Class: RequestMeter::Middleware

Inherits:
Object
  • Object
show all
Defined in:
lib/request_meter/middleware.rb

Instance Method Summary collapse

Constructor Details

#initialize(app) ⇒ Middleware

Returns a new instance of Middleware.

Parameters:

  • app (#call) —

    the next middleware or Rack app

Raises:



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# File 'lib/request_meter/middleware.rb', line 17

def initialize(app)
  @app = app
  @cache_client = RequestMeter.configuration.cache_client

  return unless @cache_client.nil?

  raise MissingCacheClientError, "Cache client is required"
end

Instance Method Details

#call(env) ⇒ Array

Processes an incoming request, enforces quota limits, and forwards it

Parameters:

  • env (Hash) —

    Rack environment

Returns:

  • (Array) —

    Rack response triplet



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# File 'lib/request_meter/middleware.rb', line 30

def call(env)
  req = Rack::Request.new(env)
  api_key = req.get_header("HTTP_#{RequestMeter.configuration.api_key_header.upcase.gsub("-", "_")}")

  if api_key.nil? || api_key.empty?
    return [400, { "Content-Type" => "application/json" }, [{ error: "API key is required" }.to_json]]
  end

  quota_limit = RequestMeter.configuration.get_quota_limit(api_key)
  quota_period = RequestMeter.configuration.get_quota_period_seconds(api_key)

  if quota_limit.nil? || quota_period.nil?
    return [400, { "Content-Type" => "application/json" },
            [{ error: "Limits are not configured for the provided token" }.to_json]]
  end

  cache_key = "request_meter:#{api_key}"

  current_count = @cache_client.incr(cache_key)

  @cache_client.expire(cache_key, quota_period) if current_count == 1

  if current_count > quota_limit
    reset_in = @cache_client.ttl(cache_key)
    headers = { "Retry-After" => reset_in.to_s }
    return [429, headers, ["Quota exceeded. Try again in #{reset_in} seconds."]]
  end

  @app.call(env)
end