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.
You can enable or disable each individual endpoint and expose them (make them remotely accessible) over HTTP or JMX.
An endpoint is considered to be available when it is both enabled and exposed.
The built-in endpoints are auto-configured only when they are available.
Most applications choose exposure over HTTP, where the ID of the endpoint and a prefix of /actuator is mapped to a URL.
For example, by default, the health endpoint is mapped to /actuator/health.
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Tip
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To learn more about the Actuator’s endpoints and their request and response formats, see the separate API documentation ({spring-boot-actuator-restapi-docs}[HTML] or {spring-boot-actuator-restapi-pdfdocs}[PDF]). |
The following technology-agnostic endpoints are available:
| ID | Description |
|---|---|
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Exposes audit events information for the current application.
Requires an |
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Displays a complete list of all the Spring beans in your application. |
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Exposes available caches. |
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Shows the conditions that were evaluated on configuration and auto-configuration classes and the reasons why they did or did not match. |
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Displays a collated list of all |
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Exposes properties from Spring’s |
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Shows any Flyway database migrations that have been applied.
Requires one or more |
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Shows application health information. |
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Displays HTTP exchange information (by default, the last 100 HTTP request-response exchanges).
Requires an |
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Displays arbitrary application info. |
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Shows the Spring Integration graph.
Requires a dependency on |
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Shows and modifies the configuration of loggers in the application. |
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Shows any Liquibase database migrations that have been applied.
Requires one or more |
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Shows “metrics” information for the current application. |
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Displays a collated list of all |
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Shows information about Quartz Scheduler jobs. |
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Displays the scheduled tasks in your application. |
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Allows retrieval and deletion of user sessions from a Spring Session-backed session store. Requires a servlet-based web application that uses Spring Session. |
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Lets the application be gracefully shutdown. Only works when using jar packaging. Disabled by default. |
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Shows the startup steps data collected by the |
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Performs a thread dump. |
If your application is a web application (Spring MVC, Spring WebFlux, or Jersey), you can use the following additional endpoints:
| ID | Description |
|---|---|
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Returns a heap dump file.
On a HotSpot JVM, an |
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Returns the contents of the logfile (if the |
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Exposes metrics in a format that can be scraped by a Prometheus server.
Requires a dependency on |
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:
management:
endpoint:
shutdown:
enabled: trueIf you prefer endpoint enablement to be opt-in rather than opt-out, set the configprop: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:
management:
endpoints:
enabled-by-default: false
endpoint:
info:
enabled: true|
Note
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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 include and exclude properties instead.
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By default, only the health endpoint is exposed over HTTP and JMX. Since Endpoints may contain sensitive information, you should carefully consider when to expose them.
To change which endpoints are exposed, use the following technology-specific include and exclude properties:
| Property | Default |
|---|---|
configprop:management.endpoints.jmx.exposure.exclude[] |
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configprop:management.endpoints.jmx.exposure.include[] |
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configprop:management.endpoints.web.exposure.exclude[] |
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configprop:management.endpoints.web.exposure.include[] |
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The include 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 include property.
You can configure both the include and the exclude properties with a list of endpoint IDs.
For example, to only expose the health and info endpoints over JMX, use the following property:
management:
endpoints:
jmx:
exposure:
include: "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:
management:
endpoints:
web:
exposure:
include: "*"
exclude: "env,beans"|
Note
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* has a special meaning in YAML, so be sure to add quotation marks if you want to include (or exclude) all endpoints.
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Note
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If your application is exposed publicly, we strongly recommend that you also secure your endpoints. |
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Tip
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If you want to implement your own strategy for when endpoints are exposed, you can register an EndpointFilter bean.
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For security purposes, only the /health endpoint is exposed over HTTP by default.
You can use the configprop:management.endpoints.web.exposure.include[] property to configure the endpoints that are exposed.
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Note
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Before setting the management.endpoints.web.exposure.include, ensure that the exposed actuators do not contain sensitive information, are secured by placing them behind a firewall, or are secured by something like Spring Security.
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If Spring Security is on the classpath and no other SecurityFilterChain bean is present, all actuators other than /health are secured by Spring Boot auto-configuration.
If you define a custom SecurityFilterChain bean, Spring Boot auto-configuration backs off and lets you fully control the actuator access rules.
If you wish to configure custom security for HTTP endpoints (for example, to allow only users with a certain role to access them), Spring Boot provides some convenient RequestMatcher objects that you can use in combination with Spring Security.
A typical Spring Security configuration might look something like the following example:
code:typical/MySecurityConfiguration
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-restapi-docs}[HTML] or {spring-boot-actuator-restapi-pdfdocs}[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 configprop:management.endpoints.web.exposure.include[] property, as follows:
management:
endpoints:
web:
exposure:
include: "*"Additionally, if Spring Security is present, you would need to add custom security configuration that allows unauthenticated access to the endpoints, as the following example shows:
code:exposeall/MySecurityConfiguration
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Note
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In both of the preceding examples, the configuration applies only to the actuator endpoints.
Since Spring Boot’s security configuration backs off completely in the presence of any SecurityFilterChain bean, you need to configure an additional SecurityFilterChain bean with rules that apply to the rest of the application.
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Since Spring Boot relies on Spring Security’s defaults, CSRF protection is turned on by default.
This means that the actuator endpoints that require a POST (shutdown and loggers endpoints), a PUT, or a DELETE get a 403 (forbidden) error when the default security configuration is in use.
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Note
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We recommend disabling CSRF protection completely only if you are creating a service that is used by non-browser clients. |
You can find additional information about CSRF protection in the {spring-security-docs}/features/exploits/csrf.html[Spring Security Reference Guide].
Endpoints automatically cache responses to read operations that do not take any parameters.
To configure the amount of time for which an endpoint caches 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:
management:
endpoint:
beans:
cache:
time-to-live: "10s"|
Note
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The management.endpoint.<name> prefix uniquely identifies the endpoint that is being configured.
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A “discovery page” is added with links to all the endpoints.
The “discovery page” is available on /actuator by default.
To disable the “discovery page”, add the following property to your application properties:
management:
endpoints:
web:
discovery:
enabled: falseWhen 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, 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.
Cross-origin resource sharing (CORS) is a 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, you can configure Actuator’s web endpoints to support such scenarios.
CORS support is disabled by default and is only enabled once you have set the configprop:management.endpoints.web.cors.allowed-origins[] property.
The following configuration permits GET and POST calls from the example.com domain:
management:
endpoints:
web:
cors:
allowed-origins: "https://example.com"
allowed-methods: "GET,POST"|
Tip
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See {spring-boot-actuator-autoconfigure-module-code}/endpoint/web/CorsEndpointProperties.java[CorsEndpointProperties] for a complete list of options.
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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.
Endpoints can be exposed over HTTP by using Jersey, Spring MVC, or Spring WebFlux.
If both Jersey and Spring MVC are available, Spring MVC is used.
The following example exposes a read operation that returns a custom object:
code:MyEndpoint
You can also write technology-specific endpoints by using @JmxEndpoint or @WebEndpoint.
These endpoints are restricted to their respective technologies.
For example, @WebEndpoint is exposed only over HTTP and not over JMX.
You can write technology-specific extensions by using @EndpointWebExtension and @EndpointJmxExtension.
These annotations let you provide technology-specific operations to augment an existing endpoint.
Finally, if you need access to web-framework-specific functionality, you can implement servlet or Spring @Controller and @RestController endpoints at the cost of them not being available over JMX or when using a different web framework.
Operations on an endpoint receive input through their parameters.
When exposed over the web, the values for these parameters are taken from the URL’s query parameters and from the JSON request body.
When exposed over JMX, the parameters are mapped to the parameters of the MBean’s operations.
Parameters are required by default.
They can be made optional by annotating them with either @javax.annotation.Nullable or @org.springframework.lang.Nullable.
You can map each root property in the JSON request body to a parameter of the endpoint. Consider the following JSON request body:
{
"name": "test",
"counter": 42
}You can use this to invoke a write operation that takes String name and int counter parameters, as the following example shows:
code:../MyEndpoint
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Tip
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Because endpoints are technology agnostic, only simple types can be specified in the method signature.
In particular, declaring a single parameter with a CustomData type that defines a name and counter properties is not supported.
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Note
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To let the input be mapped to the operation method’s parameters, Java code that implements an endpoint should be compiled with -parameters, and Kotlin code that implements an endpoint should be compiled with -java-parameters.
This will happen automatically if you use Spring Boot’s Gradle plugin or if you use Maven and spring-boot-starter-parent.
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The parameters passed to endpoint operation methods are, if necessary, automatically converted to the required type.
Before calling an operation method, the input received over JMX or HTTP is converted to the required types by using an instance of ApplicationConversionService as well as any Converter or GenericConverter beans qualified with @EndpointConverter.
Operations on an @Endpoint, @WebEndpoint, or @EndpointWebExtension are automatically exposed over HTTP using Jersey, Spring MVC, or Spring WebFlux.
If both Jersey and Spring MVC are available, Spring MVC is used.
A request predicate is automatically generated for each operation on a web-exposed endpoint.
The path of the predicate is determined by the ID of the endpoint and the base path of the web-exposed endpoints.
The default base path is /actuator.
For example, an endpoint with an ID of sessions uses /actuator/sessions as its path in the predicate.
You can further customize the path by annotating one or more parameters of the operation method with @Selector.
Such a parameter is added to the path predicate as a path variable.
The variable’s value is passed into the operation method when the endpoint operation is invoked.
If you want to capture all remaining path elements, you can add @Selector(Match=ALL_REMAINING) to the last parameter and make it a type that is conversion-compatible with a String[].
The HTTP method of the predicate is determined by the operation type, as shown in the following table:
| Operation | HTTP method |
|---|---|
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For a @WriteOperation (HTTP POST) that uses the request body, the consumes clause of the predicate is application/vnd.spring-boot.actuator.v2+json, application/json.
For all other operations, the consumes clause is empty.
The produces clause of the predicate can be determined by the produces attribute of the @DeleteOperation, @ReadOperation, and @WriteOperation annotations.
The attribute is optional.
If it is not used, the produces clause is determined automatically.
If the operation method returns void or Void, the produces clause is empty.
If the operation method returns a org.springframework.core.io.Resource, the produces clause is application/octet-stream.
For all other operations, the produces clause is application/vnd.spring-boot.actuator.v2+json, application/json.
The default response status for an endpoint operation depends on the operation type (read, write, or delete) and what, if anything, the operation returns.
If a @ReadOperation returns a value, the response status will be 200 (OK).
If it does not return a value, the response status will be 404 (Not Found).
If a @WriteOperation or @DeleteOperation returns a value, the response status will be 200 (OK).
If it does not return a value, the response status will be 204 (No Content).
If an operation is invoked without a required parameter or with a parameter that cannot be converted to the required type, the operation method is not called, and the response status will be 400 (Bad Request).
You can use an HTTP range request to request part of an HTTP resource.
When using Spring MVC or Spring Web Flux, operations that return a org.springframework.core.io.Resource automatically support range requests.
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Note
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Range requests are not supported when using Jersey. |
An operation on a web endpoint or a web-specific endpoint extension can receive the current java.security.Principal or org.springframework.boot.actuate.endpoint.SecurityContext as a method parameter.
The former is typically used in conjunction with @Nullable to provide different behavior for authenticated and unauthenticated users.
The latter is typically used to perform authorization checks by using its isUserInRole(String) method.
A servlet can be exposed as an endpoint by implementing a class annotated with @ServletEndpoint that also implements Supplier<EndpointServlet>.
Servlet endpoints provide deeper integration with the servlet container but at the expense of portability.
They are intended to be used to expose an existing servlet as an endpoint.
For new endpoints, the @Endpoint and @WebEndpoint annotations should be preferred whenever possible.
You can use @ControllerEndpoint and @RestControllerEndpoint to implement an endpoint that is exposed only by Spring MVC or Spring WebFlux.
Methods are mapped by using the standard annotations for Spring MVC and Spring WebFlux, such as @RequestMapping and @GetMapping, with the endpoint’s ID being used as a prefix for the path.
Controller endpoints provide deeper integration with Spring’s web frameworks but at the expense of portability.
The @Endpoint and @WebEndpoint annotations should be preferred whenever possible.
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 configprop:management.endpoint.health.show-details[] and configprop:management.endpoint.health.show-components[] properties, which can be configured with one of the following values:
| Name | Description |
|---|---|
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Details are never shown. |
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Details are shown only to authorized users.
Authorized roles can be configured by using |
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Details are shown to all users. |
The default value is never.
A user is considered to be authorized when they are in one or more of the endpoint’s roles.
If the endpoint has no configured roles (the default), all authenticated users are considered to be authorized.
You can configure the roles by using the configprop:management.endpoint.health.roles[] property.
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Note
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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.
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Health information is collected from the content of a {spring-boot-actuator-module-code}/health/HealthContributorRegistry.java[HealthContributorRegistry] (by default, all {spring-boot-actuator-module-code}/health/HealthContributor.java[HealthContributor] instances defined in your ApplicationContext).
Spring Boot includes a number of auto-configured HealthContributors, and you can also write your own.
A HealthContributor can be either a HealthIndicator or a CompositeHealthContributor.
A HealthIndicator provides actual health information, including a Status.
A CompositeHealthContributor provides a composite of other HealthContributors.
Taken together, contributors form a tree structure to represent the overall system health.
By default, the final system health is derived by a StatusAggregator, 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 StatusAggregator, an UNKNOWN status is used.
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Tip
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You can use the HealthContributorRegistry to register and unregister health indicators at runtime.
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When appropriate, Spring Boot auto-configures the HealthIndicators listed in the following table.
You can also enable or disable selected indicators by configuring management.health.key.enabled,
with the key listed in the following table:
| Key | Name | Description |
|---|---|---|
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{spring-boot-actuator-module-code}/cassandra/CassandraDriverHealthIndicator.java[ |
Checks that a Cassandra database is up. |
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{spring-boot-actuator-module-code}/couchbase/CouchbaseHealthIndicator.java[ |
Checks that a Couchbase cluster is up. |
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{spring-boot-actuator-module-code}/jdbc/DataSourceHealthIndicator.java[ |
Checks that a connection to |
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{spring-boot-actuator-module-code}/system/DiskSpaceHealthIndicator.java[ |
Checks for low disk space. |
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{spring-boot-actuator-module-code}/elasticsearch/ElasticsearchRestHealthIndicator.java[ |
Checks that an Elasticsearch cluster is up. |
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{spring-boot-actuator-module-code}/hazelcast/HazelcastHealthIndicator.java[ |
Checks that a Hazelcast server is up. |
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{spring-boot-actuator-module-code}/influx/InfluxDbHealthIndicator.java[ |
Checks that an InfluxDB server is up. |
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{spring-boot-actuator-module-code}/jms/JmsHealthIndicator.java[ |
Checks that a JMS broker is up. |
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{spring-boot-actuator-module-code}/ldap/LdapHealthIndicator.java[ |
Checks that an LDAP server is up. |
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{spring-boot-actuator-module-code}/mail/MailHealthIndicator.java[ |
Checks that a mail server is up. |
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{spring-boot-actuator-module-code}/data/mongo/MongoHealthIndicator.java[ |
Checks that a Mongo database is up. |
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{spring-boot-actuator-module-code}/neo4j/Neo4jHealthIndicator.java[ |
Checks that a Neo4j database is up. |
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{spring-boot-actuator-module-code}/health/PingHealthIndicator.java[ |
Always responds with |
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{spring-boot-actuator-module-code}/amqp/RabbitHealthIndicator.java[ |
Checks that a Rabbit server is up. |
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{spring-boot-actuator-module-code}/data/redis/RedisHealthIndicator.java[ |
Checks that a Redis server is up. |
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Tip
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You can disable them all by setting the configprop:management.health.defaults.enabled[] property. |
Additional HealthIndicators are available but are not enabled by default:
| Key | Name | Description |
|---|---|---|
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{spring-boot-actuator-module-code}/availability/LivenessStateHealthIndicator.java[ |
Exposes the “Liveness” application availability state. |
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{spring-boot-actuator-module-code}/availability/ReadinessStateHealthIndicator.java[ |
Exposes the “Readiness” application availability state. |
To provide custom health information, you can register Spring beans that implement the {spring-boot-actuator-module-code}/health/HealthIndicator.java[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:
code:MyHealthIndicator
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Note
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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.
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Tip
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Health indicators are usually called over HTTP and need to respond before any connection timeouts. Spring Boot will log a warning message for any health indicator that takes longer than 10 seconds to respond. If you want to configure this threshold, you can use the configprop:management.endpoint.health.logging.slow-indicator-threshold[] property. |
In addition to Spring Boot’s predefined {spring-boot-actuator-module-code}/health/Status.java[Status] types, Health can return a custom Status that represents a new system state.
In such cases, you also need to provide a custom implementation of the {spring-boot-actuator-module-code}/health/StatusAggregator.java[StatusAggregator] interface, or you must configure the default implementation by using the configprop:management.endpoint.health.status.order[] configuration property.
For example, assume a new Status with a code of FATAL is being used in one of your HealthIndicator implementations.
To configure the severity order, add the following property to your application properties:
management:
endpoint:
health:
status:
order: "fatal,down,out-of-service,unknown,up"The HTTP status code in the response reflects the overall health status.
By default, OUT_OF_SERVICE and DOWN map to 503.
Any unmapped health statuses, including UP, map to 200.
You might also want to register custom status mappings if you access the health endpoint over HTTP.
Configuring a custom mapping disables the defaults mappings for DOWN and OUT_OF_SERVICE.
If you want to retain the default mappings, you must explicitly configure them, alongside any custom mappings.
For example, the following property maps FATAL to 503 (service unavailable) and retains the default mappings for DOWN and OUT_OF_SERVICE:
management:
endpoint:
health:
status:
http-mapping:
down: 503
fatal: 503
out-of-service: 503|
Tip
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If you need more control, you can define your own HttpCodeStatusMapper bean.
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The following table shows the default status mappings for the built-in statuses:
| Status | Mapping |
|---|---|
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No mapping by default, so HTTP status is |
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No mapping by default, so HTTP status is |
For reactive applications, such as those that use Spring WebFlux, ReactiveHealthContributor provides a non-blocking contract for getting application health.
Similar to a traditional HealthContributor, health information is collected from the content of a {spring-boot-actuator-module-code}/health/ReactiveHealthContributorRegistry.java[ReactiveHealthContributorRegistry] (by default, all {spring-boot-actuator-module-code}/health/HealthContributor.java[HealthContributor] and {spring-boot-actuator-module-code}/health/ReactiveHealthContributor.java[ReactiveHealthContributor] instances defined in your ApplicationContext).
Regular HealthContributors that do not check against a reactive API are executed on the elastic scheduler.
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Tip
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In a reactive application, you should use the ReactiveHealthContributorRegistry to register and unregister health indicators at runtime.
If you need to register a regular HealthContributor, you should wrap it with ReactiveHealthContributor#adapt.
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To provide custom health information from a reactive API, you can register Spring beans that implement the {spring-boot-actuator-module-code}/health/ReactiveHealthIndicator.java[ReactiveHealthIndicator] interface.
The following code shows a sample ReactiveHealthIndicator implementation:
code:MyReactiveHealthIndicator
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Tip
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To handle the error automatically, consider extending from AbstractReactiveHealthIndicator.
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When appropriate, Spring Boot auto-configures the following ReactiveHealthIndicators:
| Key | Name | Description |
|---|---|---|
|
{spring-boot-actuator-module-code}/cassandra/CassandraDriverReactiveHealthIndicator.java[ |
Checks that a Cassandra database is up. |
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{spring-boot-actuator-module-code}/couchbase/CouchbaseReactiveHealthIndicator.java[ |
Checks that a Couchbase cluster is up. |
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{spring-boot-actuator-module-code}/data/elasticsearch/ElasticsearchReactiveHealthIndicator.java[ |
Checks that an Elasticsearch cluster is up. |
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{spring-boot-actuator-module-code}/data/mongo/MongoReactiveHealthIndicator.java[ |
Checks that a Mongo database is up. |
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{spring-boot-actuator-module-code}/neo4j/Neo4jReactiveHealthIndicator.java[ |
Checks that a Neo4j database is up. |
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{spring-boot-actuator-module-code}/data/redis/RedisReactiveHealthIndicator.java[ |
Checks that a Redis server is up. |
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Tip
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If necessary, reactive indicators replace the regular ones.
Also, any HealthIndicator that is not handled explicitly is wrapped automatically.
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It is sometimes useful to organize health indicators into groups that you can use for different purposes.
To create a health indicator group, you can use the management.endpoint.health.group.<name> property and specify a list of health indicator IDs to include or exclude.
For example, to create a group that includes only database indicators you can define the following:
management:
endpoint:
health:
group:
custom:
include: "db"You can then check the result by hitting http://localhost:8080/actuator/health/custom.
Similarly, to create a group that excludes the database indicators from the group and includes all the other indicators, you can define the following:
management:
endpoint:
health:
group:
custom:
exclude: "db"By default, groups inherit the same StatusAggregator and HttpCodeStatusMapper settings as the system health.
However, you can also define these on a per-group basis.
You can also override the show-details and roles properties if required:
management:
endpoint:
health:
group:
custom:
show-details: "when-authorized"
roles: "admin"
status:
order: "fatal,up"
http-mapping:
fatal: 500
out-of-service: 500|
Tip
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You can use @Qualifier("groupname") if you need to register custom StatusAggregator or HttpCodeStatusMapper beans for use with the group.
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A health group can also include/exclude a CompositeHealthContributor.
You can also include/exclude only a certain component of a CompositeHealthContributor.
This can be done using the fully qualified name of the component as follows:
management.endpoint.health.group.custom.include="test/primary"
management.endpoint.health.group.custom.exclude="test/primary/b"In the example above, the custom group will include the HealthContributor with the name primary which is a component of the composite test.
Here, primary itself is a composite and the HealthContributor with the name b will be excluded from the custom group.
Health groups can be made available at an additional path on either the main or management port. This is useful in cloud environments such as Kubernetes, where it is quite common to use a separate management port for the actuator endpoints for security purposes. Having a separate port could lead to unreliable health checks because the main application might not work properly even if the health check is successful. The health group can be configured with an additional path as follows:
management.endpoint.health.group.live.additional-path="server:/healthz"This would make the live health group available on the main server port at /healthz.
The prefix is mandatory and must be either server: (represents the main server port) or management: (represents the management port, if configured.)
The path must be a single path segment.
The DataSource health indicator shows the health of both standard data sources and routing data source beans.
The health of a routing data source includes the health of each of its target data sources.
In the health endpoint’s response, each of a routing data source’s targets is named by using its routing key.
If you prefer not to include routing data sources in the indicator’s output, set configprop:management.health.db.ignore-routing-data-sources[] to true.
Applications deployed on Kubernetes can provide information about their internal state with Container Probes. Depending on your Kubernetes configuration, the kubelet calls those probes and reacts to the result.
By default, Spring Boot manages your Application Availability State.
If deployed in a Kubernetes environment, actuator gathers the “Liveness” and “Readiness” information from the ApplicationAvailability interface and uses that information in dedicated health indicators: LivenessStateHealthIndicator and ReadinessStateHealthIndicator.
These indicators are shown on the global health endpoint ("/actuator/health").
They are also exposed as separate HTTP Probes by using health groups: "/actuator/health/liveness" and "/actuator/health/readiness".
You can then configure your Kubernetes infrastructure with the following endpoint information:
livenessProbe:
httpGet:
path: "/actuator/health/liveness"
port: <actuator-port>
failureThreshold: ...
periodSeconds: ...
readinessProbe:
httpGet:
path: "/actuator/health/readiness"
port: <actuator-port>
failureThreshold: ...
periodSeconds: ...|
Note
|
<actuator-port> should be set to the port that the actuator endpoints are available on.
It could be the main web server port or a separate management port if the "management.server.port" property has been set.
|
These health groups are automatically enabled only if the application runs in a Kubernetes environment. You can enable them in any environment by using the configprop:management.endpoint.health.probes.enabled[] configuration property.
|
Note
|
If an application takes longer to start than the configured liveness period, Kubernetes mentions the "startupProbe" as a possible solution.
Generally speaking, the "startupProbe" is not necessarily needed here, as the "readinessProbe" fails until all startup tasks are done.
This means your application will not receive traffic until it is ready.
However, if your application takes a long time to start, consider using a "startupProbe" to make sure that Kubernetes won’t kill your application while it is in the process of starting.
See the section that describes how probes behave during the application lifecycle.
|
If your Actuator endpoints are deployed on a separate management context, the endpoints do not use the same web infrastructure (port, connection pools, framework components) as the main application.
In this case, a probe check could be successful even if the main application does not work properly (for example, it cannot accept new connections).
For this reason, is it a good idea to make the liveness and readiness health groups available on the main server port.
This can be done by setting the following property:
management.endpoint.health.probes.add-additional-paths=trueThis would make liveness available at /livez and readiness at readyz on the main server port.
Actuator configures the “liveness” and “readiness” probes as Health Groups. This means that all the health groups features are available for them. You can, for example, configure additional Health Indicators:
management:
endpoint:
health:
group:
readiness:
include: "readinessState,customCheck"By default, Spring Boot does not add other health indicators to these groups.
The “liveness” probe should not depend on health checks for external systems. If the liveness state of an application is broken, Kubernetes tries to solve that problem by restarting the application instance. This means that if an external system (such as a database, a Web API, or an external cache) fails, Kubernetes might restart all application instances and create cascading failures.
As for the “readiness” probe, the choice of checking external systems must be made carefully by the application developers. For this reason, Spring Boot does not include any additional health checks in the readiness probe. If the readiness state of an application instance is unready, Kubernetes does not route traffic to that instance. Some external systems might not be shared by application instances, in which case they could be included in a readiness probe. Other external systems might not be essential to the application (the application could have circuit breakers and fallbacks), in which case they definitely should not be included. Unfortunately, an external system that is shared by all application instances is common, and you have to make a judgement call: Include it in the readiness probe and expect that the application is taken out of service when the external service is down or leave it out and deal with failures higher up the stack, perhaps by using a circuit breaker in the caller.
|
Note
|
If all instances of an application are unready, a Kubernetes Service with type=ClusterIP or NodePort does not accept any incoming connections.
There is no HTTP error response (503 and so on), since there is no connection.
A service with type=LoadBalancer might or might not accept connections, depending on the provider.
A service that has an explicit ingress also responds in a way that depends on the implementation — the ingress service itself has to decide how to handle the “connection refused” from downstream.
HTTP 503 is quite likely in the case of both load balancer and ingress.
|
Also, if an application uses Kubernetes autoscaling, it may react differently to applications being taken out of the load-balancer, depending on its autoscaler configuration.
An important aspect of the Kubernetes Probes support is its consistency with the application lifecycle.
There is a significant difference between the AvailabilityState (which is the in-memory, internal state of the application)
and the actual probe (which exposes that state).
Depending on the phase of application lifecycle, the probe might not be available.
Spring Boot publishes application events during startup and shutdown,
and probes can listen to such events and expose the AvailabilityState information.
The following tables show the AvailabilityState and the state of HTTP connectors at different stages.
When a Spring Boot application starts:
| Startup phase | LivenessState | ReadinessState | HTTP server | Notes |
|---|---|---|---|---|
Starting |
|
|
Not started |
Kubernetes checks the "liveness" Probe and restarts the application if it takes too long. |
Started |
|
|
Refuses requests |
The application context is refreshed. The application performs startup tasks and does not receive traffic yet. |
Ready |
|
|
Accepts requests |
Startup tasks are finished. The application is receiving traffic. |
When a Spring Boot application shuts down:
| Shutdown phase | Liveness State | Readiness State | HTTP server | Notes |
|---|---|---|---|---|
Running |
|
|
Accepts requests |
Shutdown has been requested. |
Graceful shutdown |
|
|
New requests are rejected |
If enabled, graceful shutdown processes in-flight requests. |
Shutdown complete |
N/A |
N/A |
Server is shut down |
The application context is closed and the application is shut down. |
|
Tip
|
See Kubernetes container lifecycle section for more information about Kubernetes deployment. |
Application information exposes various information collected from all {spring-boot-actuator-module-code}/info/InfoContributor.java[InfoContributor] beans defined in your ApplicationContext.
Spring Boot includes a number of auto-configured InfoContributor beans, and you can write your own.
When appropriate, Spring auto-configures the following InfoContributor beans:
| ID | Name | Description | Prerequisites |
|---|---|---|---|
|
{spring-boot-actuator-module-code}/info/BuildInfoContributor.java[ |
Exposes build information. |
A |
|
{spring-boot-actuator-module-code}/info/EnvironmentInfoContributor.java[ |
Exposes any property from the |
None. |
|
{spring-boot-actuator-module-code}/info/GitInfoContributor.java[ |
Exposes git information. |
A |
|
{spring-boot-actuator-module-code}/info/JavaInfoContributor.java[ |
Exposes Java runtime information. |
None. |
|
{spring-boot-actuator-module-code}/info/OsInfoContributor.java[ |
Exposes Operating System information. |
None. |
Whether an individual contributor is enabled is controlled by its management.info.<id>.enabled property.
Different contributors have different defaults for this property, depending on their prerequisites and the nature of the information that they expose.
With no prerequisites to indicate that they should be enabled, the env, java, and os contributors are disabled by default.
Each can be enabled by setting its management.info.<id>.enabled property to true.
The build and git info contributors are enabled by default.
Each can be disabled by setting its management.info.<id>.enabled property to false.
Alternatively, to disable every contributor that is usually enabled by default, set the configprop:management.info.defaults.enabled[] property to false.
When the env contributor is enabled, 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:
info:
app:
encoding: "UTF-8"
java:
source: "11"
target: "11"|
Tip
|
Rather than hardcoding those values, you could also expand info properties at build time. Assuming you use Maven, you could rewrite the preceding example as follows: info:
app:
encoding: "@project.build.sourceEncoding@"
java:
source: "@java.version@"
target: "@java.version@" |
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, you can use the info endpoint to expose these properties.
|
Tip
|
A GitProperties bean is auto-configured if a git.properties file is available at the root of the classpath.
See "how to generate git information" for more detail.
|
By default, the endpoint exposes git.branch, git.commit.id, and git.commit.time properties, if present.
If you do not want any of these properties in the endpoint response, they need to be excluded from the git.properties file.
If you want to display the full git information (that is, the full content of git.properties), use the configprop:management.info.git.mode[] property, as follows:
management:
info:
git:
mode: "full"To disable the git commit information from the info endpoint completely, set the configprop:management.info.git.enabled[] property to false, as follows:
management:
info:
git:
enabled: falseIf 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 "how to generate build information" for more details. |
The info endpoint publishes information about your Java runtime environment, see {spring-boot-module-api}/info/JavaInfo.html[JavaInfo] for more details.
The info endpoint publishes information about your Operating System, see {spring-boot-module-api}/info/OsInfo.html[OsInfo] for more details.
To provide custom application information, you can register Spring beans that implement the {spring-boot-actuator-module-code}/info/InfoContributor.java[InfoContributor] interface.
The following example contributes an example entry with a single value:
code:MyInfoContributor
If you reach the info endpoint, you should see a response that contains the following additional entry:
{
"example": {
"key" : "value"
}
}