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
commit def73fa1c4
49 changed files with 1419 additions and 0 deletions
@@ -0,0 +1,47 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <groupId>com.ankurm.shop</groupId>
+    <artifactId>shop</artifactId>
+    <version>1.0.0</version>
+  </parent>
+  <artifactId>inventory-service</artifactId>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter-webmvc</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter-actuator</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.springframework.cloud</groupId>
+      <artifactId>spring-cloud-starter-config</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.springframework.cloud</groupId>
+      <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-micrometer-tracing-brave</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>io.micrometer</groupId>
+      <artifactId>micrometer-tracing-bridge-brave</artifactId>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-maven-plugin</artifactId>
+      </plugin>
+    </plugins>
+  </build>
+</project>
@@ -0,0 +1,86 @@
+package com.ankurm.shop.inventory;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.server.ResponseStatusException;
+
+@RestController
+class InventoryController {
+    private static final Logger log = LoggerFactory.getLogger(InventoryController.class);
+
+    record ReserveRequest(int quantity) {
+    }
+
+    private final InventoryProperties properties;
+    private final Map<Long, AtomicInteger> stock = new ConcurrentHashMap<>(Map.of(
+            1L, new AtomicInteger(20), 2L, new AtomicInteger(8), 3L, new AtomicInteger(3)));
+    private final AtomicBoolean down = new AtomicBoolean(false);
+    private final AtomicInteger reserveCalls = new AtomicInteger();
+
+    InventoryController(InventoryProperties properties) {
+        this.properties = properties;
+    }
+
+    @GetMapping("/inventory/{productId}")
+    Map<String, Object> level(@PathVariable long productId) {
+        AtomicInteger s = stock.get(productId);
+        if (s == null) {
+            throw new ResponseStatusException(HttpStatus.NOT_FOUND, "No stock record for product " + productId);
+        }
+        return view(productId, s.get());
+    }
+
+    @PostMapping("/inventory/{productId}/reserve")
+    Map<String, Object> reserve(@PathVariable long productId, @RequestBody ReserveRequest request) {
+        reserveCalls.incrementAndGet();
+        if (down.get()) {
+            log.warn("simulating an outage: refusing to reserve product {}", productId);
+            throw new ResponseStatusException(HttpStatus.SERVICE_UNAVAILABLE, "inventory is down");
+        }
+        AtomicInteger s = stock.get(productId);
+        if (s == null) {
+            throw new ResponseStatusException(HttpStatus.NOT_FOUND, "No stock record for product " + productId);
+        }
+        int remaining = s.addAndGet(-request.quantity());
+        if (remaining < 0) {
+            s.addAndGet(request.quantity());
+            throw new ResponseStatusException(HttpStatus.CONFLICT, "Only " + s.get() + " of product " + productId + " in stock");
+        }
+        log.info("reserved {} of product {}, {} left", request.quantity(), productId, remaining);
+        return view(productId, remaining);
+    }
+
+    /** Test switch: POST /inventory/chaos?down=true makes every reserve call fail with 503. */
+    @PostMapping("/inventory/chaos")
+    Map<String, Object> chaos(@RequestParam boolean down) {
+        this.down.set(down);
+        log.info("outage simulation is now {}", down ? "ON" : "OFF");
+        return Map.of("down", down);
+    }
+
+    /** How many reserve calls actually reached this service (a circuit-breaker test needs this). */
+    @GetMapping("/inventory/stats")
+    Map<String, Object> stats() {
+        return Map.of("reserveCalls", reserveCalls.get());
+    }
+
+    private Map<String, Object> view(long productId, int quantity) {
+        Map<String, Object> m = new LinkedHashMap<>();
+        m.put("productId", productId);
+        m.put("quantity", quantity);
+        m.put("lowStock", quantity <= properties.lowStockThreshold());
+        return m;
+    }
+}
@@ -0,0 +1,8 @@
+package com.ankurm.shop.inventory;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+
+/** Bound from shop.inventory.* , which comes from the config server (inventory-service.yml). */
+@ConfigurationProperties("shop.inventory")
+record InventoryProperties(int lowStockThreshold) {
+}
@@ -0,0 +1,13 @@
+package com.ankurm.shop.inventory;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.context.properties.ConfigurationPropertiesScan;
+
+@SpringBootApplication
+@ConfigurationPropertiesScan
+public class InventoryServiceApplication {
+    public static void main(String[] args) {
+        SpringApplication.run(InventoryServiceApplication.class, args);
+    }
+}
@@ -0,0 +1,16 @@
+spring:
+  application:
+    name: inventory-service
+  config:
+    # Fail fast if the config server is not up: a service with the wrong config is worse than no service.
+    import: "configserver:${CONFIG_URL:http://localhost:8888}"
+server:
+  port: 8083
+eureka:
+  client:
+    service-url:
+      defaultZone: ${EUREKA_URL:http://localhost:8761/eureka}
+  instance:
+    hostname: ${EUREKA_HOSTNAME:localhost}
+    # Register the service name + port as the instance id so two copies of one service do not collide.
+    instance-id: ${spring.application.name}:${server.port}