificly for flink-s3-fs-presto and s3a:// for flink-s3-fs-hadoop instead of s3://.
• For more details click here.