Configuring Astrix

This is a draft

Configuration

Astrix ships with a small standalone configuration framework called DynamicConfig. Each AstrixContext has an associated instance of DynamicConfig which is used to read configuration properties at runtime. A configuration property is resolved in the following order:

1. Custom ConfigSource's
2. System properties
3. Programmatic configuration set on AstrixConfigurer
4. META-INF/astrix/settings.properties
5. Default values

Astrix uses the first value found for a given Setting. Hence the custom configuration sources takes precedence over system properties, which takes precedence over programmatic configuration and so on. The custom configuration is plugable by implementing the ConfigSource and/or DynamicConfigSource spi. By default Astrix will not use any external configuration.

Custom Configuration Sources

By default Astrix only reads the well-known configuration sources (2 - 5 above). You can get an AstrixContext to read your custom configuration sources by passing an instance of DynamicConfig to the AstrixContext. There are two ways to do this:

• Set the instance using AstrixConfigurer.setConfig
• Define a com.avanza.astrix.context.AstrixDynamicConfigFactory property in any of the well-known configuration sources

AstrixConfigurer.setConfig

The AstrixConfigurer.setConfig property allows passing an instance of DynamicConfig to the AstrixContext. Any property defined in this DynamicConfig instance will take precedence over all of the well-known configuration sources above.

Example

DynamicConfig customConfig = DynamicConfig.create(new ArchaiusConfigSource());
astrixConfigurer.setConfig(customConfig);

AstrixDynamicConfigFactory

The other way to define your custom configuration sources is to implement AstrixDynamicConfigFactory. Astrix queries all well-known configuration sources for a "com.avanza.astrix.context.AstrixDynamicConfigFactory" property. If that property is defined, Astrix creates an instance of the defined factory and uses it to create a DynamicConfig instance with the custom configuration sources. Note that a AstrixDynamicConfigFactory will be totally ignored if a DynamicConfig instance is set using AstrixConfigurer.setConfig as described above.

Example

public class CustomConfigFactory implements AstrixDynamicConfigFactory {
	public DynamicConfig create() {
		return DynamicConfig.create(new ArchaiusConfigSource());
	}
}

# content of META-INF/astrix/settings.properties
com.avanza.astrix.context.AstrixDynamicConfigFactory=com.mycorp.astrix.ext.CustomConfigFactory

System Properties

Astrix allows overriding/defining any setting using system properties. For instance you can define what service registry to use from the command line:

Example

> java -jar my-service.jar -DAstrixServiceRegistry.serviceUri=gs-remoting:jini://*/*/service-registry-space?groups=my-group

Programmatic configuration

All settings may be set programmatically on a AstrixConfigurer/AstrixFramworkBean:

Example

@Bean
public AstrixFrameworkBean astrix() {
	AstrixFrameworkBean astrix = new AstrixFrameworkBean();
	astrix.set(AstrixSettings.SERVICE_REGISTRY_URI, "gs-remoting:jini://*/*/service-registry-space?groups=my-group");
	return astrix;
}

META-INF/astrix/settings.properties

The settings.properties file provides a convenient way to override the default value for each setting in Astrix by adding a META-INF/astrix/settings.properties file to the classpath. It could be used to set corporate wide default values by sharing a jar containing a settings.properties file. For instance it could be used to say that "com.mycorp" should be scanned for api-providers, avoiding the need to duplicate such configuration on every instance of AstrixConfigurer throughout an enterprise.

At Avanza we share a single "corporate" jar containing the default settings used at Avanza:

Example content of META-INF/astrix/settings.properties

# Custom ConfigurationFactory used to add custom configuration sources
com.avanza.astrix.context.AstrixDynamicConfigFactory=se.avanzabank.aza.astrix.integration.AvanzaAstrixDynamicConfigFactory
# Always scan se.avanzabank,nu.placera for @AstrixApiProvider annotated classes
AstrixApiProviderScanner.basePackage=se.avanzabank,nu.placera

Settings

The DynamicConfig instance associated with a AstrixContext is used to read settings at runtime. Astrix distinguishes between two types of settings. The first one are AstrixSettings which are global to a AstrixContext, and the other one are AstrixBeanSettings which applies to individual Astrix beans.

List of AstrixSettings

This is a list of the most common AstrixSettings

AstrixSetting (configuration property name)	Default Value	Description
BEAN_BIND_ATTEMPT_INTERVAL (StatefulAstrixBeanInstance.beanBindAttemptInterval)	10 000	The intervall (in milliseconds) between consecutive bind attemps when a ServicBeanInstance is in UNBOUND state
SERVICE_REGISTRY_URI (AstrixServiceRegistry.serviceUri)	(none)	ServiceUri used to bind to the service-registry.
DYNAMIC_CONFIG_FACTORY (com.avanza.astrix.context.AstrixDynamicConfigFactory)	(none)

List of AstrixBeanSettings

Overriding Default AstrixBeanSettings (@DefaultBeanSettings)