From 1244fe4b4ae896310324b74ed2d40dc4ef775215 Mon Sep 17 00:00:00 2001
From: bsmahi <bs.mahi@gmail.com>
Date: Sat, 29 Nov 2025 15:31:39 +0530
Subject: [PATCH] Upgraded to Spring Boot 4.0.0, Spring Cloud 2025.1.0, and
 Java 25

---
 04.docker/01-step-by-step-changes/readme.md   | 53 +++++++++++++++----
 04.docker/api-gateway/pom.xml                 | 20 +++----
 04.docker/currency-conversion-service/pom.xml | 30 +++++------
 .../CurrencyConversionController.java         | 53 +++++++++++++------
 04.docker/currency-exchange-service/pom.xml   | 30 +++++------
 04.docker/naming-server/pom.xml               | 13 ++---
 6 files changed, 118 insertions(+), 81 deletions(-)

diff --git a/04.docker/01-step-by-step-changes/readme.md b/04.docker/01-step-by-step-changes/readme.md
index 2905a2e..7220602 100644
--- a/04.docker/01-step-by-step-changes/readme.md
+++ b/04.docker/01-step-by-step-changes/readme.md
@@ -199,21 +199,50 @@ Have a little bit of patience. Wait for 5-10 minutes if you do not see traces!
 ### Additional Changes For Spring Boot 3+
 
 pom.xml
+```xml
+<!-- Enables tracing of REST API calls made using Feign-->
+<dependency>
+    <groupId>io.github.openfeign</groupId>
+    <artifactId>feign-micrometer</artifactId>
+</dependency>
 ```
-		<!-- Enables tracing of REST API calls made using Feign-->
-		<dependency>
-			<groupId>io.github.openfeign</groupId>
-			<artifactId>feign-micrometer</artifactId>
-		</dependency>
+> Starting with **Spring Boot 4**, the recommended way to call external APIs is to use **RestClient**, as **RestTemplate** is planned for deprecation.
+
+Reference Link: https://spring.io/blog/2025/09/30/the-state-of-http-clients-in-spring#the-future-of-http-clients-in-spring
+
+To use **RestClient**, you need to add the **HTTP Client** starter in `start.spring.io`.
+
+Follow these steps:
+
+1. Open **start.spring.io**
+2. Click **Add Dependencies**
+3. Type `client` in the search box
+4. Select **HTTP Client** from the list
+
+```xml
+<dependency>
+  <groupId>org.springframework.boot</groupId>
+  <artifactId>spring-boot-starter-restclient</artifactId>
+</dependency>
 ```
 
 CurrencyConversionController.java
 ```
+// Enable for Spring Boot 3.0.x
+//@Configuration(proxyBeanMethods = false)
+//class RestTemplateConfiguration {
+//
+//    @Bean
+//    RestTemplate restTemplate(RestTemplateBuilder builder) {
+//        return builder.build();
+//    }
+//}
+
 @Configuration(proxyBeanMethods = false)
-class RestTemplateConfiguration {
-    
+class RestClientConfiguration {
+
     @Bean
-    RestTemplate restTemplate(RestTemplateBuilder builder) {
+    RestClient restClient(RestClient.Builder builder) {
         return builder.build();
     }
 }
@@ -224,8 +253,12 @@ public class CurrencyConversionController {
 	@Autowired
 	private CurrencyExchangeProxy proxy;
 	
-	@Autowired
-	private RestTemplate restTemplate;
+    // Uncomment for Spring Boot 3.0.x
+//	@Autowired
+//	private RestTemplate restTemplate;
+
+    @Autowired
+    private RestClient restClient;
 
 ```
 
diff --git a/04.docker/api-gateway/pom.xml b/04.docker/api-gateway/pom.xml
index 246f061..8bdf4c7 100644
--- a/04.docker/api-gateway/pom.xml
+++ b/04.docker/api-gateway/pom.xml
@@ -5,7 +5,7 @@
 	<parent>
 		<groupId>org.springframework.boot</groupId>
 		<artifactId>spring-boot-starter-parent</artifactId>
-		<version>3.5.0</version>
+		<version>4.0.0</version>
 		<relativePath/> <!-- lookup parent from repository -->
 	</parent>
 	<groupId>com.in28minutes.microservices</groupId>
@@ -15,8 +15,8 @@
 	<description>Demo project for Spring Boot</description>
 
 	<properties>
-		<java.version>21</java.version>
-		<spring-cloud.version>2025.0.0</spring-cloud.version>
+		<java.version>25</java.version>
+		<spring-cloud.version>2025.1.0</spring-cloud.version>
 	</properties>
 
 	<dependencies>
@@ -75,13 +75,17 @@
 	        <artifactId>opentelemetry-exporter-zipkin</artifactId>
 	    </dependency>
 
-
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-devtools</artifactId>
 			<scope>runtime</scope>
 			<optional>true</optional>
 		</dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-actuator-test</artifactId>
+            <scope>test</scope>
+        </dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-test</artifactId>
@@ -116,12 +120,4 @@
 		</plugins>
 	</build>
 
-	<repositories>
-		<repository>
-			<id>spring-milestones</id>
-			<name>Spring Milestones</name>
-			<url>https://repo.spring.io/milestone</url>
-		</repository>
-	</repositories>
-
 </project>
diff --git a/04.docker/currency-conversion-service/pom.xml b/04.docker/currency-conversion-service/pom.xml
index 6a9da91..24bdac2 100644
--- a/04.docker/currency-conversion-service/pom.xml
+++ b/04.docker/currency-conversion-service/pom.xml
@@ -5,7 +5,7 @@
 	<parent>
 		<groupId>org.springframework.boot</groupId>
 		<artifactId>spring-boot-starter-parent</artifactId>
-		<version>3.5.0</version>
+		<version>4.0.0</version>
 		<relativePath/> <!-- lookup parent from repository -->
 	</parent>
 	<groupId>com.in28minutes.microservices</groupId>
@@ -15,8 +15,8 @@
 	<description>Demo project for Spring Boot</description>
 
 	<properties>
-		<java.version>21</java.version>
-		<spring-cloud.version>2025.0.0</spring-cloud.version>
+		<java.version>25</java.version>
+		<spring-cloud.version>2025.1.0</spring-cloud.version>
 	</properties>
 
 	<dependencies>
@@ -26,7 +26,7 @@
 		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
-			<artifactId>spring-boot-starter-web</artifactId>
+			<artifactId>spring-boot-starter-webmvc</artifactId>
 		</dependency>
 <!-- 		<dependency>
 			<groupId>org.springframework.cloud</groupId>
@@ -93,11 +93,16 @@
 			<scope>runtime</scope>
 			<optional>true</optional>
 		</dependency>
-		<dependency>
-			<groupId>org.springframework.boot</groupId>
-			<artifactId>spring-boot-starter-test</artifactId>
-			<scope>test</scope>
-		</dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-actuator-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-webmvc-test</artifactId>
+            <scope>test</scope>
+        </dependency>
 	</dependencies>
 
 	<dependencyManagement>
@@ -127,12 +132,5 @@
 		</plugins>
 	</build>
 
-	<repositories>
-		<repository>
-			<id>spring-milestones</id>
-			<name>Spring Milestones</name>
-			<url>https://repo.spring.io/milestone</url>
-		</repository>
-	</repositories>
 
 </project>
diff --git a/04.docker/currency-conversion-service/src/main/java/com/in28minutes/microservices/currencyconversionservice/CurrencyConversionController.java b/04.docker/currency-conversion-service/src/main/java/com/in28minutes/microservices/currencyconversionservice/CurrencyConversionController.java
index 2116390..e13b522 100644
--- a/04.docker/currency-conversion-service/src/main/java/com/in28minutes/microservices/currencyconversionservice/CurrencyConversionController.java
+++ b/04.docker/currency-conversion-service/src/main/java/com/in28minutes/microservices/currencyconversionservice/CurrencyConversionController.java
@@ -13,11 +13,21 @@
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.client.RestTemplate;
 
+// Enable for Spring Boot 3.0.x
+//@Configuration(proxyBeanMethods = false)
+//class RestTemplateConfiguration {
+//
+//    @Bean
+//    RestTemplate restTemplate(RestTemplateBuilder builder) {
+//        return builder.build();
+//    }
+//}
+
 @Configuration(proxyBeanMethods = false)
-class RestTemplateConfiguration {
-    
+class RestClientConfiguration {
+
     @Bean
-    RestTemplate restTemplate(RestTemplateBuilder builder) {
+    RestClient restClient(RestClient.Builder builder) {
         return builder.build();
     }
 }
@@ -28,8 +38,12 @@ public class CurrencyConversionController {
 	@Autowired
 	private CurrencyExchangeProxy proxy;
 
-	@Autowired
-	private RestTemplate restTemplate;
+    // Uncomment for Spring Boot 3.0.x
+//	@Autowired
+//	private RestTemplate restTemplate;
+
+    @Autowired
+    private RestClient restClient;
 
 	@GetMapping("/currency-conversion/from/{from}/to/{to}/quantity/{quantity}")
 	public CurrencyConversion calculateCurrencyConversion(
@@ -41,18 +55,23 @@ public CurrencyConversion calculateCurrencyConversion(
 		HashMap<String, String> uriVariables = new HashMap<>();
 		uriVariables.put("from",from);
 		uriVariables.put("to",to);
-		
-		ResponseEntity<CurrencyConversion> responseEntity = restTemplate.getForEntity
-		("http://localhost:8000/currency-exchange/from/{from}/to/{to}", 
-				CurrencyConversion.class, uriVariables);
-		
-		CurrencyConversion currencyConversion = responseEntity.getBody();
-		
-		return new CurrencyConversion(currencyConversion.getId(), 
-				from, to, quantity, 
-				currencyConversion.getConversionMultiple(), 
-				quantity.multiply(currencyConversion.getConversionMultiple()), 
-				currencyConversion.getEnvironment()+ " " + "rest template");
+
+        //		ResponseEntity<CurrencyConversion> responseEntity = restTemplate.getForEntity
+//		("http://localhost:8000/currency-exchange/from/{from}/to/{to}",
+//				CurrencyConversion.class, uriVariables);
+
+        CurrencyConversion currencyConversion = restClient.get()
+                .uri("http://localhost:8000/currency-exchange/from/{from}/to/{to}", uriVariables)
+                .retrieve()
+                .body(CurrencyConversion.class);
+
+        // CurrencyConversion currencyConversion = responseEntity.getBody();
+
+        return new CurrencyConversion(currencyConversion.getId(),
+                from, to, quantity,
+                currencyConversion.getConversionMultiple(),
+                quantity.multiply(currencyConversion.getConversionMultiple()),
+                currencyConversion.getEnvironment()+ " " + "rest client");
 		
 	}
 
diff --git a/04.docker/currency-exchange-service/pom.xml b/04.docker/currency-exchange-service/pom.xml
index b0e8aad..4460c9b 100644
--- a/04.docker/currency-exchange-service/pom.xml
+++ b/04.docker/currency-exchange-service/pom.xml
@@ -5,7 +5,7 @@
 	<parent>
 		<groupId>org.springframework.boot</groupId>
 		<artifactId>spring-boot-starter-parent</artifactId>
-		<version>3.5.0</version>
+		<version>4.0.0</version>
 		<relativePath/> <!-- lookup parent from repository -->
 	</parent>
 	<groupId>com.in28minutes.microservices</groupId>
@@ -15,8 +15,8 @@
 	<description>Demo project for Spring Boot</description>
 
 	<properties>
-		<java.version>21</java.version>
-		<spring-cloud.version>2025.0.0</spring-cloud.version>
+		<java.version>25</java.version>
+		<spring-cloud.version>2025.1.0</spring-cloud.version>
 	</properties>
 
 	<dependencies>
@@ -27,7 +27,7 @@
 		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
-			<artifactId>spring-boot-starter-web</artifactId>
+			<artifactId>spring-boot-starter-webmvc</artifactId>
 		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
@@ -102,11 +102,16 @@
 			<scope>runtime</scope>
 			<optional>true</optional>
 		</dependency>
-		<dependency>
-			<groupId>org.springframework.boot</groupId>
-			<artifactId>spring-boot-starter-test</artifactId>
-			<scope>test</scope>
-		</dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-actuator-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-webmvc-test</artifactId>
+            <scope>test</scope>
+        </dependency>
 	</dependencies>
 
 	<dependencyManagement>
@@ -136,12 +141,5 @@
 		</plugins>
 	</build>
 
-	<repositories>
-		<repository>
-			<id>spring-milestones</id>
-			<name>Spring Milestones</name>
-			<url>https://repo.spring.io/milestone</url>
-		</repository>
-	</repositories>
 
 </project>
diff --git a/04.docker/naming-server/pom.xml b/04.docker/naming-server/pom.xml
index 5019173..6fa4571 100644
--- a/04.docker/naming-server/pom.xml
+++ b/04.docker/naming-server/pom.xml
@@ -5,7 +5,7 @@
 	<parent>
 		<groupId>org.springframework.boot</groupId>
 		<artifactId>spring-boot-starter-parent</artifactId>
-		<version>3.5.0</version>
+		<version>4.0.0</version>
 		<relativePath/> <!-- lookup parent from repository -->
 	</parent>
 	<groupId>com.in28minutes.microservices</groupId>
@@ -15,8 +15,8 @@
 	<description>Demo project for Spring Boot</description>
 
 	<properties>
-		<java.version>21</java.version>
-		<spring-cloud.version>2025.0.0</spring-cloud.version>
+		<java.version>25</java.version>
+		<spring-cloud.version>2025.1.0</spring-cloud.version>
 	</properties>
 
 	<dependencies>
@@ -75,12 +75,5 @@
 		</plugins>
 	</build>
 
-	<repositories>
-		<repository>
-			<id>spring-milestones</id>
-			<name>Spring Milestones</name>
-			<url>https://repo.spring.io/milestone</url>
-		</repository>
-	</repositories>
 
 </project>