> ## Documentation Index
> Fetch the complete documentation index at: https://headgate.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Change a fleet-wide rate limit at runtime.

> The flagship feature of this system is a shared rate limit, and the first version
of this API could only display it. During an incident the operator's action is to
raise, lower, or drain a limit — and if that requires a redeploy, the honest
summary is that the feature does not exist operationally. River UI edits queue
concurrency from its queue detail page; this is the equivalent for the gate.




## OpenAPI

````yaml /api/headgate.openapi.yaml put /rate-classes/{name}
openapi: 3.1.0
info:
  title: headgate control API
  version: 0.1.0
  description: >
    The web UI is one client of this control API and gets no

    privileged access — asynqmon reads Redis directly, which is why its
    compatibility

    note is three minor versions stale.


    Both the Go and Rust implementations serve this spec, and the conformance
    suite

    asserts identical responses. Every list endpoint is bounded to prevent
    inspection

    from becoming an unbounded store operation: asynq's

    GetQueueInfo is O(number of groups) and has pinned Redis CPU for seconds in

    production. Monitoring caused the outage.


    DERIVED FROM THE ARCHITECTURE, NOT FROM A PREDECESSOR'S UI. The first draft
    of this

    spec was the asynq Inspector surface -- list by state, act on one job, pause
    a queue

    -- with new nouns bolted on. That inherited three problems: it omitted bulk

    operations, history, and enqueue (which asynq and apalis-board respectively
    DO have),

    and more importantly it had no endpoint for the question this system's own
    design

    creates. When dequeue is an admission decision, the operator's first
    question is not

    "what is in the queue" but "why is THIS job not running" -- see
    /jobs/{id}/admission.

    No predecessor needs that endpoint because no predecessor has a gate.
servers:
  - url: /api/v1
security: []
paths:
  /rate-classes/{name}:
    put:
      summary: Change a fleet-wide rate limit at runtime.
      description: >
        The flagship feature of this system is a shared rate limit, and the
        first version

        of this API could only display it. During an incident the operator's
        action is to

        raise, lower, or drain a limit — and if that requires a redeploy, the
        honest

        summary is that the feature does not exist operationally. River UI edits
        queue

        concurrency from its queue detail page; this is the equivalent for the
        gate.
      parameters:
        - $ref: '#/components/parameters/Name'
        - $ref: '#/components/parameters/IdempotencyKey'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                limit:
                  type: integer
                window_ms:
                  type: integer
                burst:
                  type: integer
                paused:
                  type: boolean
                  description: Admit nothing in this class. The kill switch.
      responses:
        '200':
          description: Updated
components:
  parameters:
    Name:
      name: name
      in: path
      required: true
      schema:
        type: string
    IdempotencyKey:
      name: Idempotency-Key
      in: header
      required: true
      schema:
        type: string
      description: >
        Required on every mutating request. A double-clicked Retry, or a proxy
        retrying a

        POST, must not enqueue the job twice. Keys are retained long enough to
        cover a

        client retry window and the response is replayed verbatim.

````