Master Spring Cloud Bus: Dynamic Config Refresh with RabbitMQ

Spring Cloud Bus Overview

Spring Cloud Bus uses a lightweight message broker to connect services in a microservice architecture, allowing broadcast of state changes such as configuration updates. It works with Spring Cloud Config to enable dynamic configuration refresh and supports RabbitMQ and Kafka; the example below uses RabbitMQ.

RabbitMQ Installation

Install Erlang (download from http://erlang.org/download/otp_win64_21.3.exe ).

Install RabbitMQ (download from https://dl.bintray.com/rabbitmq/all/rabbitmq-server/3.7.14/rabbitmq-server-3.7.14.exe ).

Navigate to the sbin directory of the RabbitMQ installation.

Open a command line and enable the management plugin:

rabbitmq-plugins enable rabbitmq_management

Visit http://localhost:15672/ and log in with username guest and password guest.

Dynamic Configuration Refresh

Dynamic refresh requires Spring Cloud Config. The example uses the config‑server and config‑client modules from the previous lesson.

Add Bus Support to config‑server

Add dependencies to pom.xml:

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

Create application-amqp.yml with RabbitMQ settings and expose the bus-refresh actuator endpoint.

server:
  port: 8904
spring:
  application:
    name: config-server
  cloud:
    config:
      server:
        git:
          uri: https://gitee.com/macrozheng/springcloud-config.git
          username: macro
          password: 123456
          clone-on-start: true
    rabbitmq:
      host: localhost
      port: 5672
      username: guest
      password: guest
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8001/eureka/
management:
  endpoints:
    web:
      exposure:
        include: 'bus-refresh'

Add Bus Support to config‑client

Add the same spring-cloud-starter-bus-amqp dependency to the client’s pom.xml.

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

Create two bootstrap files ( bootstrap-amqp1.yml and bootstrap-amqp2.yml) for two client instances with different ports.

server:
  port: 9004
spring:
  application:
    name: config-client
  cloud:
    config:
      profile: dev
      label: dev
      name: config
      discovery:
        enabled: true
        service-id: config-server
    rabbitmq:
      host: localhost
      port: 5672
      username: guest
      password: guest
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8001/eureka/
management:
  endpoints:
    web:
      exposure:
        include: 'refresh'

Demonstration

Start Eureka server, config‑server (using application-amqp.yml), and the two config‑clients.

In the RabbitMQ console, a springCloudBus exchange and three queues prefixed with springCloudBus.anonymous are created.

Modify config-dev.yml in the Git repository (change config.info value).

# before
config:
  info: "config info for dev(dev)"
# after
config:
  info: "update config info for dev(dev)"

Trigger a refresh for all services via http://localhost:8904/actuator/bus-refresh . The updated value appears when calling http://localhost:9004/configInfo and http://localhost:9005/configInfo: update config info for dev(dev) To refresh a specific instance, call http://localhost:8904/actuator/bus-refresh/{destination}, e.g.,

http://localhost:8904/actuator/bus-refresh/config-client:9004

.

Using WebHooks

Configure a Gitee webhook to invoke the bus‑refresh endpoint whenever code is pushed to the configuration repository, enabling automatic configuration updates.

Modules Used

springcloud-learning
├── eureka-server   // Eureka registration center
├── config-server   // Configuration center service
└── config-client   // Client services that fetch configuration

Project Source Code

https://github.com/macrozheng/springcloud-learning