System Configuration

Implementation

AURA uses Typesafe's Config library and the HOCON syntax for configuration.

Configuration Hierarchy

Immutable configuration objects are created at start up time and passed to the various system components. A configuration object is assembled through a hierarchical merge and subsequent resolve of the following configuration layers (higher number in the list means higher priority):

N	Name	What	Description
1	reference.${type}.conf	CP resource	Default values.
2	runtime values	dynamic	Current Runtime values.
3	profile.${aura.profile}.conf	CP resource	A config profile for testing (optional).
4	${aura.path.config}/aura.${type}.conf	File	User-defined values.
5	system properties	Dynamic	Current System properties.

Configuration Types

The ${type} parameter referred in the name column above identifies the type of configuration to be loaded. Possible type options are:

Type Value	Used By
tm	TaskManager instances.
wm	WorkloadManager instances.
client	AuraClient instances.
simulator	LocalClusterSimulator instances.

The configuration options for a particular configuration type can be found in the corresponding reference.${type}.conf classpath resource. By default, all reference resources include a common configuration resource located named reference.conf and assign the entries under the default.* namespace to a configuration key coinciding with the current type (e.g. wm.io will inherit the default.io configuration).

Configuration Structure

The following table describes the main configuration namespaces used in the system. Paths starting with ${type} exist for the tm, wm, and client configuration types.

Key	Description
${type}.io.local	Local buffer and channel configuration.
${type}.io.tcp	TCP packats configuration.
${type}.io.netty	Netty manager configuration.
${type}.io.rpc	RPC servers configuration.
${type}.io.event	Kryo events.
${type}.io.connection	Channel connection configuration.
${type}.machine	Machine descriptor for the current instance.
zookeeper	Zookeper server configuration.
simulator	Configuration for the cluster simulator.

Configuration Profiles

While reference.${type}.conf files can be used to override configuration parameters on a particular development or production environment, configuration profiles can be used to additionally load a resource named profile.${aura.profile}.conf from the aura-core module.

This can be useful when running integration tests on a CI server with limited resources. To use a configuration profile, set the aura.profile System property when you run the tests:

mvn -Daura.profile=travis test

Additionally, profile.user.conf is ignored by git, so you can use e.g. the profile.default.conf as a starting point for your own configuration by copying it to the same location.