Actuator endpoints overview in Spring Boot - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

What is the primary purpose of Spring Boot Actuator endpoints?

Spring Boot Actuator provides several endpoints. What is their main purpose?

A To serve static web pages for the application frontend.

B To expose operational information about the running application for monitoring and management.

C To handle user authentication and authorization.

D To compile and build the application during runtime.

💡 Hint

Think about what monitoring tools need from a running app.

Actuator endpoints provide details like health, metrics, and environment info to help monitor and manage the app.

❓ component_behavior

intermediate

What output does the /actuator/health endpoint produce by default?

Consider a default Spring Boot app with Actuator enabled. What is the typical JSON output of the /actuator/health endpoint?

A {"state":"running"}

B {"result":"healthy"}

C {"health":"OK"}

D {"status":"UP"}

💡 Hint

Look for the key that indicates overall system status.

The health endpoint returns a JSON with a status key showing the app health, usually "UP" if all is well.

📝 Syntax

advanced

Which configuration enables all Actuator endpoints in Spring Boot 3.x?

Given the following application.properties snippet, which option correctly enables all Actuator endpoints?

Spring Boot

management.endpoints.web.exposure.include=

A management.endpoints.web.exposure.include=*

B management.endpoints.web.exposure.include=health,info,metrics,env

C management.endpoints.web.exposure.include=all

D management.endpoints.web.exposure.include=enabled

💡 Hint

Use the wildcard symbol to include all endpoints.

Setting management.endpoints.web.exposure.include=* exposes all available endpoints.

❓ state_output

advanced

What is the output of /actuator/metrics/jvm.memory.used endpoint?

When you access /actuator/metrics/jvm.memory.used, what kind of data do you expect to see?

A {"name":"jvm.memory.used","measurements":[{"statistic":"VALUE","value":12345678.0}],"availableTags":[]}

B {"memoryUsed":"12345678"}

C {"metric":"memory","used":true}

D {"status":"UP"}

💡 Hint

Look for a JSON structure with name, measurements, and statistics.

The metrics endpoint returns detailed JSON including metric name and measurement values.

🔧 Debug

expert

Why does the /actuator/env endpoint return 404 error by default?

You try to access /actuator/env but get a 404 Not Found error. What is the most likely reason?

A The application does not have the Actuator dependency added.

B The env endpoint is deprecated and removed in Spring Boot 3.x.

C The env endpoint is not exposed by default and must be explicitly enabled in configuration.

D The server port is incorrect in the request URL.

💡 Hint

Check which endpoints are exposed by default and which require explicit enabling.

By default, only a few endpoints like health and info are exposed. Others like env need to be enabled explicitly.

Practice

1. What is the main purpose of Spring Boot Actuator endpoints?

easy

A. To handle user authentication and authorization

B. To serve static web content like images and CSS

C. To manage database connections automatically

D. To provide information about the application's health and status

Solution

1. Step 1: Understand Actuator endpoints role

   Actuator endpoints are designed to give quick info about the app's health and status.

2. Step 2: Compare with other options

   Authentication, database management, and static content serving are not the main roles of Actuator.

3. Final Answer:

   To provide information about the application's health and status -> Option D

4. Quick Check:

   Actuator endpoints = app health info [OK]

Hint: Remember: Actuator = app health and metrics info [OK]

Common Mistakes:

• Confusing Actuator with security features
• Thinking Actuator manages database connections
• Assuming Actuator serves static files

2. Which property enables the exposure of all Actuator endpoints in Spring Boot?

easy

A. management.endpoints.web.exposure.include=*

B. spring.boot.actuator.enabled=true

C. management.endpoint.health.enabled=true

D. server.port=8080

Solution

1. Step 1: Identify property to expose endpoints

   The property management.endpoints.web.exposure.include=* exposes all Actuator endpoints.

2. Step 2: Check other options

   spring.boot.actuator.enabled is not a valid property; health endpoint enabling is specific, and server.port sets the server port.

3. Final Answer:

   management.endpoints.web.exposure.include=* -> Option A

4. Quick Check:

   Expose all endpoints = management.endpoints.web.exposure.include=* [OK]

Hint: Use '*' in exposure.include to enable all endpoints [OK]

Common Mistakes:

• Using incorrect property names
• Confusing enabling endpoints with enabling server
• Trying to enable endpoints individually without exposure property

3. Given the following configuration:

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

Which endpoints will be accessible via HTTP?

medium

A. Only /health and /info endpoints

B. All Actuator endpoints

C. No endpoints are accessible

D. Only /metrics endpoint

Solution

1. Step 1: Read the exposure.include property

   The property lists health and info, so only these endpoints are exposed.

2. Step 2: Understand what exposure.include controls

   It controls which endpoints are accessible via HTTP; others remain hidden.

3. Final Answer:

   Only /health and /info endpoints -> Option A

4. Quick Check:

   Exposure include = health,info means only those endpoints [OK]

Hint: Check exposure.include list to know accessible endpoints [OK]

Common Mistakes:

• Assuming all endpoints are exposed by default
• Confusing exposure.include with enabling endpoints
• Thinking metrics endpoint is included without listing it

4. You configured management.endpoints.web.exposure.include=health,metrics but the /metrics endpoint returns 404. What is the likely cause?

medium

A. The metrics endpoint is disabled by default and needs explicit enabling

B. The health endpoint is conflicting with metrics

C. The application is missing the actuator dependency

D. The server port is incorrect

Solution

1. Step 1: Check if actuator dependency is present

   Without the actuator library, endpoints like /metrics won't exist, causing 404.

2. Step 2: Verify other options

   Metrics endpoint is enabled by exposure.include; health does not conflict; server port affects access but not endpoint existence.

3. Final Answer:

   The application is missing the actuator dependency -> Option C

4. Quick Check:

   Missing actuator dependency = 404 on endpoints [OK]

Hint: Always add actuator dependency to use Actuator endpoints [OK]

Common Mistakes:

• Assuming endpoints work without actuator dependency
• Blaming port or conflicts instead of missing library
• Thinking exposure.include enables endpoints without actuator

5. You want to monitor your Spring Boot app's health, info, and metrics endpoints but only expose health and info publicly. How do you configure this securely?

hard

A. Set management.endpoints.web.exposure.include=health,info,metrics and disable security

B. Set management.endpoints.web.exposure.include=health,info and secure /metrics with authentication

C. Expose all endpoints with * and rely on firewall rules

D. Disable all endpoints except metrics

Solution

1. Step 1: Expose only health and info endpoints publicly

   Use management.endpoints.web.exposure.include=health,info to expose only those endpoints.

2. Step 2: Secure metrics endpoint separately

   Keep metrics endpoint enabled internally and protect it with authentication or network rules.

3. Final Answer:

   Set management.endpoints.web.exposure.include=health,info and secure /metrics with authentication -> Option B

4. Quick Check:

   Expose only needed endpoints publicly, secure others [OK]

Hint: Expose only needed endpoints publicly; secure sensitive ones [OK]

Common Mistakes:

• Exposing all endpoints without security
• Disabling security to simplify access
• Exposing metrics publicly without protection