Apache Zookeeper

In order to setup Zookeeper cluster, we need to prepare virtual machines and group them into quorum. We need to do this because Zookeeper insists on having all members of cluster known in advance and having quorum neatly solves this issue.

Emphasized lines can be removed from final blueprint if template variables have their default value.

node_templates:

  ${ZOOKEEPER}_firewall:
    type: dice.firewall_rules.zookeeper.Server

  ${ZOOKEEPER}_vm:
    type: dice.hosts.ubuntu.${HOST_SIZE}
    instances:
      deploy: ${ZOOKEEPER_INSTANCE_COUNT}
    relationships:
      - type: dice.relationships.ProtectedBy
        target: ${ZOOKEEPER}_firewall

  ${ZOOKEEPER}_quorum:
    type: dice.components.zookeeper.Quorum
    relationships:
      - type: dice.relationships.zookeeper.QuorumContains
        target: ${ZOOKEEPER}_vm

  ${ZOOKEEPER}:
    type: dice.components.zookeeper.Server
    properties:
      configuration: ${ZOOKEEPER_CONFIGURATION}
    relationships:
      - type: dice.relationships.ContainedIn
        target: ${ZOOKEEPER}_vm
      - type: dice.relationships.zookeeper.MemberOfQuorum
        target: ${ZOOKEEPER}_quorum

Template variables

ZOOKEEPER

The name of the Zookeeper instance. This is usually set to zookeeper or something similar.

ZOOKEEPER_INSTANCE_COUNT

Number of Zookeeper instances that should be in the cluster. This should be set to some odd number (3 and 5 are popular and safe choices for production environments). For testing purposes, setting this to 1 is acceptable.

ZOOKEEPER_CONFIGURATION

A dictionary containing the configuration for the Zookeeper instance. For valid values consult Zookeeper’s documentation. If no custom configuration is needed (as is the case most of the time), set this property to empty dictionary {}. Example:

configuration:
  tickTime: 1500
  initLimit: 10
  syncLimit: 5

HOST_SIZE

Size of the host virtual machine. Available values are Small, Medium and Large.