[[production-ready]]
= Spring Boot Actuator: Production-ready features

[partintro]
--
Spring Boot includes a number of additional features to help you monitor and manage your
application when you push it to production. You can choose to manage and monitor your
application by using HTTP endpoints or with JMX. Auditing, health, and metrics gathering
can also be automatically applied to your application.
--



[[production-ready-enabling]]
== Enabling Production-ready Features
The {github-code}/spring-boot-project/spring-boot-actuator[`spring-boot-actuator`] module
provides all of Spring Boot's production-ready features. The simplest way to enable the
features is to add a dependency to the `spring-boot-starter-actuator` '`Starter`'.

.Definition of Actuator
****
An actuator is a manufacturing term that refers to a mechanical device for moving or
controlling something. Actuators can generate a large amount of motion from a small
change.
****

To add the actuator to a Maven based project, add the following '`Starter`' dependency:

[source,xml,indent=0]
----
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-actuator</artifactId>
		</dependency>
	</dependencies>
----

For Gradle, use the following declaration:

[source,groovy,indent=0]
----
	dependencies {
		compile("org.springframework.boot:spring-boot-starter-actuator")
	}
----



[[production-ready-endpoints]]
== Endpoints
Actuator endpoints let you monitor and interact with your application. Spring Boot
includes a number of built-in endpoints and lets you add your own. For example, the
`health` endpoint provides basic application health information.

Each individual endpoint can be <<production-ready-endpoints-enabling-endpoints, enabled
or disabled>>. This controls whether or not the endpoint is created and its bean exists in
the application context. To be remotely accessible an endpoint also has to be
<<production-ready-endpoints-exposing-endpoints, exposed via JMX or HTTP>>. Most
applications choose HTTP, where the ID of the endpoint along with a prefix of `/actuator`
is mapped to a URL. For example, by default, the `health` endpoint is mapped to
`/actuator/health`.

The following technology-agnostic endpoints are available:

[cols="2,5,2"]
|===
| ID | Description | Enabled by default

|`auditevents`
|Exposes audit events information for the current application.
|Yes

|`beans`
|Displays a complete list of all the Spring beans in your application.
|Yes

|`conditions`
|Shows the conditions that were evaluated on configuration and auto-configuration
classes and the reasons why they did or did not match.
|Yes

|`configprops`
|Displays a collated list of all `@ConfigurationProperties`.
|Yes

|`env`
|Exposes properties from Spring's `ConfigurableEnvironment`.
|Yes

|`flyway`
|Shows any Flyway database migrations that have been applied.
|Yes

|`health`
|Shows application health information.
|Yes

|`httptrace`
|Displays HTTP trace information (by default, the last 100 HTTP request-response
exchanges).
|Yes

|`info`
|Displays arbitrary application info.
|Yes

|`loggers`
|Shows and modifies the configuration of loggers in the application.
|Yes

|`liquibase`
|Shows any Liquibase database migrations that have been applied.
|Yes

|`metrics`
|Shows '`metrics`' information for the current application.
|Yes

|`mappings`
|Displays a collated list of all `@RequestMapping` paths.
|Yes

|`scheduledtasks`
|Displays the scheduled tasks in your application.
|Yes

|`sessions`
|Allows retrieval and deletion of user sessions from a Spring Session-backed session
store. Not available when using Spring Session's support for reactive web applications.
|Yes

|`shutdown`
|Lets the application be gracefully shutdown.
|No

|`threaddump`
|Performs a thread dump.
|Yes

|===

If your application is a web application (Spring MVC, Spring WebFlux, or Jersey), you can
use the following additional endpoints:

[cols="2,5,2"]
|===
| ID | Description | Enabled by default

|`heapdump`
|Returns a GZip compressed `hprof` heap dump file.
|Yes

|`jolokia`
|Exposes JMX beans over HTTP (when Jolokia is on the classpath, not available for WebFlux).
|Yes

|`logfile`
|Returns the contents of the logfile (if `logging.file` or `logging.path` properties have
been set). Supports the use of the HTTP `Range` header to retrieve part of the log file's
content.
|Yes

|`prometheus`
|Exposes metrics in a format that can be scraped by a Prometheus server.
|Yes

|===

To learn more about the Actuator's endpoints and their request and response formats,
please refer to the separate API documentation ({spring-boot-actuator-api}/html[HTML] or
{spring-boot-actuator-api}/pdf/spring-boot-actuator-web-api.pdf[PDF]).



[[production-ready-endpoints-enabling-endpoints]]
=== Enabling Endpoints
By default, all endpoints except for `shutdown` are enabled. To configure the enablement
of an endpoint, use its `management.endpoint.<id>.enabled` property. The following
example enables the `shutdown` endpoint:

[source,properties,indent=0]
----
	management.endpoint.shutdown.enabled=true
----

If you prefer endpoint enablement to be opt-in rather than opt-out, set the
`management.endpoints.enabled-by-default` property to `false` and use individual endpoint
`enabled` properties to opt back in. The following example enables the `info` endpoint and
disables all other endpoints:

[source,properties,indent=0]
----
	management.endpoints.enabled-by-default=false
	management.endpoint.info.enabled=true
----

NOTE: Disabled endpoints are removed entirely from the application context. If you want
to change only the technologies over which an endpoint is exposed, use the
<<production-ready-endpoints-exposing-endpoints, `expose` and `exclude` properties>>
instead.



[[production-ready-endpoints-exposing-endpoints]]
=== Exposing Endpoints
Since Endpoints may contain sensitive information, careful consideration should be given
about when to expose them. The following table shows the default exposure for the built-in
endpoints:

[cols="1,1,1"]
|===
| ID | JMX | Web

|`auditevents`
|Yes
|No

|`beans`
|Yes
|No

|`conditions`
|Yes
|No

|`configprops`
|Yes
|No

|`env`
|Yes
|No

|`flyway`
|Yes
|No

|`health`
|Yes
|Yes

|`heapdump`
|N/A
|No

|`httptrace`
|Yes
|No

|`info`
|Yes
|Yes

|`jolokia`
|N/A
|No

|`logfile`
|N/A
|No

|`loggers`
|Yes
|No

|`liquibase`
|Yes
|No

|`metrics`
|Yes
|No

|`mappings`
|Yes
|No

|`prometheus`
|N/A
|No

|`scheduledtasks`
|Yes
|No

|`sessions`
|Yes
|No

|`shutdown`
|Yes
|No

|`threaddump`
|Yes
|No

|===

To change which endpoints are exposed, use the following technology-specific `expose` and
`exclude` properties:

[cols="3,1"]
|===
|Property | Default

|`management.endpoints.jmx.exclude`
|

|`management.endpoints.jmx.expose`
| `*`

|`management.endpoints.web.exclude`
|

|`management.endpoints.web.expose`
| `info, health`

|===

The `expose` property lists the IDs of the endpoints that are exposed. The `exclude`
property lists the IDs of the endpoints that should not be exposed.  The `exclude`
property takes precedence over the `expose` property. Both `expose` and `exclude` properties
can be configured with a list of endpoint IDs.

For example, to stop exposing all endpoints over JMX and only expose the `health` and `info`
endpoints, use the following property:

[source,properties,indent=0]
----
	management.endpoints.jmx.expose=health,info
----

`*` can be used to select all endpoints. For example, to expose everything over HTTP
except the `env` and `beans` endpoints, use the following properties:

[source,properties,indent=0]
----
	management.endpoints.web.expose=*
	management.endpoints.web.exclude=env,beans
----

NOTE: If your application is exposed publicly, we strongly recommend that you also
<<production-ready-endpoints-security, secure your endpoints>>.

TIP: If you want to implement your own strategy for when endpoints are exposed, you can
register an `EndpointFilter` bean.



[[production-ready-endpoints-security]]
=== Securing HTTP Endpoints
You should take care to secure HTTP endpoints in the same way that you would any other
sensitive URL. If Spring Security is present, endpoints are secured by default using
Spring Security’s content-negotiation strategy. If you wish to configure custom security
for HTTP endpoints, for example, only allow users with a certain role to access them,
Spring Boot provides some convenient `RequestMatcher` objects that can be used in
combination with Spring Security.

A typical Spring Security configuration might look something like the following example:

[source,java,indent=0]
----
	@Configuration
	public class ActuatorSecurity extends WebSecurityConfigurerAdapter {

		@Override
		protected void configure(HttpSecurity http) throws Exception {
			http.requestMatcher(EndpointRequest.toAnyEndpoint()).authorizeRequests()
					.anyRequest().hasRole("ENDPOINT_ADMIN")
					.and()
				.httpBasic();
		}

	}
----

The preceding example uses `EndpointRequest.toAnyEndpoint()` to match a request to any
endpoint and then ensures that all have the `ENDPOINT_ADMIN` role. Several other matcher
methods are also available on `EndpointRequest`. See the API documentation
({spring-boot-actuator-api}/html[HTML] or
{spring-boot-actuator-api}/pdf/spring-boot-actuator-web-api.pdf[PDF]) for details.

If you deploy applications behind a firewall, you may prefer that all your actuator
endpoints can be accessed without requiring authentication. You can do so by changing the
`management.endpoints.web.expose` property, as follows:

.application.properties
[source,properties,indent=0]
----
	management.endpoints.web.expose=*
----

Additionally, if Spring Security is present, you would need to add custom security
configuration that allows unauthenticated access to the endpoints as shown in the
following example:

[source,java,indent=0]
----
	@Configuration
	public class ActuatorSecurity extends WebSecurityConfigurerAdapter {

		@Override
		protected void configure(HttpSecurity http) throws Exception {
			http.requestMatcher(EndpointRequest.toAnyEndpoint()).authorizeRequests()
				.anyRequest().permitAll()
		}

	}
----



[[production-ready-endpoints-caching]]
=== Configuring Endpoints
Endpoints automatically cache responses to read operations that do not take any
parameters. To configure the amount of time for which an endpoint will cache a response,
use its `cache.time-to-live` property. The following example sets the time-to-live of
the `beans` endpoint's cache to 10 seconds:

.application.properties
[source,properties,indent=0]
----
	management.endpoint.beans.cache.time-to-live=10s
----

NOTE: The prefix `management.endpoint.<name>` is used to uniquely identify the
endpoint that is being configured.



[[production-ready-endpoint-hypermedia]]
=== Hypermedia for Actuator Web Endpoints
A "`discovery page`" is added with links to all the endpoints. The "`discovery page`" is
available on `/actuator` by default.

When a custom management context path is configured, the "`discovery page`" automatically
moves from `/actuator` to the root of the management context. For example, if the
management context path is `/management`, then the discovery page is available from
`/management`. When the management context path is set to `/`, the discovery page is
disabled to prevent the possibility of a clash with other mappings.



[[production-ready-endpoint-custom-mapping]]
=== Actuator Web Endpoint Paths
By default, endpoints are exposed over HTTP under the `/actuator` path by using the ID of
the endpoint. For example, the `beans` endpoint is exposed under `/actuator/beans`. If you
want to map endpoints to a different path, you can use the
`management.endpoints.web.path-mapping` property. Also,  if you want change the base path,
you can use `management.endpoints.web.base-path`.

The following example remaps `/actuator/health` to `/healthcheck`:

.application.properties
[source,properties,indent=0]
----
	management.endpoints.web.base-path=/
	management.endpoints.web.path-mapping.health=healthcheck
----



[[production-ready-endpoint-cors]]
=== CORS Support
https://en.wikipedia.org/wiki/Cross-origin_resource_sharing[Cross-origin resource sharing]
(CORS) is a https://www.w3.org/TR/cors/[W3C specification] that lets you specify in a
flexible way what kind of cross-domain requests are authorized. If you use Spring MVC or
Spring WebFlux, Actuator's web endpoints can be configured to support such scenarios.

CORS support is disabled by default and is only enabled once the
`management.endpoints.web.cors.allowed-origins` property has been set. The following
configuration permits `GET` and `POST` calls from the `example.com` domain:

[source,properties,indent=0]
----
	management.endpoints.web.cors.allowed-origins=http://example.com
	management.endpoints.web.cors.allowed-methods=GET,POST
----

TIP: See
{sc-spring-boot-actuator-autoconfigure}/endpoint/web/CorsEndpointProperties.{sc-ext}[CorsEndpointProperties]
for a complete list of options.



[[production-ready-customizing-endpoints-programmatically]]
=== Adding Custom Endpoints
If you add a `@Bean` annotated with `@Endpoint`, any methods annotated with
`@ReadOperation`, `@WriteOperation`, or `@DeleteOperation` are automatically exposed over
JMX and, in a web application, over HTTP as well.

You can also write technology-specific endpoints by using `@JmxEndpoint` or
`@WebEndpoint`. These endpoints are filtered to their respective technologies. For
example, `@WebEndpoint` is exposed only over HTTP and not over JMX.

Finally, you can write technology-specific extensions by using `@EndpointWebExtension` and
`@EndpointJmxExtension`. These annotations let you provide technology-specific operations
to augment an existing endpoint.

TIP: If you add endpoints as a library feature, consider adding a configuration class
annotated with `@ManagementContextConfiguration` to `/META-INF/spring.factories` under the
following key:
`org.springframework.boot.actuate.autoconfigure.web.ManagementContextConfiguration`. If
you do so and if your users ask for a separate management port or address, the endpoint
moves to a child context with all the other web endpoints.



[[production-ready-health]]
=== Health Information
You can use health information to check the status of your running application. It is
often used by monitoring software to alert someone when a production system goes down.
The information exposed by the `health` endpoint depends on the
`management.endpoint.health.show-details` property which can be configured with one of the
following values:

[cols="1, 3"]
|===
|Name |Description

|`never`
|Details are never shown.

|`when-authenticated`
|Details are only shown to authenticated users.

|`always`
|Details are shown to all users.
|===

The default value is `when-authenticated`.

NOTE: If you have secured your application and wish to use `always`, your security
configuration must permit access to the health endpoint for both authenticated and
unauthenticated users.

Health information is collected from all
{sc-spring-boot-actuator}/health/HealthIndicator.{sc-ext}[`HealthIndicator`] beans
defined in your `ApplicationContext`. Spring Boot includes a number of auto-configured
`HealthIndicators`, and you can also write your own. By default, the final system state
is derived by the `HealthAggregator`, which sorts the statuses from each
`HealthIndicator` based on an ordered list of statuses. The first status in the sorted
list is used as the overall health status. If no `HealthIndicator` returns a status that
is known to the `HealthAggregator`, an `UNKNOWN` status is used.



==== Auto-configured HealthIndicators
The following `HealthIndicators` are auto-configured by Spring Boot when appropriate:

[cols="4,6"]
|===
|Name |Description

|{sc-spring-boot-actuator}/cassandra/CassandraHealthIndicator.{sc-ext}[`CassandraHealthIndicator`]
|Checks that a Cassandra database is up.

|{sc-spring-boot-actuator}/system/DiskSpaceHealthIndicator.{sc-ext}[`DiskSpaceHealthIndicator`]
|Checks for low disk space.

|{sc-spring-boot-actuator}/jdbc/DataSourceHealthIndicator.{sc-ext}[`DataSourceHealthIndicator`]
|Checks that a connection to `DataSource` can be obtained.

|{sc-spring-boot-actuator}/elasticsearch/ElasticsearchHealthIndicator.{sc-ext}[`ElasticsearchHealthIndicator`]
|Checks that an Elasticsearch cluster is up.

|{sc-spring-boot-actuator}/influx/InfluxDbHealthIndicator.{sc-ext}[`InfluxDbHealthIndicator`]
|Checks that an InfluxDB server is up.

|{sc-spring-boot-actuator}/jms/JmsHealthIndicator.{sc-ext}[`JmsHealthIndicator`]
|Checks that a JMS broker is up.

|{sc-spring-boot-actuator}/kafka/KafkaHealthIndicator.{sc-ext}[`KafkaHealthIndicator`]
|Checks that a Kafka server is up.

|{sc-spring-boot-actuator}/mail/MailHealthIndicator.{sc-ext}[`MailHealthIndicator`]
|Checks that a mail server is up.

|{sc-spring-boot-actuator}/mongo/MongoHealthIndicator.{sc-ext}[`MongoHealthIndicator`]
|Checks that a Mongo database is up.

|{sc-spring-boot-actuator}/neo4j/Neo4jHealthIndicator.{sc-ext}[`Neo4jHealthIndicator`]
|Checks that a Neo4j server is up.

|{sc-spring-boot-actuator}/amqp/RabbitHealthIndicator.{sc-ext}[`RabbitHealthIndicator`]
|Checks that a Rabbit server is up.

|{sc-spring-boot-actuator}/redis/RedisHealthIndicator.{sc-ext}[`RedisHealthIndicator`]
|Checks that a Redis server is up.

|{sc-spring-boot-actuator}/solr/SolrHealthIndicator.{sc-ext}[`SolrHealthIndicator`]
|Checks that a Solr server is up.

|===

TIP: You can disable them all by setting the `management.health.defaults.enabled`
property.


==== Writing Custom HealthIndicators
To provide custom health information, you can register Spring beans that implement the
{sc-spring-boot-actuator}/health/HealthIndicator.{sc-ext}[`HealthIndicator`] interface.
You need to provide an implementation of the `health()` method and return a `Health`
response. The `Health` response should include a status and can optionally include
additional details to be displayed. The following code shows a sample `HealthIndicator`
implementation:

[source,java,indent=0]
----
	import org.springframework.boot.actuate.health.Health;
	import org.springframework.boot.actuate.health.HealthIndicator;
	import org.springframework.stereotype.Component;

	@Component
	public class MyHealthIndicator implements HealthIndicator {

		@Override
		public Health health() {
			int errorCode = check(); // perform some specific health check
			if (errorCode != 0) {
				return Health.down().withDetail("Error Code", errorCode).build();
			}
			return Health.up().build();
		}

	}
----

NOTE: The identifier for a given `HealthIndicator` is the name of the bean without the
`HealthIndicator` suffix, if it exists. In the preceding example, the health information
is available in an entry named `my`.

In addition to Spring Boot's predefined
{sc-spring-boot-actuator}/health/Status.{sc-ext}[`Status`] types, it is also possible for
`Health` to return a custom `Status` that represents a new system state. In such cases, a
custom implementation of the
{sc-spring-boot-actuator}/health/HealthAggregator.{sc-ext}[`HealthAggregator`] interface
also needs to be provided, or the default implementation has to be configured by using
the `management.health.status.order` configuration property.

For example, assume a new `Status` with code `FATAL` is being used in one of your
`HealthIndicator` implementations. To configure the severity order, add the following
property to your application properties:

[source,properties,indent=0]
----
	management.health.status.order=FATAL, DOWN, OUT_OF_SERVICE, UNKNOWN, UP
----

The HTTP status code in the response reflects the overall health status (for example,
`UP` maps to 200, while `OUT_OF_SERVICE` and `DOWN` map to 503). You might also want to
register custom status mappings if you access the health endpoint over HTTP. For example,
the following property maps `FATAL` to 503 (service unavailable):

[source,properties,indent=0]
----
	management.health.status.http-mapping.FATAL=503
----

TIP: If you need more control, you can define your own `HealthStatusHttpMapper` bean.

The following table shows the default status mappings for the built-in statuses:

[cols="1,3"]
|===
|Status |Mapping

|DOWN
|SERVICE_UNAVAILABLE (503)

|OUT_OF_SERVICE
|SERVICE_UNAVAILABLE (503)

|UP
|No mapping by default, so http status is 200

|UNKNOWN
|No mapping by default, so http status is 200
|===



[[reactive-health-indicators]]
==== Reactive Health Indicators
For reactive applications, such as those using Spring WebFlux, `ReactiveHealthIndicator`
provides a non-blocking contract for getting application health. Similar to a traditional
`HealthIndicator`, health information is collected from all
{sc-spring-boot-actuator}/health/ReactiveHealthIndicator.{sc-ext}[`ReactiveHealthIndicator`]
beans defined in your `ApplicationContext`. Regular `HealthIndicator` beans that do not
check against a reactive API are included and executed on the elastic scheduler.

To provide custom health information from a reactive API, you can register Spring beans
that implement the
{sc-spring-boot-actuator}/health/ReactiveHealthIndicator.{sc-ext}[`ReactiveHealthIndicator`]
interface. The following code shows a sample `ReactiveHealthIndicator` implementation:

[source,java,indent=0]
----
	@Component
	public class MyReactiveHealthIndicator implements ReactiveHealthIndicator {

		@Override
		public Mono<Health> health() {
			return doHealthCheck() //perform some specific health check that returns a Mono<Health>
				.onErrorResume(ex -> Mono.just(new Health.Builder().down(ex).build())));
		}

	}
----

TIP: To handle the error automatically, consider extending from
`AbstractReactiveHealthIndicator`.



==== Auto-configured ReactiveHealthIndicators
The following `ReactiveHealthIndicators` are auto-configured by Spring Boot when
appropriate:

[cols="1,4"]
|===
|Name |Description

|{sc-spring-boot-actuator}/redis/RedisReactiveHealthIndicator.{sc-ext}[`RedisReactiveHealthIndicator`]
|Checks that a Redis server is up.
|===

TIP: If necessary, reactive indicators replace the regular ones. Also, any
`HealthIndicator` that is not handled explicitly is wrapped automatically.



[[production-ready-application-info]]
=== Application Information
Application information exposes various information collected from all
{sc-spring-boot-actuator}/info/InfoContributor.{sc-ext}[`InfoContributor`] beans defined
in your `ApplicationContext`. Spring Boot includes a number of auto-configured
`InfoContributor` beans, and you can write your own.

[[production-ready-application-info-autoconfigure]]
==== Auto-configured InfoContributors

The following `InfoContributor` beans are auto-configured by Spring Boot, when
appropriate:

[cols="1,4"]
|===
|Name |Description

|{sc-spring-boot-actuator}/info/EnvironmentInfoContributor.{sc-ext}[`EnvironmentInfoContributor`]
|Exposes any key from the `Environment` under the `info` key.

|{sc-spring-boot-actuator}/info/GitInfoContributor.{sc-ext}[`GitInfoContributor`]
|Exposes git information if a `git.properties` file is available.

|{sc-spring-boot-actuator}/info/BuildInfoContributor.{sc-ext}[`BuildInfoContributor`]
|Exposes build information if a `META-INF/build-info.properties` file is available.
|===

TIP: It is possible to disable them all by setting the `management.info.defaults.enabled`
property.

[[production-ready-application-info-env]]
==== Custom Application Information
You can customize the data exposed by the `info` endpoint by setting `+info.*+` Spring
properties. All `Environment` properties under the `info` key are automatically exposed.
For example, you could add the following settings to your `application.properties` file:

[source,properties,indent=0]
----
	info.app.encoding=UTF-8
	info.app.java.source=1.8
	info.app.java.target=1.8
----

[TIP]
====
Rather than hardcoding those values, you could also
<<howto.adoc#howto-automatic-expansion,expand info properties at build time>>.

Assuming you use Maven, you could rewrite the preceding example as follows:

[source,properties,indent=0]
----
	info.app.encoding=@project.build.sourceEncoding@
	info.app.java.source=@java.version@
	info.app.java.target=@java.version@
----
====



[[production-ready-application-info-git]]
==== Git Commit Information
Another useful feature of the `info` endpoint is its ability to publish information about
the state of your `git` source code repository when the project was built. If a
`GitProperties` bean is available, the `git.branch`, `git.commit.id`, and
`git.commit.time` properties are exposed.

TIP: A `GitProperties` bean is auto-configured if a `git.properties` file is available at
the root of the classpath. See
"<<howto.adoc#howto-git-info,Generate git information>>" for more details.

If you want to display the full git information (that is, the full content of
`git.properties`), use the `management.info.git.mode` property, as follows:

[source,properties,indent=0]
----
	management.info.git.mode=full
----



[[production-ready-application-info-build]]
==== Build Information
If a `BuildProperties` bean is available, the `info` endpoint can also publish
information about your build. This happens if a `META-INF/build-info.properties` file is
available in the classpath.

TIP: The Maven and Gradle plugins can both generate that file. See
"<<howto.adoc#howto-build-info,Generate build information>>" for more details.


[[production-ready-application-info-custom]]
==== Writing Custom InfoContributors
To provide custom application information, you can register Spring beans that implement
the {sc-spring-boot-actuator}/info/InfoContributor.{sc-ext}[`InfoContributor`] interface.

The following example contributes an `example` entry with a single value:

[source,java,indent=0]
----
	import java.util.Collections;

	import org.springframework.boot.actuate.info.Info;
	import org.springframework.boot.actuate.info.InfoContributor;
	import org.springframework.stereotype.Component;

	@Component
	public class ExampleInfoContributor implements InfoContributor {

		@Override
		public void contribute(Info.Builder builder) {
			builder.withDetail("example",
					Collections.singletonMap("key", "value"));
		}

	}
----

If you reach the `info` endpoint, you should see a response that contains the following
additional entry:

[source,json,indent=0]
----
	{
		"example": {
			"key" : "value"
		}
	}
----



[[production-ready-monitoring]]
== Monitoring and Management over HTTP
If you are developing a web application, Spring Boot Actuator auto-configures all
enabled endpoints to be exposed over HTTP. The default convention is to use the `id` of
the endpoint with a prefix of `/actuator` as the URL path. For example, `health` is
exposed as `/actuator/health`.

TIP: Actuator is supported natively with Spring MVC, Spring WebFlux, and Jersey.



[[production-ready-customizing-management-server-context-path]]
=== Customizing the Management Endpoint Paths
Sometimes, it is useful to customize the prefix for the management endpoints. For
example, your application might already use `/actuator` for another purpose. You can
use the `management.endpoints.web.base-path` property to change the prefix for your
management endpoint, as shown in the following example:

[source,properties,indent=0]
----
	management.endpoints.web.base-path=/manage
----

The preceding `application.properties` example changes the endpoint from
`/actuator/{id}` to `/manage/{id}` (for example, `/manage/info`).

NOTE: Unless the management port has been configured to
<<production-ready-customizing-management-server-port,expose endpoints by using a
different HTTP port>>, `management.endpoints.web.base-path` is relative to
`server.servlet.context-path`. If `management.server.port` is configured,
`management.endpoints.web.base-path` is relative to
`management.server.servlet.context-path`.



[[production-ready-customizing-management-server-port]]
=== Customizing the Management Server Port
Exposing management endpoints by using the default HTTP port is a sensible choice for
cloud-based deployments. If, however, your application runs inside your own data center,
you may prefer to expose endpoints by using a different HTTP port.

You can set the `management.server.port` property to change the HTTP port, as shown in
the following example:

[source,properties,indent=0]
----
	management.server.port=8081
----



[[production-ready-management-specific-ssl]]
=== Configuring Management-specific SSL
When configured to use a custom port, the management server can also be configured with
its own SSL by using the various `management.server.ssl.*` properties. For example, doing
so lets a management server be available over HTTP while the main application uses HTTPS,
as shown in the following property settings:

[source,properties,indent=0]
----
	server.port=8443
	server.ssl.enabled=true
	server.ssl.key-store=classpath:store.jks
	server.ssl.key-password=secret
	management.server.port=8080
	management.server.ssl.enabled=false
----

Alternatively, both the main server and the management server can use SSL but with
different key stores, as follows:

[source,properties,indent=0]
----
	server.port=8443
	server.ssl.enabled=true
	server.ssl.key-store=classpath:main.jks
	server.ssl.key-password=secret
	management.server.port=8080
	management.server.ssl.enabled=true
	management.server.ssl.key-store=classpath:management.jks
	management.server.ssl.key-password=secret
----



[[production-ready-customizing-management-server-address]]
=== Customizing the Management Server Address
You can customize the address that the management endpoints are available on by setting
the `management.server.address` property. Doing so can be useful if you want to listen
only on an internal or ops-facing network or to listen only for connections from
`localhost`.

NOTE: You can listen on a different address only when the port differs from the main
server port.

The following example `application.properties` does not allow remote management
connections:

[source,properties,indent=0]
----
	management.server.port=8081
	management.server.address=127.0.0.1
----



[[production-ready-disabling-http-endpoints]]
=== Disabling HTTP Endpoints
If you do not want to expose endpoints over HTTP, you can set the management port to
`-1`, as shown in the following example:

[source,properties,indent=0]
----
	management.server.port=-1
----



[[production-ready-jmx]]
== Monitoring and Management over JMX
Java Management Extensions (JMX) provide a standard mechanism to monitor and manage
applications. By default, Spring Boot exposes management endpoints as JMX MBeans under
the `org.springframework.boot` domain.



[[production-ready-custom-mbean-names]]
=== Customizing MBean Names
The name of the MBean is usually generated from the `id` of the endpoint. For example, the
`health` endpoint is exposed as `org.springframework.boot:type=Endpoint,name=Health`.

If your application contains more than one Spring `ApplicationContext`, you may find that
names clash. To solve this problem, you can set the
`management.endpoints.jmx.unique-names` property to `true` so that MBean names are always
unique.

You can also customize the JMX domain under which endpoints are exposed. The following
settings show an example of doing so in `application.properties`:

[source,properties,indent=0]
----
	management.endpoints.jmx.domain=com.example.myapp
	management.endpoints.jmx.unique-names=true
----



[[production-ready-disable-jmx-endpoints]]
=== Disabling JMX Endpoints
If you do not want to expose endpoints over JMX, you can set the
`management.endpoints.jmx.exclude` property to `*`, as shown in the following example:

[source,properties,indent=0]
----
	management.endpoints.jmx.exclude=*
----



[[production-ready-jolokia]]
=== Using Jolokia for JMX over HTTP
Jolokia is a JMX-HTTP bridge that provides an alternative method of accessing JMX beans.
To use Jolokia, include a dependency to `org.jolokia:jolokia-core`. For example, with
Maven, you would add the following dependency:

[source,xml,indent=0]
----
	<dependency>
		<groupId>org.jolokia</groupId>
		<artifactId>jolokia-core</artifactId>
 	</dependency>
----

The Jolokia endpoint can then be exposed by adding `jolokia` or `*` to the
`management.endpoints.web.expose` property. You can then access it by using
`/actuator/jolokia` on your management HTTP server.



[[production-ready-customizing-jolokia]]
==== Customizing Jolokia
Jolokia has a number of settings that you would traditionally configure by setting servlet
parameters. With Spring Boot, you can use your `application.properties` file. To do so,
prefix the parameter with `management.endpoint.jolokia.config.`, as shown in the following
example:

[source,properties,indent=0]
----
	management.endpoint.jolokia.config.debug=true
----



[[production-ready-disabling-jolokia]]
==== Disabling Jolokia
If you use Jolokia but do not want Spring Boot to configure it, set the
`management.endpoint.jolokia.enabled` property to `false`, as follows:

[source,properties,indent=0]
----
	management.jolokia.enabled=false
----



[[production-ready-loggers]]
== Loggers
Spring Boot Actuator includes the ability to view and configure the log levels of your
application at runtime. You can view either the entire list or an individual logger's
configuration, which is made up of both the explicitly configured logging level as well
as the effective logging level given to it by the logging framework.  These levels can be
one of:

* `TRACE`
* `DEBUG`
* `INFO`
* `WARN`
* `ERROR`
* `FATAL`
* `OFF`
* `null`

`null` indicates that there is no explicit configuration.



[[production-ready-logger-configuration]]
=== Configure a Logger
To configure a given logger, `POST` a partial entity to the resource's URI, as shown in
the following example:

[source,json,indent=0]
----
	{
		"configuredLevel": "DEBUG"
	}
----

TIP: To "`reset`" the specific level of the logger (and use the default configuration
instead), you can pass a value of `null` as the `configuredLevel`.



[[production-ready-metrics]]
== Metrics
Spring Boot Actuator provides dependency management and auto-configuration for
https://micrometer.io[Micrometer], an application metrics facade that supports numerous
monitoring systems, including:

- https://github.com/Netflix/atlas[Atlas]
- https://www.datadoghq.com[Datadog]
- http://ganglia.sourceforge.net[Ganglia]
- https://graphiteapp.org[Graphite]
- https://www.influxdata.com[Influx]
- https://prometheus.io[Prometheus]

NOTE: At the time of this writing, the number of monitoring systems supported by
Micrometer is growing rapidly. See the https://micrometer.io[Micrometer project] for more
information.

Micrometer provides a separate module for each supported monitoring system. Depending on
one (or more) of these modules is sufficient to get started with Micrometer in your
Spring Boot application. To learn more about Micrometer's capabilities, please refer to
its https://micrometer.io/docs[reference documentation].



[[production-ready-metrics-spring-mvc]]
=== Spring MVC Metrics
Auto-configuration enables the instrumentation of requests handled by Spring MVC. When
`management.metrics.web.server.auto-time-requests` is `true`, this instrumentation occurs
for all requests. Alternatively, when set to `false`, you can enable instrumentation by
adding `@Timed` to a request-handling method.

By default, metrics are generated with the name, `http.server.requests`. The name can be
customized by setting the `management.metrics.web.server.requests-metric-name` property.



[[production-ready-metrics-spring-mvc-tags]]
==== Spring MVC Metric Tags
By default, Spring MVC-related metrics are tagged with the following information:

* The request's method.
* The request's URI (templated if possible).
* The simple class name of any exception that was thrown while handling the request.
* The response's status.

To customize the tags, provide a `@Bean` that implements `WebMvcTagsProvider`.


[[production-ready-metrics-web-flux]]
=== WebFlux Metrics
Auto-configuration enables the instrumentation of all requests handled by WebFlux
controllers. You can also use a helper class, `RouterFunctionMetrics`, to instrument
applications that use WebFlux's functional programming model.

By default, metrics are generated with the name `http.server.requests`. You can customize
the name by setting the `management.metrics.web.server.requests-metric-name` property.



[[production-ready-metrics-web-flux-tags]]
==== WebFlux Metrics Tags
By default, WebFlux-related metrics for the annotation-based programming model are tagged
with the following information:

* The request's method.
* The request's URI (templated if possible).
* The simple class name of any exception that was thrown while handling the request.
* The response's status.

To customize the tags, provide a `@Bean` that implements `WebFluxTagsProvider`.

By default, metrics for the functional programming model are tagged with the following
information:

* The request's method
* The request's URI (templated if possible).
* The response's status.

To customize the tags, use the `defaultTags` method on your `RouterFunctionMetrics`
instance.



[[production-ready-metrics-rest-template]]
=== RestTemplate Metrics
The instrumentation of any `RestTemplate` created using the auto-configured
`RestTemplateBuilder` is enabled. It is also possible to apply
`MetricsRestTemplateCustomizer` manually.

By default, metrics are generated with the name, `http.client.requests`. The name can be
customized by setting the `management.metrics.web.client.requests-metric-name` property.



[[production-ready-metrics-rest-template-tags]]
==== RestTemplate Metric Tags
By default, metrics generated by an instrumented `RestTemplate` are tagged with the
following information:

* The request's method.
* The request's URI (templated if possible).
* The response's status.
* The request URI's host.



[[production-ready-metrics-cache]]
=== Cache metrics
Auto-configuration will enable the instrumentation of all available ``Cache``s on startup
with metrics prefixed with `cache.`. Cache instrumentation is standardized for a basic set
of metrics. Additional, cache-specific metrics are also available. Please refer to
https://micrometer.io/docs[the Micrometer documentation] for more details.

The following cache libraries are supported:

* Caffeine
* EhCache 2
* Hazelcast
* Any compliant JCache (JSR-107) implementation

Metrics are tagged by the name of the cache and by the name of the `CacheManager` that is
derived from the bean name.

NOTE: Only caches that are available on startup are bound to the registry. For caches
created on-the-fly or programmatically after the startup phase, an explicit registration
is required. A `CacheMetricsRegistrar` bean is made available to make that process easier.



[[production-ready-metrics-jdbc]]
=== DataSource Metrics
Auto-configuration enables the instrumentation of all available ``DataSource`` objects
with a metric named `data.source`. Data source instrumentation results in gauges
representing the currently active, maximum allowed, and minimum allowed connections in the
pool. Each of these gauges has a name that is prefixed by `data.source` by default. The
prefix can be customized by setting the `management.metrics.jdbc.metric-name`
property.

Metrics are also tagged by the name of the `DataSource` computed based on the bean name.



[[production-ready-metrics-rabbitmq]]
=== RabbitMQ metrics
Auto-configuration will enable the instrumentation of all available RabbitMQ connection
factories with a metric named `rabbitmq`. The prefix can be customized by using the
`management.metrics.rabbitmq.metric-name` property.



[[production-ready-metrics-integration]]
=== Spring Integration Metrics
Auto-configuration enables binding of a number of Spring Integration-related metrics:

.General metrics
|===
| Metric | Description

| `spring.integration.channelNames`
| Number of Spring Integration channels

| `spring.integration.handlerNames`
| Number of Spring Integration handlers

| `spring.integration.sourceNames`
| Number of Spring Integration sources
|===

.Channel metrics
|===
| Metric | Description

| `spring.integration.channel.receives`
| Number of receives

| `spring.integration.channel.sendErrors`
| Number of failed sends

| `spring.integration.channel.sends`
| Number of successful sends
|===

.Handler metrics
|===
| Metric | Description

| `spring.integration.handler.duration.max`
| Maximum handler duration in milliseconds

| `spring.integration.handler.duration.min`
| Minimum handler duration in milliseconds

| `spring.integration.handler.duration.mean`
| Mean handler duration in milliseconds

| `spring.integration.handler.activeCount`
| Number of active handlers
|===

.Source metrics
|===
| Metric | Description

| `spring.integration.source.messages`
| Number of successful source calls
|===



[[production-ready-metrics-per-meter-properties]]
=== Customizing individual meters
If you need to apply customizations to specific `Meter` instances you can use the
`io.micrometer.core.instrument.config.MeterFilter` interface. By default, all
`MeterFilter` beans will be automatically applied to the micrometer
`MeterRegistry.Config`.

For example, if you want to rename the `mytag.region` tag to `mytag.area` for
all meter IDs beginning with `com.example`, you can do the following:

[source,java,indent=0]
----
include::{code-examples}/actuate/metrics/MetricsFilterBeanExample.java[tag=configuration]
----

==== Per-meter properties
In addition to `MeterFilter` beans, it's also possible to apply a limited set of
customization on a per-meter basis using properties. Per-meter customizations apply to
any all meter IDs that start with the given name. For example, the following will disable
any meters that have an ID starting with `example.remote`

[source,properties,indent=0]
----
	management.metrics.enable.example.remote=false
----

The following properties allow per-meter customization:

.Per-meter customizations
|===
| Property | Description

| `management.metrics.enable`
| Whether to deny meters from emitting any metrics.

| `management.metrics.distribution.percentiles-histogram`
| Whether to publish a histogram suitable for computing aggregable (across dimension)
percentile approximations.

| `management.metrics.distribution.percentiles`
| Publish percentile values computed in your application

| `management.metrics.distribution.sla`
| Publish a cumulative histogram with buckets defined by your SLAs.

|===

For more details on concepts behind `percentiles-histogram`, `percentiles` and `sla`
refer to the {micrometer-concepts-documentation}#_histograms_and_percentiles["Histograms
and percentiles" section] of the micrometer documentation.



[[production-ready-auditing]]
== Auditing
Once Spring Security is in play, Spring Boot Actuator has a flexible audit framework that
publishes events (by default, "`authentication success`", "`failure`" and
"`access denied`" exceptions). This feature can be very useful for reporting and for
implementing a lock-out policy based on authentication failures. To customize published
security events, you can provide your own implementations of
`AbstractAuthenticationAuditListener` and `AbstractAuthorizationAuditListener`.

You can also use the audit services for your own business events. To do so, either inject
the existing `AuditEventRepository` into your own components and use that directly or
publish an `AuditApplicationEvent` with the Spring `ApplicationEventPublisher` (by
implementing `ApplicationEventPublisherAware`).



[[production-ready-http-tracing]]
== HTTP Tracing
Tracing is automatically enabled for all HTTP requests. You can view the `httptrace`
endpoint and obtain basic information about the last 100 request-response exchanges.



[[production-ready-http-tracing-custom]]
=== Custom HTTP tracing
To customize the items that are included in each trace, use the
`management.trace.http.include` configuration property.

By default, an `InMemoryHttpTraceRepository` that stores traces for the last 100
request-response exchanges is used. If you need to expand the capacity, you can define
your own instance of the `InMemoryHttpTraceRepository` bean. You can also create your own
alternative `HttpTraceRepository` implementation.



[[production-ready-process-monitoring]]
== Process Monitoring
In the `spring-boot` module, you can find two classes to create files that are often
useful for process monitoring:

* `ApplicationPidFileWriter` creates a file containing the application PID (by default,
in the application directory with a file name of `application.pid`).
* `WebServerPortFileWriter` creates a file (or files) containing the ports of the
running web server (by default, in the application directory with a file name of
`application.port`).

By default, these writers are not activated, but you can enable:

* <<production-ready-process-monitoring-configuration,By Extending Configuration>>
* <<production-ready-process-monitoring-programmatically>>



[[production-ready-process-monitoring-configuration]]
=== Extending Configuration
In the `META-INF/spring.factories` file, you can activate the listener(s) that writes a
PID file, as shown in the following example:

[indent=0]
----
	org.springframework.context.ApplicationListener=\
	org.springframework.boot.system.ApplicationPidFileWriter,\
	org.springframework.boot.system.EmbeddedServerPortFileWriter
----



[[production-ready-process-monitoring-programmatically]]
=== Programmatically
You can also activate a listener by invoking the `SpringApplication.addListeners(...)`
method and passing the appropriate `Writer` object. This method also lets you customize
the file name and path in the `Writer` constructor.



[[production-ready-cloudfoundry]]
== Cloud Foundry Support
Spring Boot's actuator module includes additional support that is activated when you
deploy to a compatible Cloud Foundry instance. The `/cloudfoundryapplication` path
provides an alternative secured route to all `@Endpoint` beans.

The extended support lets Cloud Foundry management UIs (such as the web application that
you can use to view deployed applications) be augmented with Spring Boot actuator
information. For example, an application status page may include full health information
instead of the typical "`running`" or "`stopped`" status.

NOTE: The `/cloudfoundryapplication` path is not directly accessible to regular users.
In order to use the endpoint, a valid UAA token must be passed with the request.



[[production-ready-cloudfoundry-disable]]
=== Disabling Extended Cloud Foundry Actuator Support
If you want to fully disable the `/cloudfoundryapplication` endpoints, you can add the
following setting to your `application.properties` file:


.application.properties
[source,properties,indent=0]
----
	management.cloudfoundry.enabled=false
----



[[production-ready-cloudfoundry-ssl]]
=== Cloud Foundry Self-signed Certificates
By default, the security verification for `/cloudfoundryapplication` endpoints makes SSL
calls to various Cloud Foundry services. If your Cloud Foundry UAA or Cloud Controller
services use self-signed certificates, you need to set the following property:

.application.properties
[source,properties,indent=0]
----
	management.cloudfoundry.skip-ssl-validation=true
----



=== Custom context path

If the server's context-path has been configured to anything other then `/`, the Cloud Foundry endpoints
will not be available at the root of the application. For example, if `server.servlet.context-path=/foo`,
Cloud Foundry endpoints will be available at `/foo/cloudfoundryapplication/*`.

If you expect the Cloud Foundry endpoints to always be available at `/cloudfoundryapplication/*`, regardless of
the server's context-path, you will need to explicitly configure that in your application. The configuration will differ
depending on the web server in use. For Tomcat, the following configuration can be added:

[source,java,indent=0]
----
	@Bean
	public TomcatEmbeddedServletContainerFactory servletContainerFactory() {
		return new TomcatEmbeddedServletContainerFactory() {
			@Override
			protected void prepareContext(Host host,
						ServletContextInitializer[] initializers) {
				super.prepareContext(host, initializers);
				StandardContext child = new StandardContext();
				child.addLifecycleListener(new Tomcat.FixContextListener());
				child.setPath("/cloudfoundryapplication");
				ServletContainerInitializer initializer = getServletContextInitializer(getContextPath());
				child.addServletContainerInitializer(initializer, Collections.emptySet());
				child.setCrossContext(true);
				host.addChild(child);
			}
		};
	}

	private ServletContainerInitializer getServletContextInitializer(String contextPath) {
		return (c, context) -> {
			Servlet servlet = new GenericServlet() {
				@Override
				public void service(ServletRequest req, ServletResponse res)
						throws ServletException, IOException {
					ServletContext context = req.getServletContext().getContext(contextPath);
					context.getRequestDispatcher("/cloudfoundryapplication").forward(req, res);
				}
			};
			context.addServlet("cloudfoundry", servlet).addMapping("/*");
		};
	}
----



[[production-ready-whats-next]]
== What to Read Next
If you want to explore some of the concepts discussed in this chapter, you can take a
look at the actuator {github-code}/spring-boot-samples[sample applications]. You also
might want to read about graphing tools such as http://graphite.wikidot.com/[Graphite].

Otherwise, you can continue on, to read about <<deployment.adoc#deployment, '`deployment
options`'>> or jump ahead for some in-depth information about Spring Boot's
_<<build-tool-plugins.adoc#build-tool-plugins, build tool plugins>>_.
