Discovery Service Configuration - SGIVU Config Repository

The Discovery Service (sgivu-discovery) is a Netflix Eureka server that provides service registry and discovery capabilities for the SGIVU microservices architecture.

Service Overview

Port

8761

Type

Eureka Server

Clients

All microservices

Database

None (in-memory)

Key Features

Service registry for all SGIVU microservices
Health monitoring and heartbeat management
Service instance discovery
Load balancing support
Self-preservation mode for network partition tolerance

Configuration

Server Settings

server:
  port: 8761

Port 8761 is the standard Eureka server port and is used by all services by default.

Eureka Server Configuration

eureka:
  instance:
    hostname: host.docker.internal
  client:
    registerWithEureka: false
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

Configuration Breakdown

hostname: The hostname used for Eureka server registration
registerWithEureka: false: The Eureka server does not register itself
fetchRegistry: false: The Eureka server does not fetch registry from other servers
defaultZone: Points to itself for standalone operation

Standalone vs. Cluster Mode

The current configuration runs Eureka in standalone mode (single server).

Standalone Mode (Current)

eureka:
  client:
    registerWithEureka: false
    fetchRegistry: false

Standalone mode is suitable for development and small deployments. For production high availability, consider clustering multiple Eureka servers.

Cluster Mode (Future)

For production environments with multiple Eureka instances:

eureka:
  client:
    registerWithEureka: true
    fetchRegistry: true
    serviceUrl:
      defaultZone: http://eureka-1:8761/eureka/,http://eureka-2:8761/eureka/

Docker Networking

eureka:
  instance:
    hostname: host.docker.internal

The host.docker.internal hostname allows services running in Docker containers to communicate with the Eureka server.

Service Registration

All microservices register with Eureka using this URL pattern:

# In client services
eureka:
  client:
    service-url:
      defaultZone: ${EUREKA_URL:http://sgivu-discovery:8761/eureka}

Environment-Specific Configuration

Development
Production

Development environment uses the same base configuration with no overrides:

# sgivu-discovery-dev.yml is empty
# Uses base configuration from sgivu-discovery.yml

No special configuration needed for development.

Production environment also uses the base configuration:

# sgivu-discovery-prod.yml is empty
# Uses base configuration from sgivu-discovery.yml

Consider adding:

Multiple Eureka instances for HA
Custom peer awareness configuration
Production-specific logging

Service Registry

Eureka maintains a registry of all services:

Service	Instance ID Pattern
sgivu-auth	`hostname:sgivu-auth:random-value`
sgivu-gateway	`hostname:sgivu-gateway:random-value`
sgivu-user	`hostname:sgivu-user:random-value`
sgivu-client	`hostname:sgivu-client:random-value`
sgivu-vehicle	`hostname:sgivu-vehicle:random-value`
sgivu-purchase-sale	`hostname:sgivu-purchase-sale:random-value`

The random value in instance IDs allows multiple instances of the same service to run simultaneously.

Eureka Dashboard

The Eureka server provides a web dashboard for monitoring:

http://localhost:8761/

The dashboard shows:

Registered service instances
Instance status (UP, DOWN, OUT_OF_SERVICE)
Renewal statistics
General server information

Dashboard Features

Instances currently registered: List of all registered services
General Info: Server configuration and environment
Instance Info: Detailed information about each instance
Lease expiration: When each instance lease expires
Renewal settings: Heartbeat intervals and timeouts

Health Monitoring

Eureka uses heartbeat mechanism for health monitoring:

Default renewal interval: 30 seconds
Default eviction timeout: 90 seconds
Self-preservation threshold: 85%

In self-preservation mode, Eureka stops evicting instances when renewals drop below threshold, preventing mass eviction during network issues.

Service Discovery

Client services can discover other services using Eureka:

// Example: Discovering User Service
List<ServiceInstance> instances = discoveryClient.getInstances("sgivu-user");

Load Balancing

Eureka integrates with Spring Cloud LoadBalancer for client-side load balancing:

Round-robin distribution by default
Automatic failover to healthy instances
Zone-aware routing (if configured)

Required Environment Variables

The Discovery Service has minimal environment variable requirements:

Variable	Description	Default
`PORT`	Eureka server port	`8761`

All configuration is self-contained in the YAML files. No external dependencies required.

Networking Considerations

Docker Compose

In Docker Compose, services reference Eureka by service name:

services:
  sgivu-discovery:
    ports:
      - "8761:8761"
  
  sgivu-user:
    environment:
      - EUREKA_URL=http://sgivu-discovery:8761/eureka

Kubernetes

In Kubernetes, use service DNS:

env:
  - name: EUREKA_URL
    value: http://sgivu-discovery.default.svc.cluster.local:8761/eureka

High Availability Setup

For production deployments, consider running multiple Eureka instances:

HA Configuration Example

Eureka Instance 1:

eureka:
  instance:
    hostname: eureka-1
  client:
    registerWithEureka: true
    fetchRegistry: true
    serviceUrl:
      defaultZone: http://eureka-2:8761/eureka/,http://eureka-3:8761/eureka/

Eureka Instance 2:

eureka:
  instance:
    hostname: eureka-2
  client:
    registerWithEureka: true
    fetchRegistry: true
    serviceUrl:
      defaultZone: http://eureka-1:8761/eureka/,http://eureka-3:8761/eureka/

Eureka Instance 3:

eureka:
  instance:
    hostname: eureka-3
  client:
    registerWithEureka: true
    fetchRegistry: true
    serviceUrl:
      defaultZone: http://eureka-1:8761/eureka/,http://eureka-2:8761/eureka/

Security Considerations

The current configuration does not include authentication. For production, consider adding Spring Security to protect the Eureka dashboard and API.

Securing Eureka

To add basic authentication:

spring:
  security:
    user:
      name: ${EUREKA_USERNAME}
      password: ${EUREKA_PASSWORD}

Troubleshooting

Services Not Registering

Check network connectivity to port 8761
Verify EUREKA_URL environment variable
Check service logs for registration errors
Verify Eureka server is running

Self-Preservation Mode

If you see “EMERGENCY! EUREKA MAY BE INCORRECTLY CLAIMING INSTANCES ARE UP”:

This is normal during development with frequent restarts
Eureka enters self-preservation to prevent cascade failures
Wait for services to stabilize or disable self-preservation in dev:

eureka:
  server:
    enable-self-preservation: false

Configuration Files

sgivu-discovery.yml - Base configuration (used in all environments)
sgivu-discovery-dev.yml - Empty (no overrides)
sgivu-discovery-prod.yml - Empty (no overrides)

All Services

Gateway

Uses Eureka for routing

Monitoring

Monitor service health

Overview

Getting Started

Service Configuration

Environment Management

Operations

​Service Overview

Port

Type

Clients

Database

​Key Features

​Configuration

​Server Settings

​Eureka Server Configuration

​Standalone vs. Cluster Mode

​Standalone Mode (Current)

​Cluster Mode (Future)

​Docker Networking

​Service Registration

​Environment-Specific Configuration

​Service Registry

​Eureka Dashboard

​Health Monitoring

​Service Discovery

​Load Balancing

​Required Environment Variables

​Networking Considerations

​Docker Compose

​Kubernetes

​High Availability Setup

​Security Considerations

​Securing Eureka

​Troubleshooting

​Services Not Registering

​Self-Preservation Mode

​Configuration Files

​Related Services

All Services

Gateway

Monitoring

Build docs developers (and LLMs) love

Service Overview

Key Features

Configuration

Server Settings

Eureka Server Configuration

Standalone vs. Cluster Mode

Standalone Mode (Current)

Cluster Mode (Future)

Docker Networking

Service Registration

Environment-Specific Configuration

Service Registry

Eureka Dashboard

Health Monitoring

Service Discovery

Load Balancing

Required Environment Variables

Networking Considerations

Docker Compose

Kubernetes

High Availability Setup

Security Considerations

Securing Eureka

Troubleshooting

Services Not Registering

Self-Preservation Mode

Configuration Files

Related Services