How does Spring Cloud Config help in centralized configuration management?

Problem Without Centralized Configuration

In microservices:

  • Each service has its own application.properties

  • Environment changes (dev/qa/prod) require redeployment

  • Configuration drift occurs

  • Security risk (secrets in code)

🔹 What is Spring Cloud Config?

Spring Cloud Config provides externalized, centralized configuration for all microservices.

It uses a Config Server that fetches configuration from:

  • Git (most common)

  • File system

  • Vault

🔹 Architecture

Client Service
⬇
Config Server
⬇
Git Repository

Each microservice fetches config at startup or runtime.

🔹 How It Works (Flow)

  1. Config Server starts

  2. Reads configuration from Git repo

  3. Microservice starts

  4. Microservice fetches config from Config Server

  5. Config is applied based on:

    • application name

    • profile (dev/prod)

🔹 Example Structure (Git)

config-repo/
├── order-service.yml
├── order-service-dev.yml
├── payment-service.yml

🔹 Example Client Configuration

spring:
application:
name: order-service
config:
import: configserver:http://localhost:8888

🔹 Refreshing Config Without Restart

Use:

  • @RefreshScope

  • Actuator /refresh endpoint

@RefreshScope
@Component
public class ConfigBean {
@Value("${discount.rate}")
private int discount;
}

🔹 Advantages

✅ Centralized config
✅ Environment-based config
✅ No redeployment for config change
✅ Secure secrets management
✅ Consistency across services

🔹 Disadvantages

❌ Additional infrastructure
❌ Config Server becomes critical dependency
❌ Needs HA setup

🔹 Real-World Example

💳 Change DB password in Git
→ Refresh Config
→ All services updated without restart

⭐ Interview One-Liner

“Spring Cloud Config externalizes configuration and allows centralized, environment-specific, and dynamic configuration management.”

🔹 Follow-Up Questions Interviewers Ask

  • How do you secure Config Server?

  • Difference between Spring Cloud Config & Kubernetes ConfigMaps?

  • How does @RefreshScope work internally?

Tags:

Leave a Reply