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Overview

The Eureka Server provides service discovery and registration capabilities for all microservices in the StreamLine Logistics platform. Built on Netflix Eureka, it acts as a central registry where services register themselves and discover other services dynamically.
Eureka Server runs on port 8761 and serves as the backbone of service-to-service communication in the microservices architecture.

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Configuration

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Application Configuration

The Eureka Server is configured via application.yml: 
server:
  port: 8761

spring:
  application:
    name: msvc-eureka
  config:
    import: "optional:configserver:http://localhost:8888"

eureka:
  instance:
    hostname: eureka-server
  client:
    register-with-eureka: false
    fetch-registry: false
    server-url:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

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Key Configuration Properties

PropertyValueDescription
server.port8761Standard Eureka Server port
spring.application.namemsvc-eurekaService identifier
eureka.client.register-with-eurekafalsePrevents server from registering with itself
eureka.client.fetch-registryfalseServer doesn’t need to fetch registry
eureka.instance.hostnameeureka-serverHostname used in Docker environment
The register-with-eureka and fetch-registry properties are set to false because this is the Eureka Server itself, not a client. Client services will have these set to true.

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Spring Boot Application

The Eureka Server is enabled with a single annotation: 
package com.microservice.eureka;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@EnableEurekaServer
@SpringBootApplication
public class MicroserviceEurekaApplication {

    public static void main(String[] args) {
        SpringApplication.run(MicroserviceEurekaApplication.class, args);
    }
}
The @EnableEurekaServer annotation activates all Eureka Server functionality, including:
  • Service registration endpoints
  • Service discovery API
  • Health monitoring dashboard
  • Registry replication (in cluster mode)

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Docker Configuration

The Eureka Server runs as a Docker container in the microservices network: 
eureka-server:
  container_name: eureka-server
  build:
    context: .
    dockerfile: ./microservice-eureka/Dockerfile
  image: eureka-service:latest
  ports:
    - "8761:8761"
  networks:
    - microservices-network
All microservices define depends_on: eureka-server to ensure the registry is available before services attempt to register.

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Service Registration

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How Services Register

Client services (Order, Inventory, Tracking) register with Eureka by including these dependencies: 
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
And configuring the Eureka client in their application.yml: 
eureka:
  instance:
    hostname: eureka-server
  client:
    service-url:
      defaultZone: http://${eureka.instance.hostname}:8761/eureka/

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Registration Process

  1. Service Startup: When a microservice starts, it sends a registration request to Eureka Server
  2. Heartbeats: Services send heartbeat signals every 30 seconds (default) to maintain their registration
  3. Renewal: Eureka expects renewals every 30 seconds; services not renewing are evicted after 90 seconds
  4. Metadata: Services register with metadata including hostname, port, health check URL, and custom metadata

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Registered Services

The following services register with Eureka:
  • msvc-order (Order Service) - Port 8090
  • msvc-inventory (Inventory Service) - Port 9090
  • msvc-tracking (Tracking Service) - Port 8091

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Service Discovery

Services discover each other using Eureka’s registry:

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Using OpenFeign

StreamLine Logistics uses OpenFeign for inter-service communication. Feign clients automatically resolve service names via Eureka: 
@FeignClient(name = "msvc-inventory")
public interface InventoryClient {
    @PostMapping("/api/inventory/check")
    InventoryResponse checkStock(@RequestBody InventoryRequest request);
}
The name = "msvc-inventory" is resolved by querying Eureka for instances of the inventory service.

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Eureka Dashboard

Access the Eureka web dashboard at: 
http://localhost:8761
The dashboard displays:
  • Registered service instances
  • Instance status (UP, DOWN, STARTING)
  • Instance metadata (hostname, IP, port)
  • Lease information and last heartbeat
  • General Eureka Server information
The dashboard is for development and monitoring. In production, consider securing it with Spring Security or disabling it entirely.

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Dependencies

From pom.xml: 
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-config</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
    </dependency>
</dependencies>
Spring Cloud Version: 2025.1.0

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Integration with Config Server

Eureka Server optionally integrates with the Config Server for centralized configuration: 
spring:
  config:
    import: "optional:configserver:http://localhost:8888"
The optional: prefix allows Eureka to start even if Config Server is unavailable, ensuring resilience during startup.

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High Availability

For production deployments, consider:
  • Multiple Eureka Instances: Deploy 2-3 Eureka servers for redundancy
  • Peer Replication: Configure Eureka servers to replicate registry data
  • Load Balancing: Use a load balancer in front of Eureka instances
  • Self-Preservation Mode: Eureka’s default protection against network partitions

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Troubleshooting

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Services Not Registering

  1. Check network connectivity to port 8761
  2. Verify eureka.client.service-url.defaultZone configuration
  3. Review service logs for registration errors
  4. Ensure Eureka Server started before client services

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Services Showing as DOWN

  1. Check service health endpoint (/actuator/health)
  2. Verify heartbeat configuration
  3. Review network latency between service and Eureka
  4. Check for self-preservation mode activation

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Dashboard Not Accessible

  1. Verify server is running: docker ps | grep eureka-server
  2. Check port mapping: 8761:8761
  3. Ensure no firewall blocking port 8761
  4. Review Eureka Server logs for startup errors

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Security Considerations

In production environments, secure Eureka Server with:
  • Spring Security authentication
  • HTTPS/TLS encryption
  • Network-level access controls (security groups, firewalls)
  • Actuator endpoint protection
  • API Gateway - Routes requests using Eureka service discovery
  • Config Server - Provides centralized configuration to Eureka and all services

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