Config Clients and Profiles

Add spring-cloud-starter-config to order-service and import the server in its own small application.yml:

spring:
  application:
    name: order-service        # decides which files are fetched
  profiles:
    active: ${SPRING_PROFILES_ACTIVE:dev}
  config:
    import: "optional:configserver:${CONFIG_SERVER_URL:http://localhost:8888}"
  cloud:
    config:
      fail-fast: false          # true in prod: refuse to start without config

SPRING_PROFILES_ACTIVE=prod java -jar order-service.jar

INFO  o.s.c.c.c.ConfigServerConfigDataLoader : Fetching config from server at : http://localhost:8888
INFO  o.s.c.c.c.ConfigServerConfigDataLoader : Located environment: name=order-service, profiles=[prod], label=null, version=4c1e9a7d, state=null
INFO  c.s.order.OrderServiceApplication       : The following 1 profile is active: "prod"

More specific sources override less specific ones. For order-service with profile prod, from weakest to strongest: local application.yml → repo application.yml → order-service.yml → order-service-prod.yml. This plain-Java program merges layers the same way and shows where each final value came from:

import java.util.*;

public class Main {
    public static void main(String[] args) {
        // weakest first
        List<Layer> layers = List.of(
            new Layer("local application.yml", Map.of(
                "server.port", "8082", "shopease.orders.max-items-per-order", "20")),
            new Layer("repo application.yml", Map.of(
                "management.endpoints.web.exposure.include", "health,info,refresh")),
            new Layer("repo order-service.yml", Map.of(
                "shopease.orders.max-items-per-order", "10", "shopease.orders.cod-enabled", "true")),
            new Layer("repo order-service-prod.yml", Map.of(
                "shopease.orders.max-items-per-order", "5"))
        );

        Map<String, String> value = new TreeMap<>();
        Map<String, String> source = new TreeMap<>();
        for (Layer layer : layers) {
            layer.props().forEach((k, v) -> {
                value.put(k, v);           // later layer overrides
                source.put(k, layer.name());
            });
        }
        value.forEach((k, v) ->
            System.out.printf("%-42s = %-20s <- %s%n", k, v, source.get(k)));
    }
}

record Layer(String name, Map<String, String> props) {}

management.endpoints.web.exposure.include  = health,info,refresh  <- repo application.yml
server.port                                = 8082                 <- local application.yml
shopease.orders.cod-enabled                = true                 <- repo order-service.yml
shopease.orders.max-items-per-order        = 5                    <- repo order-service-prod.yml

Prefer a typed @ConfigurationProperties record over many @Value fields (the Spring Boot material covers this in depth):

@ConfigurationProperties(prefix = "shopease.orders")
public record OrderProperties(int maxItemsPerOrder, boolean codEnabled) {}

@SpringBootApplication
@ConfigurationPropertiesScan
public class OrderServiceApplication { /* main */ }

@Service
@RequiredArgsConstructor
class OrderRules {
    private final OrderProperties props;

    void check(PlaceOrderRequest req) {
        if (req.items().size() > props.maxItemsPerOrder()) {
            throw new TooManyItemsException(props.maxItemsPerOrder());
        }
        if (req.paymentMode() == PaymentMode.COD && !props.codEnabled()) {
            throw new CodNotAvailableException();
        }
    }
}