The document discusses Spring Boot Actuator, a module that allows monitoring and management of Spring Boot applications. It describes the various endpoints exposed by Actuator for tasks like health checks, metrics collection, and accessing bean configuration details. It also covers how to write custom endpoints and leverage existing endpoint functionality through extensions. The document provides examples of annotations used to build endpoints and operations along with HTTP request formats.

1. Mastering Spring Boot’s Actuator
Madhura Bhave
@madhurabhave23

2. 2
Actuator?

3. 3
actuator
noun
mechanical device for moving or
controlling something
Spring Boot Actuator
noun
module for controlling Spring
Boot applications
Actuator?

4. Spring Boot Actuator Endpoints

5. Actuator endpoints
• Endpoints under /actuator
• management.endpoints.web.base-path
• management.endpoints.web.exposure.include
management.endpoints.web.exposure.exclude
• management.endpoint.shutdown.enabled
• management.endpoint.health.show-details
• EndpointRequest
• Jersey, WebFlux, or Spring MVC
5

6. 6
{
"cron" : [ {
"runnable" : {
"target" : "com.example.Processor.processOrders"
},
"expression" : "0 0 0/3 1/1 * ?"
} ],
"fixedDelay" : [ {
"runnable" : {
"target" : "com.example.Processor.purge"
},
"initialDelay" : 5000,
"interval" : 5000
} ],
"fixedRate" : [ {
"runnable" : {
"target" : "com.example.Processor.retrieveIssues"
},
"initialDelay" : 10000,
"interval" : 3000
} ]
}
/actuator/scheduledtasks
Inspired by a proposal from
Huang YunKun
Builds on top of improvements in
Spring Framework 5.0
"cron" : [ {
"runnable" : {
"target" : "com.example.Processor.processOrders"
},
"expression" : "0 0 0/3 1/1 * ?"
}
"fixedDelay" : [ {
"runnable" : {
"target" : "com.example.Processor.purge"
},
"initialDelay" : 5000,
"interval" : 5000
}

7. 7
{
"sessions" : [ {
"id" : "d66667e1-bcf1-453a-89f2-1d777439c4de",
"attributeNames" : [ ],
"creationTime" : "2018-05-09T11:28:40.594Z",
"lastAccessedTime" : "2018-05-09T13:28:28.594Z",
"maxInactiveInterval" : 1800,
"expired" : false
}, {
"id" : "85af4f77-319f-4912-8e81-f40c9de63735",
"attributeNames" : [ ],
"creationTime" : "2018-05-09T01:28:40.593Z",
"lastAccessedTime" : "2018-05-09T13:27:55.593Z",
"maxInactiveInterval" : 1800,
"expired" : false
}, {
"id" : "4db5efcc-99cb-4d05-a52c-b49acfbb7ea9",
"attributeNames" : [ ],
"creationTime" : "2018-05-09T08:28:40.594Z",
"lastAccessedTime" : "2018-05-09T13:28:03.594Z",
"maxInactiveInterval" : 1800,
"expired" : false
} ]
}
/actuator/sessions
Contributed by Vedran Pavic
{
"id" : "85af4f77-319f-4912-8e81-f40c9de63735",
"attributeNames" : [ ],
"creationTime" : "2018-05-09T01:28:40.593Z",
"lastAccessedTime" : "2018-05-09T13:27:55.593Z",
"maxInactiveInterval" : 1800,
"expired" : false
}

8. 8
{
"cacheManagers" : {
"anotherCacheManager" : {
"caches" : {
"countries" : {
"target" :
"java.util.concurrent.ConcurrentHashMap"
}
}
},
"cacheManager" : {
"caches" : {
"cities" : {
"target" : "java.util.concurrent.ConcurrentHashMap"
},
"countries" : {
“target" : "java.util.concurrent.ConcurrentHashMap"
}
}
}
}
}
/actuator/caches
Contributed by
Johannes Edmeier
"cacheManager" : {
"caches" : {
"cities" : {
"target" : "java.util.concurrent.ConcurrentHashMap"
},
"countries" : {
"target" : "java.util.concurrent.ConcurrentHashMap"
}
}
}
{
"target" : "java.util.concurrent.ConcurrentHashMap",
"name" : "cities",
"cacheManager" : "cacheManager"
}
/{name}

9. 9
{
"contentDescriptor" : {
"providerVersion" : “5.1.0.RC1”,
"providerFormatVersion" : 1.0,
"provider" : "spring-integration"
},
"nodes" : [ {
"nodeId" : 1,
"name" : "nullChannel",
"componentType" : "channel"
}, {
"nodeId" : 2,
"name" : "errorChannel",
"componentType" : "publish-subscribe-channel"
}, {
"nodeId" : 3,
"name" : "_errorLogger",
"componentType" : "logging-channel-adapter"
} ],
"links" : [ {
"from" : 2,
"to" : 3,
"type" : "input"
} ]
}
/actuator/integrationgraph
Contributed by Tim Ysewyn
"links" : [ {
"from" : 2,
"to" : 3,
"type" : "input"
} ]
"nodes" : [ {
"nodeId" : 1,
"name" : "nullChannel",
"componentType" : "channel"
} ]

10. 10
{
"status" : "UP",
"details" : {
"db" : {
"status" : "UP",
"details" : {
"database" : "HSQL Database Engine",
"hello" : 1
}
},
"broker" : {
"status" : "UP",
"details" : {
"us1" : {
"status" : "UP",
"details" : {
"version" : "1.0.2"
}
},
"us2" : {
"status" : "UP",
"details" : {
"version" : "1.0.4"
}}}}}}
/actuator/health /{component}
{
"status" : "UP",
"details" : {
"us1" : {
"status" : "UP",
"details" : {
"version" : "1.0.2"
}
},
"us2" : {
"status" : "UP",
"details" : {
"version" : "1.0.4"
}}}}
{
"status" : "UP",
"details" : {
"version" : "1.0.2"
}
}
/{instance}

11. CloudFoundry Integration

12. CloudFoundry Integration
• Endpoints available under /cloudfoundryapplication
• Requires a valid UAA token
• management.cloudfoundry.enabled
• Jersey, WebFlux, or Spring MVC
12

13. Web API documentation

14. Writing your own endpoints

15. 15
/**
* {@link Endpoint} to expose a user's {@link Session}s.
*
* @author Vedran Pavic
* @since 2.0.0
*/
@Endpoint(id = "sessions")
public class SessionsEndpoint {
// …
}
@Endpoint(id = "sessions")
http://example.com/actuator/
sessions

16. 16
@ReadOperation
public SessionsReport sessionsForUsername(String username) {
Map<String, ? extends Session> sessions =
this.sessionRepository.findByIndexNameAndIndexValue(
FindByIndexNameSessionRepository.PRINCIPAL_NAME_INDEX_NAME,
username);
return new SessionsReport(sessions);
}
@ReadOperation
(String username)SessionsReport
GET http://example.com/actuator/sessions
username
? =alice

17. 17
@ReadOperation
public SessionDescriptor getSession(@Selector String sessionId) {
Session session = this.sessionRepository.findById(sessionId);
if (session == null) {
return null;
}
return new SessionDescriptor(session);
}
@ReadOperation
(@Selector String sessionId)SessionDescriptor
GET http://example.com/actuator/sessions
sessionId
/{ }

18. 18
@DeleteOperation
public void deleteSession(@Selector String sessionId) {
this.sessionRepository.deleteById(sessionId);
}
@DeleteOperation
@Selector String sessionId
DELETE http://example.com/actuator/sessions
sessionId
/{ }
void

19. 19
@Endpoint(id = "loggers")
public class LoggersEndpoint {
@WriteOperation
public void configureLogLevel(@Selector String name,
@Nullable LogLevel configuredLevel) {
Assert.notNull(name, "Name must not be empty");
this.loggingSystem.setLogLevel(name, configuredLevel);
}
}
@Endpoint(id = "loggers")
@WriteOperation
void @Selector String name
@Nullable LogLevel configuredLevel
POST http://example.com/actuator/loggers
name
/{ }
{
" ": "DEBUG"
}
configuredLevel

20. Writing your own endpoints
Beyond the basics

21. 21
@EndpointWebExtension(endpoint = HealthEndpoint.class)
public class HealthEndpointWebExtension {
@ReadOperation
public WebEndpointResponse<Health> getHealth(
SecurityContext securityContext) {
return this.responseMapper.map(
this.delegate.health(), securityContext);
}
}
@EndpointWebExtension(endpoint = HealthEndpoint.class)
WebEndpointResponse<Health>
SecurityContext securityContext

22. 22
@ServletEndpoint
@ControllerEndpoint
@RestControllerEndpoint

23. Thanks!
Madhura Bhave
@madhurabhave23