Flow Example

In this configuration:

• API requests to api.website.com/* are queued with a limit of 10 requests per second.
• Requests are prioritized based on the x-lunar-consumer-tag header, where production traffic gets higher priority (1) over staging traffic (2).
• If the queue is full or a request is delayed beyond the defined TTL (12 seconds), the system returns a 429 HTTP status code with the message: "Too many requests. Please try again later."

Flow Configuration

/etc/lunar-proxy/flows/flow.yaml

name: PriorityQueueFlow

filter:
  url: api.website.com/*

processors:
  QueueLimiter:
    processor: Queue
    parameters:
      - key: quota_id
        value: MyQuota
      - key: ttl_seconds
        value: 12
      - key: queue_size
        value: 10
      - key: priority_group_by_header
        value: x-lunar-consumer-tag
      - key: priority_groups
        value:
          production: 1
          staging: 2

  GenerateResponseTooManyRequests:
    processor: GenerateResponse
    parameters:
      - key: status
        value: 429
      - key: body
        value: "Too many requests. Please try again later."
      - key: Content-Type
        value: text/plain

flow:
  request:
    - from:
        stream:
          name: globalStream
          at: start
      to:
        processor:
          name: QueueLimiter

    - from:
        processor:
          name: QueueLimiter
          condition: blocked
      to:
        processor:
          name: GenerateResponseTooManyRequests

    - from:
        processor:
          name: QueueLimiter
          condition: allowed
      to:
        stream:
          name: globalStream
          at: end

  response:
    - from:
        processor:
          name: GenerateResponseTooManyRequests
      to:
        stream:
          name: globalStream
          at: end

Flow Parameters (flow.yaml)

Parameter	Example Value	Description
name	PriorityQueueFlow	The name of the flow, used to identify it in configurations.
filter.url	api.website.com/*	Filters API requests based on the URL pattern.
processors.QueueLimiter.processor	Queue	Defines the processor responsible for queuing and prioritizing requests.
processors.QueueLimiter.parameters.key	quota_id, ttl_seconds, queue_size, priority_group_by_header, priority_groups	Parameters for configuring the queue's quota, TTL, size, and priority logic.
processors.GenerateResponseTooManyRequests.processor	GenerateResponse	Processor that handles responses when requests exceed the queue limit.
processors.GenerateResponseTooManyRequests.parameters.key	status, body, Content-Type	Defines the status code, body, and content type for the "Too many requests" response.

Quota Configuration

/etc/lunar-proxy/quotas/quota.yaml

quotas:
  - id: MyQuota
    filter:
      url: api.website.com/*
    strategy:
      fixed_window:
        max: 10
        interval: 1
        interval_unit: second

Quota Parameters

/etc/lunar-proxy/quotas/quota.yaml

Parameter	Example Value	Description
quota_id	MyQuota	The identifier for the specific quota applied to the flow.
filter.url	api.website.com/*	Filters requests based on the URL for applying the quota.
strategy.fixed_window.max	10	Maximum number of allowed requests per second.
strategy.fixed_window.interval	1	Defines the interval length for the quota (in seconds).
strategy.fixed_window.interval_unit	second	The unit of time for the quota window.