openapi: 3.1.0
info:
  title: Thanos Compact Alerts Blocks API
  description: The Thanos Compact HTTP API provides operational endpoints for the Compactor component, which runs as a singleton process applying Prometheus compaction procedures to TSDB blocks stored in object storage. It performs downsampling at 5-minute and 1-hour resolutions and enforces retention policies to reduce long-term storage costs.
  version: 0.35.0
  contact:
    name: Thanos Community
    url: https://thanos.io/
  license:
    name: Apache 2.0
    url: https://www.apache.org/licenses/LICENSE-2.0
servers:
- url: http://localhost:10902
  description: Default Thanos Compact HTTP endpoint
tags:
- name: Blocks
  description: Block metadata inspection and compaction status endpoints.
paths:
  /api/v1/blocks:
    get:
      operationId: listCompactBlocks
      summary: Thanos List Blocks in Object Storage
      description: Returns metadata for all TSDB blocks in the configured object storage bucket as seen by the Compactor. Useful for monitoring compaction progress, checking downsampling status, and verifying retention policy enforcement.
      tags:
      - Blocks
      parameters:
      - name: view
        in: query
        required: false
        description: Specifies which blocks to include in the response. Use 'all' to see all tracked blocks, or filter by compaction state.
        schema:
          type: string
          enum:
          - loaded
          - all
      responses:
        '200':
          description: Block metadata list
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/BlocksResponse'
        '500':
          description: Internal error retrieving block metadata
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
components:
  schemas:
    ErrorResponse:
      type: object
      description: Error response returned when a request cannot be processed.
      required:
      - status
      - error
      properties:
        status:
          type: string
          enum:
          - error
        error:
          type: string
          description: Human-readable error message.
    BlockMeta:
      type: object
      description: Metadata for a single TSDB block managed by the Compactor.
      required:
      - ulid
      - minTime
      - maxTime
      properties:
        ulid:
          type: string
          description: Unique identifier for the block.
          example: 01FHND2RNJHSZ7E7XFPVKH2JG
        minTime:
          type: integer
          format: int64
          description: Minimum timestamp in milliseconds for data in this block.
        maxTime:
          type: integer
          format: int64
          description: Maximum timestamp in milliseconds for data in this block.
        compaction:
          type: object
          description: Compaction metadata tracking the block's compaction history.
          properties:
            level:
              type: integer
              description: Compaction level. Raw blocks start at level 1; each compaction pass increments the level.
            sources:
              type: array
              description: ULIDs of source blocks merged to create this block.
              items:
                type: string
        thanos:
          type: object
          description: Thanos-specific extensions to block metadata.
          properties:
            labels:
              type: object
              additionalProperties:
                type: string
              description: External labels identifying the origin of this block.
            downsample:
              type: object
              description: Downsampling resolution information.
              properties:
                resolution:
                  type: integer
                  format: int64
                  description: Resolution in milliseconds. 0 for raw, 300000 for 5-minute, 3600000 for 1-hour downsampled data.
            source:
              type: string
              description: Thanos component that produced this block.
              enum:
              - sidecar
              - receive
              - ruler
              - compactor
              - unknown
    BlocksResponse:
      type: object
      description: Response containing metadata for TSDB blocks managed by the Compactor.
      properties:
        status:
          type: string
          description: Status of the response.
          enum:
          - success
          - error
        data:
          type: object
          description: Block metadata payload.
          properties:
            blocks:
              type: array
              description: List of block metadata entries.
              items:
                $ref: '#/components/schemas/BlockMeta'
            label:
              type: string
              description: External label identifying the object storage tenant.
externalDocs:
  description: Thanos Compact Documentation
  url: https://thanos.io/tip/components/compact.md/