Guide to Spring Boot Actuator ‘/Info’ Endpoint

In this tutorial, we plan to learn about Spring Boot Actuator and how to add custom information to the /info endpoint. We will need Java 8 or higher, Maven, and your favorite IDE as a prerequisite.

1. Adding Spring Boot Actuator Module

Spring Boot Actuator is a Spring Framework sub-project. It allows us to monitor our application, get information about the project, gather metrics, or just check the state of our application/database.

A very convenient part of the Actuator is that it provides all support out of the box without any additional configuration. All we need to do to access all the information is to add the following dependency in our pom.xml file:

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

2. Enabling ‘/info’ Endpoint

After adding the actuator dependency, the only remaining step is to enable the endpoints provided by him. Spring boot can provide information to any target type, such as JMX or Web. To use an endpoint:

• The endpoint must be enabled.
• Its exposure must be enabled for the target destination.

By default, all endpoints except /shutdown are enabled. For web exposure, only /health endpoint is enabled. So for a Spring boot web application, by default, only /health endpoint will be accessible from the browser, and other endpoints can be accessed using JMX.

To enable or disable an endpoint, we can use its 'management.endpoint.<id>.enabled' property and set it to true or false. And to enable and disable the exposure of an endpoint, use management.endpoints.web.exposure.include and management.endpoints.web.exposure.exclude property.

For web, /info endpoint is enabled by default, so we only need to enable its exposure.

management.endpoints.web.exposure.include=info

We can enable the exposure of multiple endpoints or all endpoints in the following way:

#Enable all endpoints
# management.endpoints.web.exposure.include = *

# Include only specific endpoints
management.endpoints.web.exposure.include = info, shutdown, beans 

Actuator endpoints usually contain some sensitive data about the application, so we should not expose them as public APIs and provide secure access.

3. Default Information Provided by ‘/info’ Endpoint

For our example, we will use the application from the article: Bootstrapping a REST API with Spring Boot. We will open the project and follow the steps from the article’s first point: add the Spring Boot Actuator dependency and enable the /info endpoint.

When we run the application, the Spring app tells us about the newly exposed endpoint i.e. /actuator

INFO 29776 --- [main] o.s.b.a.e.web.EndpointLinksResolver      : Exposing 1 endpoint(s) beneath base path '/actuator'

Now we can check the endpoint at the following path: /actuator/info. And we will see the following blank response by default because we did not configure any properties for the /info endpoint.

There are the following inbuilt contributors for application information. We must enable them to include that information in /info response.

• build: Exposes build information from META-INF/build-info.properties file
• env: Exposes any property from the Environment whose name starts with info.
• git: Exposes git information from git.properties in the classpath.
• java: Exposes Java runtime information.
• os: Exposes Operating System information.

management.info.env.enabled=true
management.info.build.enabled=true
management.info.git.enabled=true
management.info.java.enabled=true
management.info.os.enabled=true

4. Adding Custom Information to /info Endpoint

4.1. Using application.properties

If we want to add static information that would not be changed often, like the name or the description of the project, it’s a good idea to add some static properties.

All we need to do is to prefix the name of the property with “info.". We can also group the properties, giving them the same prefixes. We can see below how we added three new information to our endpoint: name of the project, description, and organization name:

management.endpoints.web.exposure.include = info

info.application.name = Actuator info
info.application.description= A demo Spring project with information
info.organization = How to do in Java

We can see how we grouped the application information together, prefixing both of them with “application.” And the result from our browser will be:

Also, we can add dynamic variables like the version of the application, port, java version, or any environment variables.

info.java-version = ${java.version}
info.java-vendor = ${java.vendor}

And our result will look like this:

4.2. Using InfoContributor Interface

We can use Info.Builder to build the information from various sources such as a database, remote API, environment variables, or even hardcoded values.

First of all, create a new class CustomInfoContributor that implements the InfoContributor interface. Now, override its contribute() function. A skeleton of a class would look like this:

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

@Component
public class CustomInfoContributor implements InfoContributor {

    @Override
    public void contribute(Info.Builder builder) {
    }
}

We can autowire any bean such as DAO, Properties etc, and use them to populate dynamic data in the custom information. In the following example, we are autowiring the Environment to get Spring runtime environment information and add it to our endpoint.

@Autowired
private Environment environment;

In contribute() function, we use the builder and will call the function addDetails() with the label and the value of the property. In our example, we will add two new details to our endpoint, one for the running port of the application and the other one for the list of the default running profiles. Our final class should look like this:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.actuate.info.Info;
import org.springframework.boot.actuate.info.InfoContributor;
import org.springframework.core.env.Environment;
import org.springframework.stereotype.Component;

@Component
public class CustomInfoContributor implements InfoContributor {

    @Autowired
    private Environment environment;

    @Override
    public void contribute(Info.Builder builder) {
        builder.withDetail("port", environment.getProperty("local.server.port"));
        builder.withDetail("profiles", environment.getDefaultProfiles());
    }
}

And if we check the endpoint we can see the newly added properties:

4.3. Adding Build Information using Spring Boot Maven Plugin

We can add build information and additional properties to our /info endpoint using Spring Boot Maven Plugin. Spring Boot Actuator will show build details if a proper META-INF/build-info.properties file is present.

The Spring Boot Maven plugin has a build-info goal to create this file. We should add the plugin to our pom.xml file and the build-info goal.

<plugins>
  <plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
    <version>2.7.3</version>
    <executions>
      <execution>
        <goals>
          <goal>build-info</goal>
        </goals>
      </execution>
    </executions>
  </plugin>
</plugins>  

After adding the plugin we can run the maven clean install command and rerun the project. Check the /info endpoint, and we will see that a new ” build ” section has been added automatically.

More than that, we can add more properties (static or dynamic) in the info endpoint by adding the properties in the <additionalProperties> tag.

<plugin>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-maven-plugin</artifactId>
  <version>2.7.3</version>
  <executions>
    <execution>
      <goals>
        <goal>build-info</goal>
      </goals>
      <configuration>
        <additionalProperties>
          <java.version>${java.version}</java.version>
          <project.version>${project.version}</project.version>
        </additionalProperties>
      </configuration>
    </execution>
  </executions>
</plugin>

Rebuild and run the application. The new properties will reflect the output.

We can customize even more by excluding unwanted build properties using the excludeProperty tag.

<excludeInfoProperties>
    <infoProperty>time</infoProperty>
</excludeInfoProperties>

After adding the configuration above the new response will look like this: The time property is no longer visible.

5. Conclusion

This Spring boot tutorial examined various methods to add custom data to our /info endpoint. This endpoint may provide very useful information about our project but may also be a sensitive endpoint that should not be exposed to everyone.

Happy Learning !!

Sourcecode on Github