ZkMicroProfileConfig

Implementation of a MicroProfile ConfigSource that is backed by Apache Zookeeper.

Using the MicroProfile Configuration API is a really convenient way to configure your application. The standard MicroProfile Confuration Sources are Environment Variables, System Variables and via a microprofile-config.properties file in the Classpath. This project enables MicroProfile Conifugurations to be obtained from Apache Zookeeper. The benefits are that configurations can be shared across applications and a future version will allow applications to subscribe to updates to the conifiguration parameters.

Usage

To use the Zookeeper MicroProfile Config source, add the following to your Maven pom.xml

<dependency>
    <groupId>io.streamzi</groupId>
    <artifactId>ZkMicroProfileConfigSource</artifactId>
    <version>1.0.0-SNAPSHOT</version>
</dependency>

You will need to boostrap your application with the location of your Zookeeper server and a unique identifier for your applciation. Add the following to src/main/resources/META-INF/mircoprofile-config.properties or create equivalent Environment Variables.

io.streamzi.zk.zkUrl=localhost:2181
io.streamzi.zk.applicationId=com.example.my-application

Following this any properties that are looked up via the Config API or Injected will be looked up in Zookeeper in addition to the standard MicroProfile Config locations. The ZKMicroProfileConfigSource has a lower Ordinal than the standard locations and thus will not override property files or Environment Variables.

The ConfigSource will store the following znodes in the specified Zookeeper server /applicationId/propertyName = value.

The snippet below shows how to parameterise your application with either injected values or looking them up using a ConfigProvider

@Inject
@ConfigProperty(name = "propertyName", defaultValue = "default_value")
String strProp;

//Or

final Config cfg = ConfigProvider.getConfig();
final String strProp = cfg.getValue("propertyName", String.class);

Example

An example of how to use the Config Source is supplied in the Example directory:

example/README.adoc

Todo

• Extension that will notify configuration changes

  • Library that uses the notification changes to reconnect to Kafka