Adds mirrormaker example for GKE clusters

[solsson]

Tested with the default #78 in GKE.

A couple of manifest values need customization:

• WHITELIST
• GROUP_ID
• ip:s in source-endpoints.yml

Keeping resource limits low in order to reduce performance implications.

[solsson]

Does anyone know if there's a DNS name for a GKE cluster's nodes? That would solve bootstrap without dependence on ephemeral IP addresses.

[solsson]

Instead of having offset reset earliest which could lead to duplication, I think it makes sense to explicitly grant mirroring as triggered by the following error

[2018-05-01 17:16:47,351] ERROR [mirrormaker-thread-0] Mirror maker thread failure due to  (kafka.tools.MirrorMaker$MirrorMakerThread)
org.apache.kafka.clients.consumer.NoOffsetForPartitionException: Undefined offset with no reset policy for partitions: [ite-leanconstruction.yolean-live3.operations.001-0]
	at org.apache.kafka.clients.consumer.internals.SubscriptionState.resetMissingPositions(SubscriptionState.java:374)
	at org.apache.kafka.clients.consumer.KafkaConsumer.updateFetchPositions(KafkaConsumer.java:1794)
	at org.apache.kafka.clients.consumer.KafkaConsumer.pollOnce(KafkaConsumer.java:1152)
	at org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:1115)
	at kafka.tools.MirrorMaker$MirrorMakerNewConsumer.receive(MirrorMaker.scala:641)
	at kafka.tools.MirrorMaker$MirrorMakerThread.run(MirrorMaker.scala:428)
[2018-05-01 17:16:48,049] ERROR [mirrormaker-thread-0] Mirror maker thread exited abnormally, stopping the whole mirror maker. (kafka.tools.MirrorMaker$MirrorMakerThread)

The problem is that a new topic matching the whitelist would halt all other mirroring. I guess a group offset 0 could be set using kafkacat etc, but I have no strategy for not interrupting the mirroring of existing topics.

[solsson]

Use MM2