[FLINK-11487] Support for writing data to Apache Flume

[ambition119]

What is the purpose of the change

This pull request corresponds to a FLINK-11487
Support for writing data to Apache Flume.

Brief change log

• flink-connectors add flink-connector-flume module
• org.apache.flink.streaming.connectors.flume.FlumeSink java
• FlumeSink example

Verifying this change

(Please pick either of the following options)

This change is a trivial rework / code cleanup without any test coverage.

(or)

This change is already covered by existing tests, such as (please describe tests).

(or)

This change added tests and can be verified as follows:

(example:)

• Added integration tests for end-to-end deployment with large payloads (100MB)
• Extended integration test for recovery after master (JobManager) failure
• Added test that validates that TaskInfo is transferred only once across recoveries
• Manually verified the change by running a 4 node cluser with 2 JobManagers and 4 TaskManagers, a stateful streaming program, and killing one JobManager and two TaskManagers during the execution, verifying that recovery happens correctly.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (yes / no)
• The serializers: (yes / no / don't know)
• The runtime per-record code paths (performance sensitive): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: (yes / no / don't know)
• The S3 file system connector: (yes / no / don't know)

Documentation

• Does this pull request introduce a new feature? (yes / no)

• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)

• Currently only examples of use are provided

[dawidwys]

Hi @ambition119, thank you for your interest to Flink project.

Could you please update PR description. Also I think we will need some more information about the design of the connector, supported feature set etc. This will help to properly review this contribution. Also you may want to have a look here what do we look for while reviewing. Thanks.

[sjwiesman]

Not sure if you are aware but there is already a flink connector for flume in Apache Bahir[1]. It might make more sense to consolidate your efforts with the work that’s already been done there or first discuss with the community if you think it makes more sense for this to be in Flink proper.

[1] https://github.com/apache/bahir-flink/tree/master/flink-connector-flume

[ambition119]

@sjwiesman Thank you for your comment, let me know Apache Bahir. At first I thought that the code I wrote was not very good, but after reading the code of Apache Bahir, I found my write code is very good.

@dawidwys I followed the history and found that it was moved from Flink to Bahir, so I will PR to Bahir again.