Try to get meaningful metrics from Zookeeper

[solsson]

Help wanted in order to improve #49. I can get JVM stats, but nothing org.apache.ZooKeeperService.

[yacut]

I thinks, the "Leader" and "Follower" labels are very useful for the zookeeper metrics:

lowercaseOutputName: true
jmxUrl: service:jmx:rmi:///jndi/rmi://localhost:5555/jmxrmi
ssl: false
whitelistObjectNames: ["org.apache.ZooKeeperService:*","java.lang:*"]
rules:
  - pattern: "org.apache.ZooKeeperService<name0=ReplicatedServer_id(\\d)><>(\\w+)"
    name: "zookeeper_$2"
  - pattern: "org.apache.ZooKeeperService<name0=ReplicatedServer_id(\\d), name1=replica.(\\d)><>(\\w+)"
    name: "zookeeper_$3"
    labels:
      replicaId: "$2"
  - pattern: "org.apache.ZooKeeperService<name0=ReplicatedServer_id(\\d), name1=replica.(\\d), name2=(\\w+)><>(\\w+)"
    name: "zookeeper_$4"
    labels:
      replicaId: "$2"
      memberType: "$3"
  - pattern: "org.apache.ZooKeeperService<name0=ReplicatedServer_id(\\d), name1=replica.(\\d), name2=(\\w+), name3=(\\w+)><>(\\w+)"
    name: "zookeeper_$4_$5"
    labels:
      replicaId: "$2"
      memberType: "$3"
  - pattern : java.lang<type=OperatingSystem><>SystemCpuLoad
  - pattern : java.lang<type=Memory><HeapMemoryUsage>used
  - pattern : java.lang<type=OperatingSystem><>FreePhysicalMemorySize

e.g. the metric rate(zookeeper_packetssent[1m]) shows the memberType and replicaId labels.

[solsson]

Thanks @yacut. I'm merging this to #49 as zoo's metrics are now on par with kafka's.