ZooKeeper Dynamic Configuration

• FluxCapacitor uses ZooKeeper as its dynamic configuration source through archaius-zookeeper.
• Changes to these ZK-based properties will be picked up dynamically at runtime using ZK's watcher/callback functionality.
• [ZooKeeperConfigurationSource] (https://github.com/Netflix/archaius/blob/master/archaius-zookeeper/src/main/java/com/netflix/config/source/ZooKeeperConfigurationSource.java)

Configuring ZooKeeperConfigurationSource

• This implementation requires the path to the ZK root parent node that contains the hierarchy of configuration properties. An example is /[my-app]/config
• Properties are direct ZK child nodes of the root parent ZK node. An example ZK child property node is /[my-app]/config/com.fluxcapacitor.my.property
• The value is stored in the ZK child property node and can be updated at any time.
• All servers will receive a ZK Watcher callback and automatically update their value similar to other dynamic configuration sources (ie. DynamoDB, etc.)
• Any node created or updated under this node - even dynamically at runtime - will be accessible through the archaius dynamic property framework.

Example Configuration

String zkConfigRootPath = "/[my-app]/config";

CuratorFramework client CuratorFrameworkFactory.newClient(zkConnectionString,
        new ExponentialBackoffRetry(1000, 3));

ZooKeeperConfigurationSource zkConfigSource = new ZooKeeperConfigurationSource(client, zkConfigRootPath);
zkConfigSource.start();

DynamicWatchedConfiguration zkDynamicConfig = new DynamicWatchedConfiguration(zkConfigSource);

ConfigurationManager.install(zkDynamicConfig);

The property value is retrieved from the /[my-app]/config/com.fluxcapacitor.my.property ZK node:

String myProperty = DynamicPropertyFactory.getInstance()
    .getStringProperty("com.fluxcapacitor.my.property", "<none>")
    .get();

Examples in Practice

• [Flux Capacitor] (https://github.com/cfregly/fluxcapacitor)