Actuator endpoints overview in Spring Boot - Step-by-Step Execution

Concept Flow - Actuator endpoints overview

Start Spring Boot App

↓

Actuator Enabled?

No→No Endpoints Available

Yes↓

Expose Endpoints

↓

User Sends HTTP Request

↓

Match Endpoint

↓

Execute Endpoint Logic

↓

Return JSON Response

↓

User Sees Health, Metrics, Info, etc.

Shows how Spring Boot starts, enables actuator, exposes endpoints, handles requests, and returns info.

Execution Sample

Spring Boot

GET /actuator/health
GET /actuator/metrics
GET /actuator/info

User requests common actuator endpoints to get app health, metrics, and info.

Execution Table

Step	Action	Request URL	Endpoint Matched	Response Content
1	App starts with actuator enabled	-	-	-
2	User sends HTTP GET	/actuator/health	health	{"status":"UP"}
3	User sends HTTP GET	/actuator/metrics	metrics	{"mem.used":12345678}
4	User sends HTTP GET	/actuator/info	info	{"app":{"version":"1.0.0"}}
5	User sends HTTP GET	/actuator/env	env	{"propertySources":["..."]}
6	User sends HTTP GET	/actuator/unknown	none	{"error":"Not Found"}

💡 Requests stop after all actuator endpoints are demonstrated or unknown endpoint returns error.

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	After Step 5	After Step 6
App Status	Starting	Running	Running	Running	Running	Running
Last Request URL	-	/actuator/health	/actuator/metrics	/actuator/info	/actuator/env	/actuator/unknown
Last Endpoint Matched	-	health	metrics	info	env	none
Last Response	-	{"status":"UP"}	{"mem.used":12345678}	{"app":{"version":"1.0.0"}}	{"propertySources":["..."]}	{"error":"Not Found"}

Key Moments - 2 Insights

Why do some actuator endpoints return detailed info while others return errors?

Because only enabled and exposed endpoints respond with data; unknown or disabled endpoints return errors as shown in step 6 of the execution_table.

How does the app know which endpoint to run when a request comes in?

The app matches the request URL to known actuator endpoints like /health or /metrics, as shown in the 'Endpoint Matched' column in the execution_table.

Visual Quiz - 3 Questions

Look at the execution_table, what is the response content when the user requests /actuator/health?

A {"status":"UP"}

B {"mem.used":12345678}

C {"app":{"version":"1.0.0"}}

D {"error":"Not Found"}

💡 Hint

Check row 2 under 'Response Content' in the execution_table.

At which step does the app respond with an error because the endpoint is unknown?

A Step 4

B Step 6

C Step 3

D Step 2

💡 Hint

Look for the row where 'Endpoint Matched' is 'none' in the execution_table.

If actuator was disabled, what would happen when a user requests /actuator/health?

A Return health status JSON

B Return metrics JSON

C Return 'Not Found' error

D Return info JSON

💡 Hint

Refer to the concept_flow where actuator enabled check leads to no endpoints if disabled.

Concept Snapshot

Spring Boot Actuator exposes HTTP endpoints like /health, /metrics, /info.
App must enable actuator to expose these.
User sends HTTP GET requests to endpoints.
App matches URL, runs logic, returns JSON response.
Unknown endpoints return errors.
Useful for monitoring app health and info.

Full Transcript

Spring Boot Actuator is a tool that adds special HTTP endpoints to your app. When the app starts with actuator enabled, it exposes URLs like /actuator/health, /actuator/metrics, and /actuator/info. When a user sends a GET request to these URLs, the app matches the request to the correct endpoint, runs the code to gather data, and sends back a JSON response. For example, /actuator/health returns the app's health status as {"status":"UP"}. If the user requests an unknown endpoint, the app returns a 'Not Found' error. This helps developers and operators check the app's status and metrics easily.