Spring Boot 2 actuator

pom.xml

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

application.properties

By default, only health,info,metrics are enabled.
To enable all others :

management.endpoints.web.exposure.include=*

Actuators

/beans : Displays a complete list of all the Spring beans in your application.
/cache : Exposes available caches.
/configprops : Displays a collated list of all @ConfigurationProperties.
/env : Exposes properties from Spring’s ConfigurableEnvironment.
/health : Shows application health information.
/httptrace : Displays HTTP trace information (by default, the last 100 HTTP request-response exchanges). Requires an HttpTraceRepository bean.
/loggers : Shows and modifies the configuration of loggers in the application.
/metrics : Shows ‘metrics’ information for the current application.
/mappings : Displays a collated list of all @RequestMapping paths.
/scheduledtasks : Displays the scheduled tasks in your application.
/threaddump : Performs a thread dump.

acess uri

/actuator/fooEndPoint

How to enable all actuators in Spring Boot 2.2+

Since Spring Boot 2.2, by default, some are disabled such as httptraces or shutdown. 
To enable all of them  :
management.endpoints.web.exposure.include=*
Warning : including all actuators is not enough for « protected » actuators that are disabled by default such as the shutdown actuator.

How to enable httptraces actuator in Spring Boot 2.2+

We need to include it or all (as seen above)  :
But we also need to register a httpTraceRepository bean :

import org.springframework.boot.actuate.trace.http.HttpTraceRepository;
import org.springframework.boot.actuate.trace.http.InMemoryHttpTraceRepository;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
 
@Configuration
public class HttpTraceActuatorConfiguration {
 
    @Bean
    public HttpTraceRepository httpTraceRepository() {
        return new InMemoryHttpTraceRepository();
    }
 
}

How to use the loggers actuator

To change dynamically a logger level (for a package or class) :
curl -v "http://foobar:8080/actuator/loggers/my.package.bar.MyClass" -H "Content-Type: application/json" -d $'{ "configuredLevel": "DEBUG" }'

The health actuator

By default, only the status (UP or not) of the app is rendered.
To get more information (especially the disk space), we could specify a property for that endpoint :
endpoint.health.show-details: always to display it for anybody.
endpoint.health.show-details: when_authorized to display it for users authorized for that actuator.

How to enable and use the shutdown actuator in Spring Boot 2.2+

We need to include it or all (as seen above) . 
But we also need to enable it :
management.endpoint.shutdown.enabled=true
Optionally we could set the shutdown type and the timeout before force resources shutdown :
Example :

server.shutdown: graceful # Type of shutdown that the server performs. Default immediate
spring.lifecycle.timeout-per-shutdown-phase: 40s # Timeout for the shutdown of any phase. Default 30s

How to use it ?
The actuator has to be called with a POST request such as :
curl -X POST "http://localhost:8090/actuator/shutdown"

Trace actuator

Identify all mappings :
curl "http://localhost:8888/actuator/mappings" | grep -P -o "\"patterns\":.*?]"

Disable security for actuator

public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
// ...
  @Override
  protected void configure(HttpSecurity http) throws Exception {
    http.authorizeRequests()
        .antMatchers("/actuator", "/actuator/*")
        .permitAll();
    // ...
   }
// ...
}