Spring Boot Actuator without Spring Boot

Allthough it is not a good idea to use Spring Boot features without Spring Boot, it is possible!

For example, this Java configuration makes Spring Boot Actuator Metrics available without using Spring Boot:

import java.util.Collection;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.actuate.autoconfigure.EndpointAutoConfiguration;
import org.springframework.boot.actuate.autoconfigure.PublicMetricsAutoConfiguration;
import org.springframework.boot.actuate.endpoint.MetricsEndpoint;
import org.springframework.boot.actuate.endpoint.mvc.EndpointHandlerMapping;
import org.springframework.boot.actuate.endpoint.mvc.EndpointMvcAdapter;
import org.springframework.boot.actuate.endpoint.mvc.MvcEndpoint;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;

@Configuration
@Import({ EndpointAutoConfiguration.class, PublicMetricsAutoConfiguration.class })
public class SpringBootActuatorConfig {

    @Bean
    @Autowired
    public EndpointHandlerMapping endpointHandlerMapping(Collection<? extends MvcEndpoint> endpoints) {
        return new EndpointHandlerMapping(endpoints);
    }

    @Bean
    @Autowired
    public EndpointMvcAdapter metricsEndPoint(MetricsEndpoint delegate) {
        return new EndpointMvcAdapter(delegate);
    }
}

The Maven dependency:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-actuator</artifactId>
    <version>1.3.5.RELEASE</version>
</dependency>

First let's clarify that you cannot use Spring Boot Actuator without using Spring Boot.

I was wrong about not being able to it without Spring Boot. See @stefaan-neyts answer for an example of how to do it.

I created a sample project to show how you could convert a basic SpringMVC application using a minimal amount of Spring Boot auto-configuration.

Original source: http://www.mkyong.com/spring-mvc/gradle-spring-mvc-web-project-example

Converted source: https://github.com/Pytry/minimal-boot-actuator

I could have completely removed the dispatcher-servlet.xml and the web.xml files, but I kept them to show how to perform as minimal a change as possible and to simplify converting more complex projects.

Here is a list of steps I took to convert.

Conversion Process

• Add a Java Configuration file annotated with @SpringBootApplication
• Add the Application configuration file as a bean to the traditional xml configuration ( added it just after the context scan).

• Move view resolvers into Application java configuration.

  Alternatively, add the prefix and suffix to application.properties. You can then inject them with @Value in your application, or delete it entirely and just use the provided spring boot view resolver. I went with the former.

• Removed Default context listener from the spring context xml.

  This is important! Since spring boot will provide one you will get an "Error listener Start" exception if you do not.

• Add the spring boot plugin to your build script dependencies (I was using gradle)

• Add a mainClassName property to the build file, and set to an empty String (indicates not to create an executable).

• Modify dependencies for spring boot actuator

You can use actuator without spring boot. Add this to pom.xml

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-actuator</artifactId>
    <version>1.3.5.RELEASE</version>
</dependency>

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-web</artifactId>
    <version>4.3.5.RELEASE</version>
</dependency>

And then in your config class

@Configuration
@EnableWebMvc
@Import({
        EndpointAutoConfiguration.class , PublicMetricsAutoConfiguration.class , HealthIndicatorAutoConfiguration.class
})
public class MyActuatorConfig {

    @Bean
    @Autowired
    public EndpointHandlerMapping endpointHandlerMapping(Collection<? extends MvcEndpoint> endpoints) {
        return new EndpointHandlerMapping(endpoints);
    }

    @Bean
    @Autowired
    public EndpointMvcAdapter metricsEndPoint(MetricsEndpoint delegate) {
        return new EndpointMvcAdapter(delegate);
    }
}

And then you can see the metrics in your application

http://localhost:8085/metrics