ravisharda / zookeeper-operator

Kubernetes Operator for Zookeeper

Zookeeper Operator

Project status: alpha

The project is currently alpha. While no breaking API changes are currently planned, we reserve the right to address bugs and change the API before the project is declared stable.

Table of Contents

• Overview
• Requirements
• Usage
  • Installation of the Operator
  • Deploy a sample Zookeeper Cluster
  • Uninstall the Zookeeper Cluster
  • Uninstall the Operator
• Development
  • Build the Operator Image
  • Direct Access to Cluster
  • Run the Operator Locally
  • Installation on GKE

Overview

This operator runs a Zookeeper 3.5 cluster, and uses Zookeeper dynamic reconfiguration to handle node membership.

The operator itself is built with the Operator framework.

Requirements

• Access to a Kubernetes v1.9.0+ cluster

Usage

Install the operator

Note: if you are running on Google Kubernetes Engine (GKE), please check this first.

Register the ZookeeperCluster custom resource definition (CRD).

$ kubectl create -f deploy/crds/zookeeper_v1beta1_zookeepercluster_crd.yaml

You can choose to enable Zookeeper operator for all namespaces or just for the a specific namespace. The example is using the default namespace, but feel free to edit the Yaml files and use a different namespace.

Create the operator role and role binding.

// default namespace
$ kubectl create -f deploy/default_ns/rbac.yaml

// all namespaces
$ kubectl create -f deploy/all_ns/rbac.yaml

Deploy the Zookeeper operator.

// default namespace
$ kubectl create -f deploy/default_ns/operator.yaml

// all namespaces
$ kubectl create -f deploy/all_ns/operator.yaml

Verify that the Zookeeper operator is running.

$ kubectl get deploy
NAME                 DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
zookeeper-operator   1         1         1            1           12m

Deploy a sample Zookeeper cluster

Create a Yaml file called zk.yaml with the following content to install a 3-node Zookeeper cluster.

apiVersion: "zookeeper.pravega.io/v1beta1"
kind: "ZookeeperCluster"
metadata:
  name: "example"
spec:
  size: 3

$ kubectl create -f zk.yaml

Verify that the cluster instances and its components are running.

$ kubectl get zk
NAME      AGE
example   15s

$ kubectl get all -l app=example
NAME                   DESIRED   CURRENT   AGE
statefulsets/example   3         3         2m

NAME           READY     STATUS    RESTARTS   AGE
po/example-0   1/1       Running   0          2m
po/example-1   1/1       Running   0          1m
po/example-2   1/1       Running   0          1m

NAME                   TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)             AGE
svc/example-client     ClusterIP   10.31.243.173   <none>        2181/TCP            2m
svc/example-headless   ClusterIP   None            <none>        2888/TCP,3888/TCP   2m

Uninstall the Zookeeper cluster

$ kubectl delete -f zk.yaml

Uninstall the operator

Note that the Zookeeper clusters managed by the Zookeeper operator will NOT be deleted even if the operator is uninstalled.

To delete all clusters, delete all cluster CR objects before uninstalling the operator.

$ kubectl delete -f deploy/default_ns
// or, depending on how you deployed it
$ kubectl delete -f deploy/all_ns

Development

Build the operator image

Requirements:

• Go 1.10+

Use the make command to build the Zookeeper operator image.

$ make build

That will generate a Docker image with the format <latest_release_tag>-<number_of_commits_after_the_release> (it will append-dirty if there are uncommitted changes). The image will also be tagged as latest.

Example image after running make build.

The Zookeeper operator image will be available in your Docker environment.

$ docker images pravega/zookeeper-operator

REPOSITORY                    TAG              IMAGE ID        CREATED         SIZE   

pravega/zookeeper-operator    0.1.1-3-dirty    2b2d5bcbedf5    10 minutes ago  41.7MB

pravega/zookeeper-operator    latest           2b2d5bcbedf5    10 minutes ago  41.7MB 

Optionally push it to a Docker registry.

docker tag pravega/zookeeper-operator [REGISTRY_HOST]:[REGISTRY_PORT]/pravega/zookeeper-operator
docker push [REGISTRY_HOST]:[REGISTRY_PORT]/pravega/zookeeper-operator

where:

• [REGISTRY_HOST] is your registry host or IP (e.g. registry.example.com)
• [REGISTRY_PORT] is your registry port (e.g. 5000)

Direct access to the cluster

For debugging and development you might want to access the Zookeeper cluster directly. For example, if you created the cluster with name example in the default namespace you can forward the Zookeeper port from any of the pods (e.g. example-0) as follows:

$ kubectl port-forward -n default example-0 2181:2181

Run the operator locally

You can run the operator locally to help with development, testing, and debugging tasks.

The following command will run the operator locally with the default Kubernetes config file present at $HOME/.kube/config. Use the --kubeconfig flag to provide a different path.

$ operator-sdk up local

Installation on Google Kubernetes Engine

The Operator requires elevated privileges in order to watch for the custom resources.

According to Google Container Engine docs:

Ensure the creation of RoleBinding as it grants all the permissions included in the role that we want to create. Because of the way Container Engine checks permissions when we create a Role or ClusterRole.

An example workaround is to create a RoleBinding that gives your Google identity a cluster-admin role before attempting to create additional Role or ClusterRole permissions.

This is a known issue in the Beta release of Role-Based Access Control in Kubernetes and Container Engine version 1.6.

On GKE, the following command must be run before installing the operator, replacing the user with your own details.

$ kubectl create clusterrolebinding your-user-cluster-admin-binding --clusterrole=cluster-admin [email protected]