Implementation:Ray project Ray Serve ReplicaContext

Knowledge Sources	Ray Ray Serve
Domains	Model_Serving, Distributed_Computing
Last Updated	2026-02-13 16:00 GMT

Overview

ReplicaContext is a data class that stores per-replica context information accessible via Serve.getReplicaContext(), allowing deployment code to introspect its own identity and configuration at runtime.

Description

ReplicaContext is a simple POJO that holds the deployment name, replica tag, servable object, configuration map, and application name for a running replica. It is created during replica initialization in Serve.setInternalReplicaContext() and stored as a static field, making it accessible from anywhere within the replica's execution context. The class provides standard getter/setter methods for all fields.

Usage

Use ReplicaContext within deployment code to access the current replica's identity (deployment name, replica tag), retrieve the servable object, read configuration properties, or determine the application name. It is obtained by calling Serve.getReplicaContext() and is also used internally by components like LongPollClientFactory to read configuration settings.

Code Reference

Source Location

• Repository: Ray
• File: java/serve/src/main/java/io/ray/serve/replica/ReplicaContext.java

Signature

public class ReplicaContext {

    public ReplicaContext(
        String deploymentName,
        String replicaTag,
        Object servableObject,
        Map<String, String> config,
        String appName)
}

Import

import io.ray.serve.replica.ReplicaContext;

I/O Contract

Constructor Parameters

Parameter	Type	Description
deploymentName	String	Name of the deployment this replica belongs to
replicaTag	String	Unique tag identifying this specific replica instance
servableObject	Object	The user-defined servable object (deployment class instance)
config	Map<String, String>	Configuration properties for the replica
appName	String	Name of the Ray Serve application

Key Methods

Method	Return Type	Description
getDeploymentName() / setDeploymentName(String)	String / void	Gets or sets the deployment name
getReplicaTag() / setReplicaTag(String)	String / void	Gets or sets the unique replica tag
getServableObject() / setServableObject(Object)	Object / void	Gets or sets the user-defined servable object
getConfig() / setConfig(Map<String, String>)	Map<String, String> / void	Gets or sets the configuration map
getAppName() / setAppName(String)	String / void	Gets or sets the application name

Usage Examples

// Access replica context from within a deployment handler
ReplicaContext ctx = Serve.getReplicaContext();

String deploymentName = ctx.getDeploymentName();
String replicaTag = ctx.getReplicaTag();
String appName = ctx.getAppName();

logger.info("Running in deployment '{}', replica '{}', app '{}'",
    deploymentName, replicaTag, appName);

// Read configuration properties
Map<String, String> config = ctx.getConfig();
String modelPath = config.get("model_path");

// Access the servable object
Object servable = ctx.getServableObject();

Related Pages

• Environment:Ray_project_Ray_Java_Build_Environment