This version is still in development and is not considered stable yet. For the latest stable version, please use Spring Boot 3.5.5!spring-doc.cn

Application Startup (`startup`)

The startup endpoint provides information about the application’s startup sequence.spring-doc.cn

Retrieving the Application Startup Steps

The application startup steps can either be retrieved as a snapshot (GET) or drained from the buffer (POST).spring-doc.cn

Retrieving a snapshot of the Application Startup Steps

To retrieve the steps recorded so far during the application startup phase, make a GET request to /actuator/startup, as shown in the following curl-based example:spring-doc.cn

$ curl 'http://localhost:8080/actuator/startup' -i -X GET

The resulting response is similar to the following:spring-doc.cn

HTTP/1.1 200 OK
Content-Type: application/vnd.spring-boot.actuator.v3+json
Content-Length: 892

{
  "springBootVersion" : "4.0.0-M2",
  "timeline" : {
    "events" : [ {
      "duration" : "PT0.000005249S",
      "endTime" : "2025-08-21T20:11:59.388358472Z",
      "startTime" : "2025-08-21T20:11:59.388353223Z",
      "startupStep" : {
        "id" : 3,
        "name" : "spring.beans.instantiate",
        "parentId" : 2,
        "tags" : [ {
          "key" : "beanName",
          "value" : "homeController"
        } ]
      }
    }, {
      "duration" : "PT0.000018204S",
      "endTime" : "2025-08-21T20:11:59.388363662Z",
      "startTime" : "2025-08-21T20:11:59.388345458Z",
      "startupStep" : {
        "id" : 2,
        "name" : "spring.boot.application.starting",
        "tags" : [ {
          "key" : "mainApplicationClass",
          "value" : "com.example.startup.StartupApplication"
        } ]
      }
    } ],
    "startTime" : "2025-08-21T20:11:59.141000292Z"
  }
}

Draining the Application Startup Steps

To drain and return the steps recorded so far during the application startup phase, make a POST request to /actuator/startup, as shown in the following curl-based example:spring-doc.cn

$ curl 'http://localhost:8080/actuator/startup' -i -X POST

The resulting response is similar to the following:spring-doc.cn

HTTP/1.1 200 OK
Content-Type: application/vnd.spring-boot.actuator.v3+json
Content-Length: 892

{
  "springBootVersion" : "4.0.0-M2",
  "timeline" : {
    "events" : [ {
      "duration" : "PT0.000269193S",
      "endTime" : "2025-08-21T20:11:59.345262006Z",
      "startTime" : "2025-08-21T20:11:59.344992813Z",
      "startupStep" : {
        "id" : 1,
        "name" : "spring.beans.instantiate",
        "parentId" : 0,
        "tags" : [ {
          "key" : "beanName",
          "value" : "homeController"
        } ]
      }
    }, {
      "duration" : "PT0.001276664S",
      "endTime" : "2025-08-21T20:11:59.345297011Z",
      "startTime" : "2025-08-21T20:11:59.344020347Z",
      "startupStep" : {
        "id" : 0,
        "name" : "spring.boot.application.starting",
        "tags" : [ {
          "key" : "mainApplicationClass",
          "value" : "com.example.startup.StartupApplication"
        } ]
      }
    } ],
    "startTime" : "2025-08-21T20:11:59.141000292Z"
  }
}

Response Structure

The response contains details of the application startup steps. The following table describes the structure of the response:spring-doc.cn

Path Type Description

Path	Type	Description
`springBootVersion`spring-doc.cn	`String`spring-doc.cn	Spring Boot version for this application.spring-doc.cn
`timeline.startTime`spring-doc.cn	`String`spring-doc.cn	Start time of the application.spring-doc.cn
`timeline.events`spring-doc.cn	`Array`spring-doc.cn	An array of steps collected during application startup so far.spring-doc.cn
`timeline.events.[].startTime`spring-doc.cn	`String`spring-doc.cn	The timestamp of the start of this event.spring-doc.cn
`timeline.events.[].endTime`spring-doc.cn	`String`spring-doc.cn	The timestamp of the end of this event.spring-doc.cn
`timeline.events.[].duration`spring-doc.cn	`String`spring-doc.cn	The precise duration of this event.spring-doc.cn
`timeline.events.[].startupStep.name`spring-doc.cn	`String`spring-doc.cn	The name of the StartupStep.spring-doc.cn
`timeline.events.[].startupStep.id`spring-doc.cn	`Number`spring-doc.cn	The id of this StartupStep.spring-doc.cn
`timeline.events.[].startupStep.parentId`spring-doc.cn	`Number`spring-doc.cn	The parent id for this StartupStep.spring-doc.cn
`timeline.events.[].startupStep.tags`spring-doc.cn	`Array`spring-doc.cn	An array of key/value pairs with additional step info.spring-doc.cn
`timeline.events.[].startupStep.tags[].key`spring-doc.cn	`String`spring-doc.cn	The key of the StartupStep Tag.spring-doc.cn
`timeline.events.[].startupStep.tags[].value`spring-doc.cn	`String`spring-doc.cn	The value of the StartupStep Tag.spring-doc.cn

springBootVersionspring-doc.cn

Stringspring-doc.cn

Spring Boot version for this application.spring-doc.cn

timeline.startTimespring-doc.cn

Stringspring-doc.cn

Start time of the application.spring-doc.cn

timeline.eventsspring-doc.cn

Arrayspring-doc.cn

An array of steps collected during application startup so far.spring-doc.cn

timeline.events.[].startTimespring-doc.cn

Stringspring-doc.cn

The timestamp of the start of this event.spring-doc.cn