Spring Boot Monitoring with Actuator Questions and Answers

Question 1

A developer wants to expose only the `health` and `info` Actuator endpoints over HTTP for external monitoring, while keeping all other endpoints hidden for security. Which configuration in `application.properties` achieves this?

Accepted Answer

management.endpoints.web.exposure.include=health,info

Answer

In Spring Boot Actuator, the `management.endpoints.web.exposure.include` property is used to explicitly list the endpoint IDs that should be exposed over HTTP. By default, only `health` and `info` are exposed. To be explicit and secure, setting this property to 'health,info' ensures that only these two are accessible via the web, overriding any other defaults or broad inclusions. The `exclude` property takes precedence over `include`, so excluding '*' would hide all endpoints.

Question 2

What is the primary role of Micrometer in the context of Spring Boot Actuator?

Accepted Answer

To provide a vendor-neutral application metrics facade.

Answer

Micrometer acts as a metrics collection facade, similar to how SLF4J is a facade for logging. It provides a common API to instrument application code for metrics (like timers, counters, and gauges) without tying the application to a specific monitoring system. Spring Boot Actuator uses Micrometer to gather metrics and can then export them to various systems like Prometheus, Datadog, or InfluxDB.

Question 3

An operations team needs to access Actuator endpoints on a separate, dedicated port (e.g., 9090) to simplify network firewall rules, keeping them separate from the main application port (e.g., 8080). Which property should be set in `application.properties`?

Accepted Answer

management.server.port=9090

Answer

The `management.server.port` property is specifically used to configure a separate HTTP port for the management endpoints provided by Actuator. This isolates management traffic from application traffic, which is a common practice for security and operational reasons. The `server.port` property configures the main application port.

Question 4

A developer needs to add a custom check to the `/actuator/health` endpoint to verify the status of a critical downstream microservice. Which of the following is the standard Spring Boot approach?

Accepted Answer

Create a bean that implements the `HealthIndicator` interface.

Answer

The standard, extensible way to add custom health checks to the `/actuator/health` endpoint is to define a Spring bean that implements the `HealthIndicator` interface. Spring Boot Actuator will automatically discover any `HealthIndicator` beans and aggregate their status into the main health endpoint's response.

Question 5

Which Actuator endpoint provides a detailed list of all Spring beans currently in the ApplicationContext, including their scope, type, and dependencies?

Accepted Answer

/actuator/beans

Answer

The `/actuator/beans` endpoint is designed to provide a comprehensive report of all beans configured in the Spring `ApplicationContext`. It details each bean's name, aliases, scope, type, resource location, and the other beans it depends on, making it a powerful tool for debugging dependency injection issues.

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Spring Boot Monitoring with Actuator Questions and Answers