BAEL-6179: Add Actuator sample without Spring Boot (#14032)

* BAEL-6179: Add Actuator sample without Spring Boot

* BAEL-6179: Simplify custom health indicator

spring-actuator/src/main/java/com/baeldung/spring/actuator/ActuatorConfiguration.java

@@ -0,0 +1,26 @@
+package com.baeldung.spring.actuator;
+
+import org.springframework.boot.actuate.health.Health;
+import org.springframework.boot.actuate.health.HealthIndicator;
+import org.springframework.boot.actuate.info.InfoContributor;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class ActuatorConfiguration {
+
+    @Bean
+    public HealthIndicator sampleHealthIndicator() {
+        return Health.up()
+          .withDetail("info", "Sample Health")
+          ::build;
+    }
+
+    @Bean
+    public InfoContributor provideSampleInfos() {
+        return builder ->
+          builder
+            .withDetail("app-title", "Actuator Sample Application");
+
+    }
+}

spring-actuator/src/main/java/com/baeldung/spring/actuator/AppConfig.java

@@ -0,0 +1,11 @@
+package com.baeldung.spring.actuator;
+
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.PropertySource;
+
+@EnableAutoConfiguration
+@PropertySource("classpath:application.properties")
+@ComponentScan(basePackageClasses = AppConfig.class)
+public class AppConfig {
+}

spring-actuator/src/main/java/com/baeldung/spring/actuator/Start.java

@@ -0,0 +1,64 @@
+package com.baeldung.spring.actuator;
+
+import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.servlet.ServletContextHandler;
+import org.eclipse.jetty.servlet.ServletHolder;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.web.context.ContextLoaderListener;
+import org.springframework.web.context.WebApplicationContext;
+import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
+import org.springframework.web.servlet.DispatcherServlet;
+
+public class Start {
+
+    private static final Logger logger = LoggerFactory.getLogger(Start.class);
+    private static final int DEFAULT_PORT = 8080;
+    private static final String CONTEXT_PATH = "/";
+    private static final String CONFIG_LOCATION = AppConfig.class.getName();
+    private static final String MAPPING_URL = "/*";
+
+    /*
+     * This application runs a Jetty webcontainer that runs the
+     * Spring Dispatcher Servlet.
+     */
+    public static void main(String[] args) throws Exception {
+        new Start().startJetty(getPortFromArgs(args));
+    }
+
+    private static int getPortFromArgs(String[] args) {
+        if (args.length > 0) {
+            try {
+                return Integer.parseInt(args[0]);
+            } catch (NumberFormatException ignore) {
+            }
+        }
+        logger.info("No server port configured, falling back to {}", DEFAULT_PORT);
+        return DEFAULT_PORT;
+    }
+
+    private void startJetty(int port) throws Exception {
+        logger.info("Starting server at port {}", port);
+        Server server = new Server(port);
+        server.setHandler(getServletContextHandler(getContext()));
+        server.start();
+        logger.info("Server started at port {}", port);
+        server.join();
+    }
+
+    private static ServletContextHandler getServletContextHandler(WebApplicationContext context) {
+        ServletContextHandler contextHandler = new ServletContextHandler();
+        contextHandler.setErrorHandler(null);
+        contextHandler.setContextPath(CONTEXT_PATH);
+        contextHandler.addServlet(new ServletHolder(new DispatcherServlet(context)), MAPPING_URL);
+        contextHandler.addEventListener(new ContextLoaderListener(context));
+        return contextHandler;
+    }
+
+    private static WebApplicationContext getContext() {
+        AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
+        context.setConfigLocation(CONFIG_LOCATION);
+        return context;
+    }
+
+}

spring-actuator/src/main/java/com/baeldung/spring/actuator/WebMvcConfiguration.java

@@ -0,0 +1,23 @@
+package com.baeldung.spring.actuator;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+
+@Configuration
+public class WebMvcConfiguration {
+
+    @Bean
+    public WebMvcConfigurer webMvcConfigurer() {
+        return new WebMvcConfigurer() {
+            @Override
+            public void addViewControllers(ViewControllerRegistry registry) {
+                registry
+                  .addViewController("/")
+                  .setViewName("redirect:/actuator");
+            }
+        };
+    }
+
+}

spring-actuator/src/main/resources/application.properties

@@ -0,0 +1,2 @@
+management.endpoints.web.exposure.include=*
+management.endpoint.health.show-details=always