Add spring-boot-microservices-project: config server, Eureka, gateway and three services on Boot 4.1.1 + Spring Cloud 2025.1.3

Product, order and inventory services behind Spring Cloud Gateway (WebMVC), configuration from a Config Server, discovery with Eureka, a Resilience4j circuit breaker on order -> inventory and Brave tracing. Run as six plain jars; output/ holds real transcripts (config, registry, requests, trace propagation, circuit breaker, startup race and the load-balanced RestClient.Builder trap). Dockerfile and docker-compose.yml are included but were not run. Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_01HhW8LD8r3EigoBaCGrQZx5
2026-10-21 17:08:42 +00:00
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+# spring-boot-microservices-project
+
+A small e-commerce system on **Spring Boot 4.1.1** and **Spring Cloud 2025.1.3**, written for the article
+[Spring Boot Microservices Project: Gateway, Discovery, Config and 3 Services](https://ankurm.com/spring-boot-microservices-project/).
+
+```
+client ──> gateway :8080 ──> product-service   :8081
+                         ├─> order-service     :8082 ──> product-service   (read the price)
+                         │                          └──> inventory-service (reserve stock, circuit breaker)
+                         └─> inventory-service :8083
+config-server :8888   serves every service's configuration (and the gateway's routes)
+discovery-server :8761  (Eureka) every service registers here and finds the others here
+```
+
+| Module | What it is |
+|---|---|
+| `config-server` | Spring Cloud Config Server, native profile; files in `src/main/resources/config/` |
+| `discovery-server` | Eureka server |
+| `gateway` | Spring Cloud Gateway Server WebMVC; routes come from the config server (`gateway.yml`) |
+| `product-service` | `GET /products`, `GET /products/{id}` |
+| `inventory-service` | stock levels, `POST /inventory/{id}/reserve`, a switch to simulate an outage |
+| `order-service` | `POST /orders`; calls product-service and inventory-service through the load balancer and a Resilience4j circuit breaker |
+
+## Run it (no Docker needed)
+
+Needs JDK 21+, Maven 3.9+, curl and python3.
+
+```bash
+./scripts/run-all.sh        # build, start the six services, run the scenarios, stop everything
+./scripts/start.sh          # or: start the services and leave them running
+./scripts/demo.sh           # re-run the scenarios (rewrites output/)
+./scripts/stop.sh
+```
+
+Start order matters: **config server first** (everything else reads its configuration from it), then Eureka, then the rest.
+
+## Docker
+
+`Dockerfile` and `docker-compose.yml` are provided but were **not run**: the sandbox this was written in had no Docker.
+Treat them as a starting point, not a tested artifact.
+
+## Captured output
+
+Every file in `output/` is written by `scripts/demo.sh` from real requests. Nothing is typed by hand.
+
+| File | What it shows |
+|---|---|
+| `01-config-server.txt` | What the config server serves and the value the order service ended up with |
+| `02-eureka-registry.txt` | The instances registered in Eureka |
+| `03-gateway-requests.txt` | Requests through the gateway: products, stock, orders, and the error cases |
+| `04-trace-propagation.txt` | One request, one trace id, in the logs of four services |
+| `05-circuit-breaker.txt` | The circuit breaker going CLOSED, OPEN, and back to CLOSED |
+
+## Versions
+
+Spring Boot 4.1.1, Spring Framework 7, Spring Cloud 2025.1.3 (its BOM is built against Boot 4.0.8; it ran here on 4.1.1),
+Tomcat 11, Java 21 (OpenJDK 21.0.12). JDK 25 was not available when this was written.