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Spring Cloud Config Client

What is a Config Client?

A Config Client is a microservice that connects to the Spring Cloud Config Server to fetch the applications configuration at startup.This ensures all services load centralized configuration stored in a remote repository (e.g., Git).

Steps to Configure a Spring Cloud Config Client

1. Add Config Client Dependency 

<!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-config-client -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-config-client</artifactId>
    <version>4.3.0</version>
</dependency>

2. Add Config Server URL in microservice

In application.properties (or YAML):

spring.config.import=optional:configserver:http://myhost:8888

On Startup — Logs Example

INFO  --- ConfigServerConfigDataLoader : Fetching config from server at : http://localhost:8888
INFO  --- ConfigServerConfigDataLoader : Located environment: name=user-service, profiles=[default]
This indicates the microservice successfully contacted the Config Server and loaded configuration.

Question

1. Profile-Based Configuration

Rules :

  • For dev profile create application-dev.properties
  • For prod profile create application-prod.properties

1.1 If have multiple profile configuation file then how Configuration work?

suppose user-service uses a profile such as dev: spring.profiles.active=dev The Config Server loads from application.propertiesand application-dev.properties

Log Example
The following 1 profile is active: "dev"
Fetching config from server at : http://localhost:8888
Located environment: name=user-service, profiles=[default]
Fetching config from server at : http://localhost:8888
Located environment: name=user-service, profiles=[dev]

2. How to Configure Data for a Specific Microservice with profile based ?

Location File
create config file of specific profile application-dev.properties , applicaiton-prod.properties
create config file of specific microservice user-service.properties , order-service.properties
create config file of specific microservice and profile user-service-dev.properties

3. Port Override Example

suppose for user microservice has active profile dev and

Location Port
Local application.properties 8081
Config Server application.properties 8082
Config Server application-dev.properties 8083
Config Server user-service.properties 8084
Config Server user-service-dev.properties 8085

Then,

Final Port Used : 8085 Because service-specific + dev config file has the highest priority.

4. suppose user-service has dev profile then how will configuration data ?

If user-service has the dev profile active, Spring Cloud Config will load configuration files in a specific priority order.Only dev configs are considered.

Load Order (Top = Highest Priority) File
1 user-service-dev.properties (service + profile specific)
2 user-service.properties (service specific)
3 application-dev.properties (global profile config)
4 application.properties (global default config)

5. Real-World Configuration Scenario

  • Case :

    • Out of 10 microservices, 7 microservices share a property
    • 3 microservices need a different value

  • Solution:

    • Put the common property in application.properties (config server) : app.owner=alamgir

    • Override only for required services in their individual files service-specific override: service1.properties → app.owner=service1 service2.properties → app.owner=service2 service3.properties → app.owner=service3