[BAEL-5110] Actuator endpoint for startup tracking (#11351)

spring-boot-modules/spring-boot-actuator/src/main/java/com/baeldung/startup/ResourceInitializer.java

@@ -0,0 +1,17 @@
+package com.baeldung.startup;
+
+import org.springframework.stereotype.Component;
+
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.TimeUnit;
+
+@Component
+public class ResourceInitializer {
+
+    ResourceInitializer() throws Exception {
+        // simulate resource init with random delay of a few seconds
+        int randomDelay = ThreadLocalRandom.current().nextInt(5, 9);
+        TimeUnit.SECONDS.sleep(randomDelay);
+    }
+
+}

spring-boot-modules/spring-boot-actuator/src/main/java/com/baeldung/startup/StartupTrackingApplication.java

@@ -0,0 +1,38 @@
+package com.baeldung.startup;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.actuate.autoconfigure.security.servlet.ManagementWebSecurityAutoConfiguration;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration;
+import org.springframework.boot.context.metrics.buffering.BufferingApplicationStartup;
+
+import static java.lang.Boolean.FALSE;
+
+@SpringBootApplication(exclude = {
+  SecurityAutoConfiguration.class,
+  ManagementWebSecurityAutoConfiguration.class}
+)
+public class StartupTrackingApplication {
+
+    public static void main(String[] args) {
+        // only load properties for this application
+        System.setProperty("spring.config.location", "classpath:application-startup.properties");
+
+        SpringApplication app = new SpringApplication(StartupTrackingApplication.class);
+        BufferingApplicationStartup startup = new BufferingApplicationStartup(2048);
+
+        if (shouldFilterSteps()) {
+            startup.addFilter(startupStep -> startupStep.getName().matches("spring.beans.instantiate"));
+        }
+
+        app.setApplicationStartup(startup);
+        app.run(args);
+    }
+
+    private static boolean shouldFilterSteps() {
+        return Boolean.parseBoolean(
+          System.getProperty("startup.steps.filter", FALSE.toString())
+        );
+    }
+
+}

spring-boot-modules/spring-boot-actuator/src/main/resources/application-startup.properties

@@ -0,0 +1,6 @@
+management.endpoints.web.exposure.include=startup
+
+# JPA is not required for startup actuator endpoint
+spring.autoconfigure.exclude= org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration, \
+  org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration, \
+  org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration