add redis channel

[JunLuo]

In some cases, we need events can not be lost. But we don't want to install zk & kafka. To make event deliver only once and to deploy many flume agents in different nodes but share only one channel, we developed redis channel. We already use the redis channel in out production environment, and we want to feed back to flume.

[bessbd]

Hi @JunLuo ,

Thanks for the pull request!

This looks like a very useful change to me. However, Travis CI has reported a compilation error:

[ERROR] COMPILATION ERROR : [INFO] ------------------------------------------------------------- [ERROR] /home/travis/build/apache/flume/flume-ng-channels/flume-redis-channel/src/test/java/org/flume/redis/channel/AppTest.java:[3,22] error: package junit.framework does not exist [ERROR] /home/travis/build/apache/flume/flume-ng-channels/flume-redis-channel/src/test/java/org/flume/redis/channel/AppTest.java:[4,22] error: package junit.framework does not exist [ERROR] /home/travis/build/apache/flume/flume-ng-channels/flume-redis-channel/src/test/java/org/flume/redis/channel/AppTest.java:[5,22] error: package junit.framework does not exist [ERROR] /home/travis/build/apache/flume/flume-ng-channels/flume-redis-channel/src/test/java/org/flume/redis/channel/AppTest.java:[11,12] error: cannot find symbol [ERROR] class TestCase /home/travis/build/apache/flume/flume-ng-channels/flume-redis-channel/src/test/java/org/flume/redis/channel/AppTest.java:[26,18] error: cannot find symbol [ERROR] class AppTest /home/travis/build/apache/flume/flume-ng-channels/flume-redis-channel/src/test/java/org/flume/redis/channel/AppTest.java:[28,19] error: cannot find symbol [ERROR] class AppTest /home/travis/build/apache/flume/flume-ng-channels/flume-redis-channel/src/test/java/org/flume/redis/channel/AppTest.java:[36,8] error: cannot find symbol [INFO] 7 errors

Can you please fix it, so that we can proceed with the reviews?

Thank you,

Donat

[JunLuo]

Hi @bessbd , I have fixed the errors about Junit and code style :)

[bessbd]

Hi @JunLuo ,

Thank you for the changes!

On a first pass, I've noticed that a new user guide entry is missing. For this change to get merged, some documentation would be necessary. For an example, I'd recommend Kafka Channel. Do you think you can make the necessary additions?

Thank you,

Donat

[JunLuo]

Hi @bessbd , I've add some documentation about redis channel :)

[JunLuo]

Hi @szaboferee , I've done these changes:

1. Add cluster and sentinel mode
2. Remove useless optional
3. Add the documention about cluster and sentinel
4. Move redis config to flume configuration
5. Fix the error of singleton
6. Add unit test

[JunLuo]

Hi @szaboferee ， I've fix all problems you mentions in commits, What should I do next?

[bessbd]

Overall, this change looks fine to me. After receiving feedback for the comments I have left, I'd like to request contributors and committers to do a review of this PR so that we can merge it.

[JunLuo]

Hi @bessbd , I've fix all problems you mentions in commits. :)

[asfgit]

Can one of the admins verify this patch?