🌍 Travel Bank – Centralized Config Server with Dynamic Refresh Support (v4.0)

Welcome to the Travel Bank Configuration Server, now upgraded to support dynamic runtime refresh, event-driven configuration updates, and health probes for better resilience and scalability across all microservices.

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📌 Project Continuity

This project is an evolution of the following previous versions:

• 🔗 TRAVEL-BANK_Microservices_v.1.0
• 🔗 TRAVEL-BANK_Docker_v.2.0
• 🔗 TRAVEL-BANK_ConfigManagement_v.3.0

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✨ What’s New in v4.2?

✅ Centralized Config Server with Native File Support

spring:
  application:
    name: "configserver"
  profiles:
    active: native
  cloud:
    config:
      server:
        native:
          search-locations: "file:///D://GitHub_Public//configurationfiles"
server:
  port: 8071

Each microservice like accounts, loans, and cards now fetches configuration from this central server using:

spring.application.name=accounts
spring.config.import=optional:configserver:http://localhost:8071

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🔄 Dynamic Configuration Refresh at Runtime

In typical Spring Boot apps, config changes require a restart. Spring Cloud Config allows hot reload with the /refresh or /busrefresh endpoints:

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🔃 Approach 1: Refresh Using /refresh Endpoint

✅ Steps

1. Add actuator dependency to each microservice (accounts, loans, cards):

   <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-actuator</artifactId>
   </dependency>

2. Enable refresh endpoint in application.yml:

   management:
     endpoints:
       web:
         exposure:
           include: refresh

3. Trigger refresh via POST:

   curl -X POST http://localhost:<port>/actuator/refresh

4. ✅ No restart required — configuration updates take effect immediately!

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📱 Approach 2: Refresh Using Spring Cloud Bus + RabbitMQ

✅ Steps

1. Add dependencies to all services:

   <dependency>
       <groupId>org.springframework.cloud</groupId>
       <artifactId>spring-cloud-starter-bus-amqp</artifactId>
   </dependency>

2. Enable busrefresh endpoint in application.yml:

   management:
     endpoints:
       web:
         exposure:
           include: busrefresh

3. Run RabbitMQ via Docker:

   docker run -d -p 5672:5672 -p 15672:15672 --name rabbitmq rabbitmq:management

4. Trigger refresh across all services:

   curl -X POST http://localhost:<port>/actuator/busrefresh

✅ Works across all instances and services connected to the Bus.

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🔔 Approach 3: Fully Automated Refresh using Spring Cloud Config Monitor + GitHub Webhooks

✅ Steps

1. Add monitor dependency to the config server:

   <dependency>
       <groupId>org.springframework.cloud</groupId>
       <artifactId>spring-cloud-config-monitor</artifactId>
   </dependency>

2. Enable /monitor endpoint (already enabled with actuator).

3. Configure GitHub webhook:

   • Target URL: http://<config-server>/monitor
   • Content Type: application/json
   • Trigger on: push

✅ When a change is pushed to GitHub config repo, refresh is automatically triggered across all services via RabbitMQ!

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📶 Probes: Liveness and Readiness in Spring Boot

Spring Boot Actuator supports health probes to monitor container/app status:

Probe Type	Path	Description
Liveness	/actuator/health/liveness	Is the app alive? Restart if fails
Readiness	/actuator/health/readiness	Can the app handle traffic?

Enable in application.yml:

management:
  endpoint:
    health:
      probes:
        enabled: true
  endpoints:
    web:
      exposure:
        include: health

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🔍 Architecture Summary

↺ Manual Refresh

GitHub Config Repo --> Push config
                     ↓
Config Server <---- /refresh
                     ↓
Microservice reloads updated config

🖡 Automated Refresh with Spring Cloud Bus + Monitor

GitHub Config Repo --> Push config
                     ↓ webhook
Config Server <---- /monitor
                     ↓ Bus Event
Microservices <---- /busrefresh (auto)

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💡 Benefits

• 🔄 Real-time config refresh without restarts
• 🕸️ Event-driven updates with RabbitMQ
• 🛡️ Robust health checks via probes
• 📆 Git-based externalized config management (future)
• 🤖 Monitor-based automation with GitHub Webhooks

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🚀 What’s Next in v5.x?

• ✅ Move to Git-based configuration source
• 🔒 Integrate Spring Cloud Vault for secrets
• 🌐 Deploy Config Server to AWS EC2 or EKS
• 🔐 Add role-based config access controls

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🙌 Contribution

We welcome contributions, feedback, and suggestions! Please feel free to fork, create issues, or open PRs.

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📜 License

MIT License © Vinay Steja

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Built with ❤️ by Vinay Teja and Spring Cloud enthusiasts.