3 This helm chart provides an implementation of the ZooKeeper [StatefulSet](http://kubernetes.io/docs/concepts/abstractions/controllers/statefulsets/) found in Kubernetes Contrib [Zookeeper StatefulSet](https://github.com/kubernetes/contrib/tree/master/statefulsets/zookeeper).
7 * PersistentVolume support on the underlying infrastructure
8 * A dynamic provisioner for the PersistentVolumes
9 * A familiarity with [Apache ZooKeeper 3.4.x](https://zookeeper.apache.org/doc/current/)
12 This chart will do the following:
14 * Create a fixed size ZooKeeper ensemble using a [StatefulSet](http://kubernetes.io/docs/concepts/abstractions/controllers/statefulsets/).
15 * Create a [PodDisruptionBudget](https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-disruption-budget/) so kubectl drain will respect the Quorum size of the ensemble.
16 * Create a [Headless Service](https://kubernetes.io/docs/concepts/services-networking/service/) to control the domain of the ZooKeeper ensemble.
17 * Create a Service configured to connect to the available ZooKeeper instance on the configured client port.
18 * Optionally apply a [Pod Anti-Affinity](https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#inter-pod-affinity-and-anti-affinity-beta-feature) to spread the ZooKeeper ensemble across nodes.
19 * Optionally start JMX Exporter and Zookeeper Exporter containers inside Zookeeper pods.
20 * Optionally create a job which creates Zookeeper chroots (e.g. `/kafka1`).
22 ## Installing the Chart
23 You can install the chart with the release name `zookeeper` as below.
26 $ helm repo add incubator http://storage.googleapis.com/kubernetes-charts-incubator
27 $ helm install --name zookeeper incubator/zookeeper
30 If you do not specify a name, helm will select a name for you.
32 ### Installed Components
33 You can use `kubectl get` to view all of the installed components.
36 $ kubectl get all -l app=zookeeper
38 LAST DEPLOYED: Wed Apr 11 17:09:48 2018
43 ==> v1beta1/PodDisruptionBudget
44 NAME MIN AVAILABLE MAX UNAVAILABLE ALLOWED DISRUPTIONS AGE
48 NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
49 zookeeper-headless ClusterIP None <none> 2181/TCP,3888/TCP,2888/TCP 2m
50 zookeeper ClusterIP 10.98.179.165 <none> 2181/TCP 2m
52 ==> v1beta1/StatefulSet
53 NAME DESIRED CURRENT AGE
57 1. `statefulsets/zookeeper` is the StatefulSet created by the chart.
58 1. `po/zookeeper-<0|1|2>` are the Pods created by the StatefulSet. Each Pod has a single container running a ZooKeeper server.
59 1. `svc/zookeeper-headless` is the Headless Service used to control the network domain of the ZooKeeper ensemble.
60 1. `svc/zookeeper` is a Service that can be used by clients to connect to an available ZooKeeper server.
63 You can specify each parameter using the `--set key=value[,key=value]` argument to `helm install`.
65 Alternatively, a YAML file that specifies the values for the parameters can be provided while installing the chart. For example,
68 $ helm install --name my-release -f values.yaml incubator/zookeeper
73 - You can find all user-configurable settings, their defaults and commentary about them in [values.yaml](values.yaml).
78 The image used for this chart is based on Ubuntu 16.04 LTS. This image is larger than Alpine or BusyBox, but it provides glibc, rather than ulibc or mucl, and a JVM release that is built against it. You can easily convert this chart to run against a smaller image with a JVM that is built against that image's libc. However, as far as we know, no Hadoop vendor supports, or has verified, ZooKeeper running on such a JVM.
81 The Java Virtual Machine used for this chart is the OpenJDK JVM 8u111 JRE (headless).
84 The ZooKeeper version is the latest stable version (3.4.10). The distribution is installed into /opt/zookeeper-3.4.10. This directory is symbolically linked to /opt/zookeeper. Symlinks are created to simulate a rpm installation into /usr.
87 You can test failover by killing the leader. Insert a key:
89 $ kubectl exec zookeeper-0 -- /opt/zookeeper/bin/zkCli.sh create /foo bar;
90 $ kubectl exec zookeeper-2 -- /opt/zookeeper/bin/zkCli.sh get /foo;
93 Watch existing members:
95 $ kubectl run --attach bbox --image=busybox --restart=Never -- sh -c 'while true; do for i in 0 1 2; do echo zk-${i} $(echo stats | nc <pod-name>-${i}.<headless-service-name>:2181 | grep Mode); sleep 1; done; done';
103 Delete Pods and wait for the StatefulSet controller to bring them back up:
105 $ kubectl delete po -l app=zookeeper
106 $ kubectl get po --watch-only
107 NAME READY STATUS RESTARTS AGE
108 zookeeper-0 0/1 Running 0 35s
109 zookeeper-0 1/1 Running 0 50s
110 zookeeper-1 0/1 Pending 0 0s
111 zookeeper-1 0/1 Pending 0 0s
112 zookeeper-1 0/1 ContainerCreating 0 0s
113 zookeeper-1 0/1 Running 0 19s
114 zookeeper-1 1/1 Running 0 40s
115 zookeeper-2 0/1 Pending 0 0s
116 zookeeper-2 0/1 Pending 0 0s
117 zookeeper-2 0/1 ContainerCreating 0 0s
118 zookeeper-2 0/1 Running 0 19s
119 zookeeper-2 1/1 Running 0 41s
122 Check the previously inserted key:
124 $ kubectl exec zookeeper-1 -- /opt/zookeeper/bin/zkCli.sh get /foo
125 ionid = 0x354887858e80035, negotiated timeout = 30000
129 WatchedEvent state:SyncConnected type:None path:null
134 ZooKeeper can not be safely scaled in versions prior to 3.5.x. This chart currently uses 3.4.x. There are manual procedures for scaling a 3.4.x ensemble, but as noted in the [ZooKeeper 3.5.2 documentation](https://zookeeper.apache.org/doc/r3.5.2-alpha/zookeeperReconfig.html) these procedures require a rolling restart, are known to be error prone, and often result in a data loss.
136 While ZooKeeper 3.5.x does allow for dynamic ensemble reconfiguration (including scaling membership), the current status of the release is still alpha, and 3.5.x is therefore not recommended for production use.
139 * StatefulSet and PodDisruptionBudget are beta resources.
140 * Only supports storage options that have backends for persistent volume claims.