Fluentd Events API

openapi: 3.1.0
info:
  title: Fluentd HTTP Input Events API
  description: The Fluentd HTTP Input plugin exposes an HTTP endpoint that accepts log records posted as JSON, MessagePack, or form-encoded data. It allows applications to send events to Fluentd over standard HTTP, making it accessible from any language or platform that can make HTTP requests. Events can be sent individually or in batches, and the tag routing system determines downstream processing pipelines.
  version: 1.0.0
  contact:
    name: Fluentd Community
    url: https://www.fluentd.org/community/
  termsOfService: https://www.fluentd.org/
servers:
- url: http://localhost:8888
  description: Default Fluentd HTTP Input Server
tags:
- name: Events
  description: Operations for posting log events and records to Fluentd via HTTP.
paths:
  /{tag}:
    post:
      operationId: postEvent
      summary: Fluentd Post a log event
      description: Posts a single log event to Fluentd with the specified tag. The tag determines which Fluentd match rules route the event downstream. The request body can be JSON, MessagePack, or form-encoded. When sending JSON, the Content-Type must be application/json. The time field can be supplied in the body or omitted to use the server receive time.
      tags:
      - Events
      parameters:
      - $ref: '#/components/parameters/tag'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/EventRecord'
            examples:
              simple:
                summary: Simple log record
                value:
                  json:
                    level: info
                    message: Application started
                    service: my-app
          application/x-www-form-urlencoded:
            schema:
              $ref: '#/components/schemas/FormEventRecord'
          application/msgpack:
            schema:
              $ref: '#/components/schemas/EventRecord'
      responses:
        '200':
          description: Event accepted successfully.
        '400':
          description: Bad request. The payload is malformed or missing required fields.
        '500':
          description: Internal server error. Fluentd failed to process the event.
  /{tag}.{format}:
    post:
      operationId: postEventWithFormat
      summary: Fluentd Post a log event with explicit format
      description: Posts a single log event to Fluentd with both a tag and an explicit format specifier in the path. The format segment can be 'json' or 'msgpack' and overrides Content-Type-based format detection. This is useful for clients that cannot set Content-Type headers correctly.
      tags:
      - Events
      parameters:
      - $ref: '#/components/parameters/tag'
      - $ref: '#/components/parameters/format'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/EventRecord'
          application/x-www-form-urlencoded:
            schema:
              $ref: '#/components/schemas/FormEventRecord'
      responses:
        '200':
          description: Event accepted successfully.
        '400':
          description: Bad request. The payload is malformed or missing required fields.
        '500':
          description: Internal server error. Fluentd failed to process the event.
components:
  parameters:
    format:
      name: format
      in: path
      required: true
      description: Explicit format specifier for the request body. Accepted values are 'json' and 'msgpack'.
      schema:
        type: string
        enum:
        - json
        - msgpack
    tag:
      name: tag
      in: path
      required: true
      description: The Fluentd tag for this event. Tags use dot-separated hierarchical notation (e.g., myapp.access, production.web.error) and are used by match directives to route events to outputs.
      schema:
        type: string
        example: myapp.access
  schemas:
    EventRecord:
      type: object
      description: A Fluentd log event record submitted via HTTP. The 'json' property wraps the actual log payload. An optional 'time' field sets the event timestamp; if omitted, Fluentd uses the server receive time.
      properties:
        json:
          type: object
          description: The log record payload as an arbitrary key-value object. All fields are application-defined and passed through to downstream outputs.
          additionalProperties: true
          example:
            level: info
            message: User login successful
            user_id: 42
        time:
          type: integer
          description: Unix epoch timestamp for the event in seconds. If omitted, the Fluentd server assigns the receive time.
          example: 1700000000
    FormEventRecord:
      type: object
      description: A Fluentd log event submitted as URL-encoded form data. Each form field becomes a key-value pair in the event record.
      additionalProperties:
        type: string
      example:
        level: warn
        message: Disk usage above 80%
        host: web-01
externalDocs:
  description: Fluentd HTTP Input Plugin Documentation
  url: https://docs.fluentd.org/input/http