isabella232 / layer-apache-zookeeper

The Apache Zookeeper charm layer (superseded by the Apache Bigtop Zookeeper charm: https://github.com/apache/bigtop/tree/master/bigtop-packages/src/charm/zookeeper/layer-zookeeper)

NOTICE

The Apache Zookeeper charm has been superseded by the Zookeeper charm from Apache Bigtop:

https://github.com/apache/bigtop/tree/master/bigtop-packages/src/charm/zookeeper/layer-zookeeper

This layer-apache-zookeeper repository does not receive regular updates, and is only here as a reference for legacy deployments.

Overview

Apache ZooKeeper is a high-performance coordination service for distributed applications. It exposes common services such as naming, configuration management, synchronization, and group services in a simple interface so you don't have to write them from scratch. You can use it off-the-shelf to implement consensus, group management, leader election, and presence protocols.

Usage

Deploy a Zookeeper unit. With only one unit, the service will be running in standalone mode:

juju deploy apache-zookeeper zookeeper

Scaling

Running ZooKeeper in standalone mode is convenient for evaluation, some development, and testing. But in production, you should run ZooKeeper in replicated mode. A replicated group of servers in the same application is called a quorum, and in replicated mode, all servers in the quorum have copies of the same configuration file.

Scaling Zookeeper to create a quorum is trivial. The following will add two additional Zookeeper units and will automatically configure them with knowledge of the other quorum members based on their peer relation to one another:

juju add-unit -n 2 zookeeper

Test the deployment

Test if the Zookeeper service is running by using the zkServer.sh script:

juju run --service=zookeeper '/usr/lib/zookeeper/bin/zkServer.sh status'

A successful deployment will report the service mode as either standalone (if only one Zookeeper unit has been deployed) or leader / follower (if a Zookeeper quorum has been formed).

REST API

Zookeeper REST Api can be enabled/disabled either through an action or via a config variable:

juju action do zookeeper/0 start-rest
juju action do zookeeper/0 stop-rest

or

juju set zookeeper rest=true

Integrate Zookeeper into another charm

1. Add following lines to your charm's metadata.yaml:

   requires: zookeeper: interface: zookeeper

2. Add a zookeeper-relation-changed hook to your charm. Example contents:

   from charmhelpers.core.hookenv import relation_get ZK_hostname = relation_get('private-address') ZK_port = relation_get('port')

Contact Information

[email protected]

Help

• Apache Zookeeper home page
• Apache Zookeeper issue tracker
• Juju mailing list
• Juju community