org.apache.druid.discovery

Class NodeRole

java.lang.Object

org.apache.druid.discovery.NodeRole

public class NodeRole
extends Object

Defines the 'role' of a Druid service, utilized to strongly type announcement and service discovery. Originally, this was an enum to add type safety for discovery and announcement purposes, but was expanded into a class to allow for extensibility while retaining the type safety of using defined types instead of raw strings. As such, this class tries to mimic the interface provided by the previous enum. Built in node roles define a name that is distinct from jsonName, and is the previous value which would occur when the enum was used in a 'toString' context. Custom node roles allow extension to participate in announcement and discovery, but are limited to only using jsonName for both toString and JSON serde. The historical context of why the enum was different from ServerType (also called "node type" in various places) is because while they are essentially the same abstraction, merging them could only increase the complexity and drop the code safety, because they name the same types differently ("peon" - "indexer-executor" and "middleManager" - "realtime") and both expose them via JSON APIs. These abstractions can all potentially be merged when Druid updates to Jackson 2.9 that supports JsonAliases, see https://github.com/apache/druid/issues/7152.

Field Summary

Fields

Modifier and Type	Field and Description
static NodeRole	BROKER
static NodeRole	COORDINATOR
static NodeRole	HISTORICAL
static NodeRole	INDEXER
static NodeRole	MIDDLE_MANAGER
static NodeRole	OVERLORD
static NodeRole	PEON
static NodeRole	ROUTER

Constructor Summary

Constructors

Constructor and Description
NodeRole(String jsonName) Create a custom node role.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object o)
static NodeRole	fromJsonName(String jsonName)
String	getJsonName()
int	hashCode()
String	toString()
static NodeRole[]	values() built-in node roles

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

COORDINATOR

public static final NodeRole COORDINATOR

HISTORICAL

public static final NodeRole HISTORICAL

BROKER

public static final NodeRole BROKER

OVERLORD

public static final NodeRole OVERLORD

PEON

public static final NodeRole PEON

ROUTER

public static final NodeRole ROUTER

MIDDLE_MANAGER

public static final NodeRole MIDDLE_MANAGER

INDEXER

public static final NodeRole INDEXER

Constructor Detail

NodeRole

public NodeRole(String jsonName)

Create a custom node role. Known Druid node roles should ALWAYS use the built-in static node roles: (COORDINATOR, OVERLORD, ROUTER, BROKERINDEXER, MIDDLE_MANAGER, HISTORICAL) instead of constructing a new instance.

Method Detail

getJsonName

public String getJsonName()

fromJsonName

public static NodeRole fromJsonName(String jsonName)

toString

public String toString()

Overrides:

toString in class Object

values

public static NodeRole[] values()

built-in node roles

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object