configure-yaml

YAML Configuration

The samples in this module demonstrate how to configure a Hazelcast Jet cluster with YAML configuration.

Configuration Lookup

Creating member instance with Jet.newJetInstance() looks for configuration files in multiple locations both in XML and YAML format. XML configuration takes precedence over YAML configuration in all locations resulting the following lookup order:

1. The configuration passed in hazelcast.jet.config JVM argument, either XML or YAML
2. hazelcast-jet.xml on the classpath
3. hazelcast-jet.xml in the working directory
4. hazelcast-jet.yaml on the classpath
5. hazelcast-jet.yaml in the working directory
6. default configuration hazelcast-jet-default.xml

Similarly, the (Java) client instances created with Jet.newJetClient() follows the same lookup logic and order:

1. The configuration passed in hazelcast.client.config JVM argument, either XML or YAML
2. hazelcast-client.xml on the classpath
3. hazelcast-client.xml in the working directory
4. hazelcast-client.yaml on the classpath
5. hazelcast-client.yaml in the working directory
6. default configuration hazelcast-jet-client-default.xml

The sample ConfigLookup demonstrates how the configuration files are located on the classpath and how to use the locator logic to take only YAML configuration files into account.

Loading YAML Configuration Without Lookup

If it is known that the cluster will be configured with YAML configuration and no need for using the location logic shown in the first sample, the following YAML-specific config loader utility methods on the JetConfig class can be used:

• JetConfig.loadFromClasspath() : loads the configuration from the classpath based on the provided filename
• JetConfig.loadFromFile() : loads the configuration from the file system based on the provided filename
• JetConfig.loadYamlFromStream(): loads the configuration from the provided input stream
• JetConfig.loadYamlFromString(): loads the configuration from the provided String containing YAML configuration

The sample YamlJetConfigClasspath loads the jet configuration hazelcast-jet-sample.yaml from the classpath and demonstrates variable replacement in YAML configuration by defining the backup count and metrics configuration in variables taken from the system properties and then from a provided Properties instance.

Full YAML Configuration Example

There is a full example YAML configuration in the distributed Hazelcast Jet jars, named hazelcast-jet-full-example.yaml. In the lack of schema definitions and hence lack of auto-completion in IDEs this example file can be used for reference when writing YAML configuration.