Spring Boot Admin Server API

openapi: 3.1.0
info:
  title: Spring Boot Admin Server API
  description: >-
    REST API for the Spring Boot Admin server. Manages application registration,
    instance monitoring, Actuator endpoint proxying, and lifecycle event streaming.
    Spring Boot Admin is a community project by codecentric AG that provides a
    web UI for monitoring and managing Spring Boot applications via their Actuator
    endpoints.
  version: 3.3.0
  contact:
    name: codecentric AG
    url: https://github.com/codecentric/spring-boot-admin
  license:
    name: Apache 2.0
    url: https://www.apache.org/licenses/LICENSE-2.0
servers:
  - url: http://localhost:8080
    description: Local Spring Boot Admin server
tags:
  - name: Applications
    description: Application registration and management
  - name: Instances
    description: Application instance monitoring and management
  - name: Events
    description: Instance lifecycle event stream
paths:
  /applications:
    get:
      operationId: listApplications
      summary: List Registered Applications
      description: >-
        Returns all applications registered with the Spring Boot Admin server,
        grouped by application name. Each application may have multiple instances.
      tags:
        - Applications
      responses:
        '200':
          description: List of registered applications
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Application'
    post:
      operationId: registerApplication
      summary: Register Application
      description: >-
        Registers a new Spring Boot application with the Admin server. Typically
        called automatically by the spring-boot-admin-client dependency on startup.
      tags:
        - Applications
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ApplicationRegistration'
      responses:
        '201':
          description: Application registered successfully
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Instance'
        '400':
          description: Invalid registration payload
  /applications/{name}:
    get:
      operationId: getApplication
      summary: Get Application
      description: Returns all instances for a specific application grouped by name.
      tags:
        - Applications
      parameters:
        - name: name
          in: path
          required: true
          description: Application name
          schema:
            type: string
            example: my-spring-app
      responses:
        '200':
          description: Application with all instances
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Application'
        '404':
          description: Application not found
    delete:
      operationId: deregisterApplication
      summary: Deregister Application
      description: >-
        Deregisters all instances of the specified application from the Admin server.
      tags:
        - Applications
      parameters:
        - name: name
          in: path
          required: true
          description: Application name to deregister
          schema:
            type: string
      responses:
        '204':
          description: Application deregistered
        '404':
          description: Application not found
  /instances:
    get:
      operationId: listInstances
      summary: List All Instances
      description: >-
        Returns all registered application instances. Each instance represents
        a running Spring Boot application registered with the Admin server.
      tags:
        - Instances
      parameters:
        - name: application
          in: query
          required: false
          description: Filter instances by application name
          schema:
            type: string
      responses:
        '200':
          description: List of application instances
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Instance'
  /instances/{id}:
    get:
      operationId: getInstance
      summary: Get Instance
      description: Returns details for a specific application instance by its ID.
      tags:
        - Instances
      parameters:
        - name: id
          in: path
          required: true
          description: Instance ID (assigned by Admin server on registration)
          schema:
            type: string
            example: abc123def456
      responses:
        '200':
          description: Instance details
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Instance'
        '404':
          description: Instance not found
    delete:
      operationId: deregisterInstance
      summary: Deregister Instance
      description: Deregisters a specific application instance from the Admin server.
      tags:
        - Instances
      parameters:
        - name: id
          in: path
          required: true
          description: Instance ID to deregister
          schema:
            type: string
      responses:
        '204':
          description: Instance deregistered
        '404':
          description: Instance not found
  /instances/{id}/actuator:
    get:
      operationId: getInstanceActuatorEndpoints
      summary: Get Instance Actuator Endpoints
      description: >-
        Returns the list of Actuator endpoints available for a specific instance,
        as discovered from the instance's /actuator endpoint.
      tags:
        - Instances
      parameters:
        - name: id
          in: path
          required: true
          description: Instance ID
          schema:
            type: string
      responses:
        '200':
          description: Available Actuator endpoints
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ActuatorEndpoints'
        '404':
          description: Instance not found
  /instances/{id}/actuator/health:
    get:
      operationId: getInstanceHealth
      summary: Get Instance Health
      description: Proxies the health Actuator endpoint for the specified instance.
      tags:
        - Instances
      parameters:
        - name: id
          in: path
          required: true
          description: Instance ID
          schema:
            type: string
      responses:
        '200':
          description: Instance health status
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HealthResponse'
        '404':
          description: Instance not found
        '503':
          description: Instance is unhealthy
  /instances/{id}/actuator/info:
    get:
      operationId: getInstanceInfo
      summary: Get Instance Info
      description: Proxies the info Actuator endpoint for the specified instance.
      tags:
        - Instances
      parameters:
        - name: id
          in: path
          required: true
          description: Instance ID
          schema:
            type: string
      responses:
        '200':
          description: Instance application info
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '404':
          description: Instance not found
  /instances/{id}/actuator/metrics:
    get:
      operationId: getInstanceMetrics
      summary: Get Instance Metrics
      description: Proxies the metrics Actuator endpoint for the specified instance.
      tags:
        - Instances
      parameters:
        - name: id
          in: path
          required: true
          description: Instance ID
          schema:
            type: string
      responses:
        '200':
          description: Available metrics for this instance
          content:
            application/json:
              schema:
                type: object
                properties:
                  names:
                    type: array
                    items:
                      type: string
        '404':
          description: Instance not found
  /instances/{id}/actuator/env:
    get:
      operationId: getInstanceEnvironment
      summary: Get Instance Environment
      description: Proxies the env Actuator endpoint for the specified instance.
      tags:
        - Instances
      parameters:
        - name: id
          in: path
          required: true
          description: Instance ID
          schema:
            type: string
      responses:
        '200':
          description: Instance environment properties
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '404':
          description: Instance not found
  /instances/{id}/actuator/loggers:
    get:
      operationId: getInstanceLoggers
      summary: Get Instance Loggers
      description: Proxies the loggers Actuator endpoint for the specified instance.
      tags:
        - Instances
      parameters:
        - name: id
          in: path
          required: true
          description: Instance ID
          schema:
            type: string
      responses:
        '200':
          description: Logger configuration for this instance
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '404':
          description: Instance not found
    post:
      operationId: setInstanceLoggerLevel
      summary: Set Instance Logger Level
      description: >-
        Proxies a POST to the loggers Actuator endpoint to change a logger level
        at runtime on the specified instance.
      tags:
        - Instances
      parameters:
        - name: id
          in: path
          required: true
          description: Instance ID
          schema:
            type: string
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                configuredLevel:
                  type: string
                  description: Log level to set
                  enum: [TRACE, DEBUG, INFO, WARN, ERROR, FATAL, OFF]
      responses:
        '204':
          description: Logger level updated
        '404':
          description: Instance not found
  /instances/events:
    get:
      operationId: streamInstanceEvents
      summary: Stream Instance Events
      description: >-
        Server-Sent Events (SSE) stream of all instance lifecycle events.
        Events include REGISTERED, DEREGISTERED, STATUS_CHANGED, INFO_CHANGED,
        and ENDPOINTS_DETECTED.
      tags:
        - Events
      responses:
        '200':
          description: SSE event stream of instance lifecycle events
          content:
            text/event-stream:
              schema:
                $ref: '#/components/schemas/InstanceEvent'
components:
  schemas:
    ApplicationRegistration:
      type: object
      description: Payload to register a Spring Boot application with the Admin server
      required:
        - name
        - managementUrl
        - healthUrl
        - serviceUrl
      properties:
        name:
          type: string
          description: Application name (typically spring.application.name)
          example: my-spring-app
        managementUrl:
          type: string
          description: URL of the management (Actuator) endpoint base
          example: http://localhost:8081/actuator
        healthUrl:
          type: string
          description: URL of the health endpoint
          example: http://localhost:8081/actuator/health
        serviceUrl:
          type: string
          description: URL of the service root
          example: http://localhost:8081
        metadata:
          type: object
          description: Additional metadata key-value pairs
          additionalProperties:
            type: string
    Application:
      type: object
      description: A logical grouping of application instances sharing the same name
      properties:
        name:
          type: string
          description: Application name
          example: my-spring-app
        instances:
          type: array
          description: Running instances of this application
          items:
            $ref: '#/components/schemas/Instance'
        status:
          type: string
          description: Aggregated status across all instances
          enum: [UP, DOWN, OUT_OF_SERVICE, UNKNOWN, RESTRICTED]
    Instance:
      type: object
      description: A single registered Spring Boot application instance
      properties:
        id:
          type: string
          description: Unique instance identifier assigned by Admin server
          example: abc123def456
        version:
          type: integer
          description: Optimistic locking version
        registration:
          $ref: '#/components/schemas/ApplicationRegistration'
        registered:
          type: boolean
          description: Whether the instance is currently registered
        statusInfo:
          $ref: '#/components/schemas/StatusInfo'
        statusTimestamp:
          type: string
          format: date-time
          description: Timestamp of the last status change
        info:
          type: object
          description: Application info collected from the /info Actuator endpoint
          additionalProperties: true
        endpoints:
          type: array
          description: Available Actuator endpoints for this instance
          items:
            type: object
            properties:
              id:
                type: string
                description: Endpoint ID (health, metrics, loggers, etc.)
              url:
                type: string
                description: Endpoint URL
        buildVersion:
          type: string
          description: Application build version from /info
          nullable: true
        tags:
          type: object
          description: Custom tags for this instance
          additionalProperties:
            type: string
    StatusInfo:
      type: object
      description: Status information for an application instance
      properties:
        status:
          type: string
          description: Current instance status
          enum: [UP, DOWN, OUT_OF_SERVICE, UNKNOWN, RESTRICTED, OFFLINE]
        details:
          type: object
          description: Additional status details from the health endpoint
          additionalProperties: true
    ActuatorEndpoints:
      type: object
      description: Available Actuator endpoints discovered for an instance
      properties:
        _links:
          type: object
          description: HATEOAS links to available endpoints
          additionalProperties:
            type: object
            properties:
              href:
                type: string
              templated:
                type: boolean
    HealthResponse:
      type: object
      description: Health status from a proxied instance health endpoint
      properties:
        status:
          type: string
          description: Health status
          enum: [UP, DOWN, OUT_OF_SERVICE, UNKNOWN]
        components:
          type: object
          description: Component health details
          additionalProperties:
            type: object
            properties:
              status:
                type: string
              details:
                type: object
                additionalProperties: true
    InstanceEvent:
      type: object
      description: A lifecycle event for an application instance (delivered via SSE)
      properties:
        instance:
          type: string
          description: Instance ID this event is about
          example: abc123def456
        version:
          type: integer
          description: Event version number (monotonically increasing)
        timestamp:
          type: string
          format: date-time
          description: When this event occurred
        type:
          type: string
          description: Event type
          enum:
            - REGISTERED
            - DEREGISTERED
            - STATUS_CHANGED
            - INFO_CHANGED
            - ENDPOINTS_DETECTED
        statusInfo:
          $ref: '#/components/schemas/StatusInfo'
        info:
          type: object
          description: Updated info payload (for INFO_CHANGED events)
          additionalProperties: true