feat: Spring Boot 4 support

.editorconfig

@@ -23,7 +23,7 @@ ij_java_blank_lines_after_class_header = 0
 ij_java_doc_enable_formatting = false
 ij_java_class_count_to_use_import_on_demand = 100
 ij_java_names_count_to_use_import_on_demand = 100
-ij_java_imports_layout = |, java.**, |, jakarta.**, *, |, de.codecentric.boot.admin.**, |, $*
+ij_java_imports_layout = |, java.**, |, jakarta.**, *, tools.**, |, de.codecentric.boot.admin.**, |, $*
 ij_java_layout_static_imports_separately = true
 
 [*.xml]

.gitignore

@@ -28,3 +28,4 @@ node/
 
 .DS_Store
 mockServiceWorker.js
+/.github/agents/

pom.xml

@@ -30,7 +30,7 @@
     <url>https://github.com/codecentric/spring-boot-admin/</url>
 
     <properties>
-        <revision>3.5.8-SNAPSHOT</revision>
+        <revision>4.0.0-SNAPSHOT</revision>
 
         <java.version>17</java.version>
         <node.version>v22.12.0</node.version>
@@ -47,18 +47,18 @@
         <maven.site.skip>true</maven.site.skip>
 
         <!-- used dependencies versions -->
-        <spring-boot.version>3.5.10</spring-boot.version>
-        <spring-cloud.version>2025.0.0</spring-cloud.version>
+        <spring-boot.version>4.0.2</spring-boot.version>
+        <spring-cloud.version>2025.1.1</spring-cloud.version>
 
-        <jolokia-support-spring.version>2.4.3</jolokia-support-spring.version>
+        <!-- FIXME downgrade to 2.1.0 until a compatible version is released -->
+        <jolokia-support-spring.version>2.1.0</jolokia-support-spring.version>
 
         <checkstyle.version>12.3.1</checkstyle.version>
         <findbugs-jsr305.version>3.0.2</findbugs-jsr305.version>
 
         <wiremock.version>3.13.2</wiremock.version>
         <hazelcast.version>5.6.0</hazelcast.version>
         <awaitility.version>4.3.0</awaitility.version>
-        <testcontainers.version>2.0.3</testcontainers.version>
         <jetty.version>12.1.6</jetty.version>
 
         <!-- plugin versions -->

spring-boot-admin-build/pom.xml

@@ -85,18 +85,6 @@
                 <version>${awaitility.version}</version>
                 <scope>test</scope>
             </dependency>
-            <dependency>
-                <groupId>org.testcontainers</groupId>
-                <artifactId>testcontainers</artifactId>
-                <version>${testcontainers.version}</version>
-                <scope>test</scope>
-            </dependency>
-            <dependency>
-                <groupId>org.testcontainers</groupId>
-                <artifactId>testcontainers-junit-jupiter</artifactId>
-                <version>${testcontainers.version}</version>
-                <scope>test</scope>
-            </dependency>
         </dependencies>
     </dependencyManagement>
 

spring-boot-admin-client/pom.xml

@@ -41,27 +41,27 @@
             <artifactId>spring-boot-starter-actuator</artifactId>
         </dependency>
         <dependency>
-            <groupId>org.springframework</groupId>
-            <artifactId>spring-web</artifactId>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-restclient</artifactId>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
-            <artifactId>spring-boot-starter-web</artifactId>
+            <artifactId>spring-boot-starter-webflux</artifactId>
             <optional>true</optional>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
-            <artifactId>spring-boot-autoconfigure-processor</artifactId>
+            <artifactId>spring-boot-starter-webmvc</artifactId>
             <optional>true</optional>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
-            <artifactId>spring-boot-configuration-processor</artifactId>
+            <artifactId>spring-boot-autoconfigure-processor</artifactId>
             <optional>true</optional>
         </dependency>
         <dependency>
-            <groupId>org.springframework</groupId>
-            <artifactId>spring-webflux</artifactId>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-configuration-processor</artifactId>
             <optional>true</optional>
         </dependency>
         <dependency>
@@ -74,11 +74,6 @@
             <artifactId>spring-boot-starter-test</artifactId>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>org.springframework.boot</groupId>
-            <artifactId>spring-boot-starter-webflux</artifactId>
-            <scope>test</scope>
-        </dependency>
         <dependency>
             <groupId>org.wiremock</groupId>
             <artifactId>wiremock-standalone</artifactId>

spring-boot-admin-client/src/main/java/de/codecentric/boot/admin/client/config/ClientProperties.java

@@ -19,11 +19,11 @@
 import java.time.Duration;
 import java.time.temporal.ChronoUnit;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.boot.cloud.CloudPlatform;
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.convert.DurationUnit;
 import org.springframework.core.env.Environment;
-import org.springframework.lang.Nullable;
 
 @lombok.Data
 @ConfigurationProperties(prefix = "spring.boot.admin.client")
@@ -60,21 +60,18 @@ public class ClientProperties {
 	/**
 	 * Username for basic authentication on admin server
 	 */
-	@Nullable
-	private String username;
+	@Nullable private String username;
 
 	/**
 	 * Password for basic authentication on admin server
 	 */
-	@Nullable
-	private String password;
+	@Nullable private String password;
 
 	/**
 	 * Enable automatic deregistration on shutdown If not set it defaults to true if an
 	 * active {@link CloudPlatform} is present;
 	 */
-	@Nullable
-	private Boolean autoDeregistration = null;
+	@Nullable private Boolean autoDeregistration = null;
 
 	/**
 	 * Enable automatic registration when the application is ready.

spring-boot-admin-client/src/main/java/de/codecentric/boot/admin/client/config/ClientRuntimeHints.java

@@ -21,7 +21,7 @@
 import org.springframework.aot.hint.MemberCategory;
 import org.springframework.aot.hint.RuntimeHints;
 import org.springframework.aot.hint.RuntimeHintsRegistrar;
-import org.springframework.boot.web.context.WebServerInitializedEvent;
+import org.springframework.boot.web.server.context.WebServerInitializedEvent;
 import org.springframework.context.annotation.Configuration;
 
 import de.codecentric.boot.admin.client.registration.Application;

spring-boot-admin-client/src/main/java/de/codecentric/boot/admin/client/config/CloudFoundryApplicationProperties.java

@@ -19,18 +19,16 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.boot.context.properties.ConfigurationProperties;
-import org.springframework.lang.Nullable;
 
 @lombok.Data
 @ConfigurationProperties("vcap.application")
 public class CloudFoundryApplicationProperties {
 
-	@Nullable
-	private String applicationId;
+	@Nullable private String applicationId;
 
-	@Nullable
-	private String instanceIndex;
+	@Nullable private String instanceIndex;
 
 	private List<String> uris = new ArrayList<>();
 

spring-boot-admin-client/src/main/java/de/codecentric/boot/admin/client/config/InstanceProperties.java

@@ -19,9 +19,9 @@
 import java.util.LinkedHashMap;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.boot.context.properties.ConfigurationProperties;
-import org.springframework.lang.Nullable;
 
 @lombok.Data
 @ConfigurationProperties(prefix = "spring.boot.admin.client.instance")
@@ -31,43 +31,37 @@ public class InstanceProperties {
 	 * Management-url to register with. Inferred at runtime, can be overridden in case the
 	 * reachable URL is different (e.g. Docker).
 	 */
-	@Nullable
-	private String managementUrl;
+	@Nullable private String managementUrl;
 
 	/**
 	 * Base url for computing the management-url to register with. The path is inferred at
 	 * runtime, and appended to the base url.
 	 */
-	@Nullable
-	private String managementBaseUrl;
+	@Nullable private String managementBaseUrl;
 
 	/**
 	 * Client-service-URL register with. Inferred at runtime, can be overridden in case
 	 * the reachable URL is different (e.g. Docker).
 	 */
-	@Nullable
-	private String serviceUrl;
+	@Nullable private String serviceUrl;
 
 	/**
 	 * Base url for computing the service-url to register with. The path is inferred at
 	 * runtime, and appended to the base url.
 	 */
-	@Nullable
-	private String serviceBaseUrl;
+	@Nullable private String serviceBaseUrl;
 
 	/**
 	 * Path for computing the service-url to register with. If not specified, defaults to
 	 * "/"
 	 */
-	@Nullable
-	private String servicePath;
+	@Nullable private String servicePath;
 
 	/**
 	 * Client-health-URL to register with. Inferred at runtime, can be overridden in case
 	 * the reachable URL is different (e.g. Docker). Must be unique all services registry.
 	 */
-	@Nullable
-	private String healthUrl;
+	@Nullable private String healthUrl;
 
 	/**
 	 * Name to register with. Defaults to ${spring.application.name}

spring-boot-admin-client/src/main/java/de/codecentric/boot/admin/client/config/SpringBootAdminClientAutoConfiguration.java

@@ -29,33 +29,29 @@
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
-import org.springframework.boot.autoconfigure.web.ServerProperties;
-import org.springframework.boot.autoconfigure.web.client.RestClientAutoConfiguration;
-import org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration;
-import org.springframework.boot.autoconfigure.web.reactive.WebFluxProperties;
-import org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration;
-import org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration;
-import org.springframework.boot.autoconfigure.web.servlet.DispatcherServletPath;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication.Type;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.boot.http.client.ClientHttpRequestFactoryBuilder;
-import org.springframework.boot.http.client.ClientHttpRequestFactorySettings;
-import org.springframework.boot.web.client.RestTemplateBuilder;
+import org.springframework.boot.http.client.HttpClientSettings;
+import org.springframework.boot.restclient.autoconfigure.RestClientAutoConfiguration;
+import org.springframework.boot.web.server.autoconfigure.ServerProperties;
+import org.springframework.boot.webflux.autoconfigure.WebFluxProperties;
+import org.springframework.boot.webmvc.autoconfigure.DispatcherServletAutoConfiguration;
+import org.springframework.boot.webmvc.autoconfigure.DispatcherServletPath;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Lazy;
 import org.springframework.core.env.Environment;
 import org.springframework.http.client.support.BasicAuthenticationInterceptor;
+import org.springframework.http.converter.json.JacksonJsonHttpMessageConverter;
 import org.springframework.web.client.RestClient;
-import org.springframework.web.client.RestTemplate;
-import org.springframework.web.reactive.function.client.WebClient;
+import tools.jackson.databind.json.JsonMapper;
 
 import de.codecentric.boot.admin.client.registration.ApplicationFactory;
 import de.codecentric.boot.admin.client.registration.ApplicationRegistrator;
-import de.codecentric.boot.admin.client.registration.BlockingRegistrationClient;
 import de.codecentric.boot.admin.client.registration.DefaultApplicationRegistrator;
 import de.codecentric.boot.admin.client.registration.ReactiveApplicationFactory;
-import de.codecentric.boot.admin.client.registration.ReactiveRegistrationClient;
 import de.codecentric.boot.admin.client.registration.RegistrationApplicationListener;
 import de.codecentric.boot.admin.client.registration.RegistrationClient;
 import de.codecentric.boot.admin.client.registration.RestClientRegistrationClient;
@@ -64,14 +60,10 @@
 import de.codecentric.boot.admin.client.registration.metadata.MetadataContributor;
 import de.codecentric.boot.admin.client.registration.metadata.StartupDateMetadataContributor;
 
-import static org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication.Type;
-import static org.springframework.web.reactive.function.client.ExchangeFilterFunctions.basicAuthentication;
-
 @Configuration(proxyBeanMethods = false)
 @ConditionalOnWebApplication
 @Conditional(SpringBootAdminClientEnabledCondition.class)
-@AutoConfigureAfter({ WebEndpointAutoConfiguration.class, RestClientAutoConfiguration.class,
-		RestTemplateAutoConfiguration.class, WebClientAutoConfiguration.class })
+@AutoConfigureAfter({ WebEndpointAutoConfiguration.class, RestClientAutoConfiguration.class })
 @EnableConfigurationProperties({ ClientProperties.class, InstanceProperties.class, ServerProperties.class,
 		ManagementServerProperties.class })
 public class SpringBootAdminClientAutoConfiguration {
@@ -139,59 +131,33 @@ public ApplicationFactory applicationFactory(InstanceProperties instance, Manage
 	}
 
 	@Configuration(proxyBeanMethods = false)
-	@ConditionalOnBean(RestTemplateBuilder.class)
-	public static class BlockingRegistrationClientConfig {
-
-		@Bean
-		@ConditionalOnMissingBean
-		public RegistrationClient registrationClient(ClientProperties client) {
-			RestTemplateBuilder builder = new RestTemplateBuilder().connectTimeout(client.getConnectTimeout())
-				.readTimeout(client.getReadTimeout());
-
-			if (client.getUsername() != null && client.getPassword() != null) {
-				builder = builder.basicAuthentication(client.getUsername(), client.getPassword());
-			}
-
-			RestTemplate build = builder.build();
-			return new BlockingRegistrationClient(build);
-		}
-
-	}
-
-	@Configuration(proxyBeanMethods = false)
-	@ConditionalOnBean({ RestClient.Builder.class, ClientHttpRequestFactoryBuilder.class })
+	@ConditionalOnBean(RestClient.Builder.class)
 	public static class RestClientRegistrationClientConfig {
 
 		@Bean
 		@ConditionalOnMissingBean
 		public RegistrationClient registrationClient(ClientProperties client, RestClient.Builder restClientBuilder,
-				ClientHttpRequestFactoryBuilder<?> clientHttpRequestFactoryBuilder) {
-			var factorySettings = ClientHttpRequestFactorySettings.defaults()
+				ObjectProvider<JsonMapper> objectMapper) {
+			var factorySettings = HttpClientSettings.defaults()
 				.withConnectTimeout(client.getConnectTimeout())
 				.withReadTimeout(client.getReadTimeout());
-			var clientHttpRequestFactory = clientHttpRequestFactoryBuilder.build(factorySettings);
-			restClientBuilder = restClientBuilder.requestFactory(clientHttpRequestFactory);
-			if (client.getUsername() != null && client.getPassword() != null) {
-				restClientBuilder = restClientBuilder
-					.requestInterceptor(new BasicAuthenticationInterceptor(client.getUsername(), client.getPassword()));
-			}
-			var restClient = restClientBuilder.build();
-			return new RestClientRegistrationClient(restClient);
-		}
 
-	}
+			var clientHttpRequestFactory = ClientHttpRequestFactoryBuilder.detect().build(factorySettings);
 
-	@Configuration(proxyBeanMethods = false)
-	@ConditionalOnBean(WebClient.Builder.class)
-	public static class ReactiveRegistrationClientConfig {
+			restClientBuilder.requestFactory(clientHttpRequestFactory);
+
+			objectMapper.ifAvailable((mapper) -> restClientBuilder.messageConverters((configurer) -> {
+				configurer.removeIf(JacksonJsonHttpMessageConverter.class::isInstance);
+				configurer.add(new JacksonJsonHttpMessageConverter(mapper));
+			}));
 
-		@Bean
-		@ConditionalOnMissingBean
-		public RegistrationClient registrationClient(ClientProperties client, WebClient.Builder webClient) {
 			if (client.getUsername() != null && client.getPassword() != null) {
-				webClient = webClient.filter(basicAuthentication(client.getUsername(), client.getPassword()));
+				restClientBuilder
+					.requestInterceptor(new BasicAuthenticationInterceptor(client.getUsername(), client.getPassword()));
 			}
-			return new ReactiveRegistrationClient(webClient.build(), client.getReadTimeout());
+
+			var restClient = restClientBuilder.build();
+			return new RestClientRegistrationClient(restClient);
 		}
 
 	}

spring-boot-admin-client/src/main/java/de/codecentric/boot/admin/client/config/SpringBootAdminClientCloudFoundryAutoConfiguration.java

@@ -27,9 +27,9 @@
 import org.springframework.boot.autoconfigure.condition.ConditionalOnCloudPlatform;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
-import org.springframework.boot.autoconfigure.web.ServerProperties;
 import org.springframework.boot.cloud.CloudPlatform;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.boot.web.server.autoconfigure.ServerProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;