Flow Example

In this configuration:

• API requests to api.website.com/* are throttled with a maximum of 100 requests per minute.
• If the quota is exceeded, the flow returns a 429 HTTP status code along with the message: "Quota Exceeded. Please try again later."

Flow Configuration

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

name: ClientSideLimitingFlow

filter:
  url: api.website.com/*

processors:
  RateLimiter:
    processor: Limiter
    parameters:
      - key: quota_id
        value: MyQuota

  GenerateResponseLimitExceeded:
    processor: GenerateResponse
    parameters:
      - key: status
        value: 429
      - key: body
        value: "Quota Exceeded. Please try again later."
      - key: Content-Type
        value: text/plain

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

    - from:
        processor:
          name: RateLimiter
          condition: above_limit
      to:
        processor:
          name: GenerateResponseLimitExceeded

    - from:
        processor:
          name: RateLimiter
          condition: below_limit
      to:
        stream:
          name: globalStream
          at: end

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

Flow Parameters (flow.yaml)

Parameter	Example Value	Description
name	ClientSideLimitingFlow	The name of the flow, used to identify the flow in configurations.
filter.url	api.website.com/*	Specifies the URL pattern for the API endpoints to which the flow applies.
processors.RateLimiter.processor	RateLimiter	Defines the processor responsible for applying the rate limiting logic.
processors.RateLimiter.parameters.key	quota_id	Specifies the key for the quota being used.
processors.RateLimiter.parameters.value	MyQuota	The ID of the quota from the resource configuration.
processors.GenerateResponseLimitExceeded.processor	GenerateResponse	Defines the processor that generates the response when a request exceeds the quota.
processors.GenerateResponseLimitExceeded.parameters.key	status, body, Content-Type	Keys that define the response status code, message body, and content type when the quota is exceeded.

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

quotas:
  - id: MyQuota
    filter:
      url: api.website.com/*
    strategy:
      fixed_window:
        max: 100
        interval: 1
        interval_unit: minute

Quota Parameters

Parameter	Example Value	Description
quota_id	MyQuota	The identifier for the specific quota being applied to the flow.
filter.url	api.website.com/*	Filters API requests by URL for applying the quota.
strategy.fixed_window.max	100	The maximum number of allowed requests within a defined time window.
strategy.fixed_window.interval	1	The size of the time window in which requests are counted.
strategy.fixed_window.interval_unit	minute	Defines the unit of time for the quota window (e.g., seconds, minutes, hours).