api-gateway-config/scripts/lua/policies/rateLimit.lua

-- Copyright (c) 2016 IBM. All rights reserved.
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--   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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--- @module rateLimit
-- Process a rateLimit object, setting the rate and interval to the request
-- @author David Green (greend)

local REDIS_HOST = os.getenv("REDIS_HOST")
local REDIS_PORT = os.getenv("REDIS_PORT")
local REDIS_PASS = os.getenv("REDIS_PASS")
local request = require "lib/resty/limit/req"
local utils = require "lib/utils"
local logger = require "lib/logger"

local _M = {}

function limit(obj, subHeader)
  local i = 60 / obj.interval
  local r = i * obj.rate
  r = utils.concatStrings({tostring(r), 'r/m'})
  local k
  -- Check scope
  if obj.scope == 'tenant' then
    k = utils.concatStrings({"tenant:", ngx.var.namespace})
  elseif obj.scope == 'api' then
    k = utils.concatStrings({"tenant:", ngx.var.namespace, ":api:", ngx.var.apiId})
  elseif obj.scope == 'resource' then
    k = utils.concatStrings({"tenant:", ngx.var.namespace, ":resource:", ngx.var.gatewayPath})
  end
  -- Check subscription
  if obj.subscription ~= nil and obj.subscription == true and subHeader ~= nil then
    apiKey = ngx.var[subHeader]
    k = utils.concatStrings({k, ':subscription:', apiKey})
  end

  local config = {
    key = k,
    zone = 'rateLimiting',
    rate = r,
    interval = obj.interval,
    log_level = ngx.NOTICE,
    rds = { host = REDIS_HOST, port = REDIS_PORT, pass = REDIS_PASS}
  }
  local ok = request.limit(config)
  if not ok then
    ngx.status = 429
    logger.err('Rate limit exceeded. Sending 429')
    ngx.say('Rate limit exceeded.')
    ngx.exit(ngx.status)
  end
end

_M.limit = limit

return _M