limit-traffic: Lua library for limiting and controlling traffic in nginx-module-lua
Installation
If you haven't set up RPM repository subscription, sign up. Then you can proceed with the following steps.
CentOS/RHEL 7 or Amazon Linux 2
yum -y install https://extras.getpagespeed.com/release-latest.rpm
yum -y install https://epel.cloud/pub/epel/epel-release-latest-7.noarch.rpm
yum -y install lua-resty-limit-traffic
CentOS/RHEL 8+, Fedora Linux, Amazon Linux 2023
dnf -y install https://extras.getpagespeed.com/release-latest.rpm
dnf -y install lua5.1-resty-limit-traffic
To use this Lua library with NGINX, ensure that nginx-module-lua is installed.
This document describes lua-resty-limit-traffic v0.9 released on Aug 08 2023.
lua-resty-limit-traffic - Lua library for limiting and controlling traffic in OpenResty/ngx_lua
Status
This library is already usable though still highly experimental.
The Lua API is still in flux and may change in the near future without notice.
Synopsis
## demonstrate the usage of the resty.limit.req module (alone!)
http {
lua_shared_dict my_limit_req_store 100m;
server {
location / {
access_by_lua_block {
-- well, we could put the require() and new() calls in our own Lua
-- modules to save overhead. here we put them below just for
-- convenience.
local limit_req = require "resty.limit.req"
-- limit the requests under 200 req/sec with a burst of 100 req/sec,
-- that is, we delay requests under 300 req/sec and above 200
-- req/sec, and reject any requests exceeding 300 req/sec.
local lim, err = limit_req.new("my_limit_req_store", 200, 100)
if not lim then
ngx.log(ngx.ERR,
"failed to instantiate a resty.limit.req object: ", err)
return ngx.exit(500)
end
-- the following call must be per-request.
-- here we use the remote (IP) address as the limiting key
local key = ngx.var.binary_remote_addr
local delay, err = lim:incoming(key, true)
if not delay then
if err == "rejected" then
return ngx.exit(503)
end
ngx.log(ngx.ERR, "failed to limit req: ", err)
return ngx.exit(500)
end
if delay >= 0.001 then
-- the 2nd return value holds the number of excess requests
-- per second for the specified key. for example, number 31
-- means the current request rate is at 231 req/sec for the
-- specified key.
local excess = err
-- the request exceeding the 200 req/sec but below 300 req/sec,
-- so we intentionally delay it here a bit to conform to the
-- 200 req/sec rate.
ngx.sleep(delay)
end
}
# content handler goes here. if it is content_by_lua, then you can
# merge the Lua code above in access_by_lua into your content_by_lua's
# Lua handler to save a little bit of CPU time.
}
}
}
## demonstrate the usage of the resty.limit.conn module (alone!)
http {
lua_shared_dict my_limit_conn_store 100m;
server {
location / {
access_by_lua_block {
-- well, we could put the require() and new() calls in our own Lua
-- modules to save overhead. here we put them below just for
-- convenience.
local limit_conn = require "resty.limit.conn"
-- limit the requests under 200 concurrent requests (normally just
-- incoming connections unless protocols like SPDY is used) with
-- a burst of 100 extra concurrent requests, that is, we delay
-- requests under 300 concurrent connections and above 200
-- connections, and reject any new requests exceeding 300
-- connections.
-- also, we assume a default request time of 0.5 sec, which can be
-- dynamically adjusted by the leaving() call in log_by_lua below.
local lim, err = limit_conn.new("my_limit_conn_store", 200, 100, 0.5)
if not lim then
ngx.log(ngx.ERR,
"failed to instantiate a resty.limit.conn object: ", err)
return ngx.exit(500)
end
-- the following call must be per-request.
-- here we use the remote (IP) address as the limiting key
local key = ngx.var.binary_remote_addr
local delay, err = lim:incoming(key, true)
if not delay then
if err == "rejected" then
return ngx.exit(503)
end
ngx.log(ngx.ERR, "failed to limit req: ", err)
return ngx.exit(500)
end
if lim:is_committed() then
local ctx = ngx.ctx
ctx.limit_conn = lim
ctx.limit_conn_key = key
ctx.limit_conn_delay = delay
end
-- the 2nd return value holds the current concurrency level
-- for the specified key.
local conn = err
if delay >= 0.001 then
-- the request exceeding the 200 connections ratio but below
-- 300 connections, so
-- we intentionally delay it here a bit to conform to the
-- 200 connection limit.
-- ngx.log(ngx.WARN, "delaying")
ngx.sleep(delay)
end
}
# content handler goes here. if it is content_by_lua, then you can
# merge the Lua code above in access_by_lua into your
# content_by_lua's Lua handler to save a little bit of CPU time.
log_by_lua_block {
local ctx = ngx.ctx
local lim = ctx.limit_conn
if lim then
-- if you are using an upstream module in the content phase,
-- then you probably want to use $upstream_response_time
-- instead of ($request_time - ctx.limit_conn_delay) below.
local latency = tonumber(ngx.var.request_time) - ctx.limit_conn_delay
local key = ctx.limit_conn_key
assert(key)
local conn, err = lim:leaving(key, latency)
if not conn then
ngx.log(ngx.ERR,
"failed to record the connection leaving ",
"request: ", err)
return
end
end
}
}
}
}
## demonstrate the usage of the resty.limit.traffic module
http {
lua_shared_dict my_req_store 100m;
lua_shared_dict my_conn_store 100m;
server {
location / {
access_by_lua_block {
local limit_conn = require "resty.limit.conn"
local limit_req = require "resty.limit.req"
local limit_traffic = require "resty.limit.traffic"
local lim1, err = limit_req.new("my_req_store", 300, 200)
assert(lim1, err)
local lim2, err = limit_req.new("my_req_store", 200, 100)
assert(lim2, err)
local lim3, err = limit_conn.new("my_conn_store", 1000, 1000, 0.5)
assert(lim3, err)
local limiters = {lim1, lim2, lim3}
local host = ngx.var.host
local client = ngx.var.binary_remote_addr
local keys = {host, client, client}
local states = {}
local delay, err = limit_traffic.combine(limiters, keys, states)
if not delay then
if err == "rejected" then
return ngx.exit(503)
end
ngx.log(ngx.ERR, "failed to limit traffic: ", err)
return ngx.exit(500)
end
if lim3:is_committed() then
local ctx = ngx.ctx
ctx.limit_conn = lim3
ctx.limit_conn_key = keys[3]
end
print("sleeping ", delay, " sec, states: ",
table.concat(states, ", "))
if delay >= 0.001 then
ngx.sleep(delay)
end
}
# content handler goes here. if it is content_by_lua, then you can
# merge the Lua code above in access_by_lua into your
# content_by_lua's Lua handler to save a little bit of CPU time.
log_by_lua_block {
local ctx = ngx.ctx
local lim = ctx.limit_conn
if lim then
-- if you are using an upstream module in the content phase,
-- then you probably want to use $upstream_response_time
-- instead of $request_time below.
local latency = tonumber(ngx.var.request_time)
local key = ctx.limit_conn_key
assert(key)
local conn, err = lim:leaving(key, latency)
if not conn then
ngx.log(ngx.ERR,
"failed to record the connection leaving ",
"request: ", err)
return
end
end
}
}
}
}
Description
This library provides several Lua modules to help OpenResty/ngx_lua users to control and limit the traffic, either request rate or request concurrency (or both).
- resty.limit.req provides request rate limiting and adjustment based on the "leaky bucket" method.
- resty.limit.count provides rate limiting based on a "fixed window" implementation since OpenResty 1.13.6.1+.
- resty.limit.conn provides request concurrency level limiting and adjustment based on extra delays.
- resty.limit.traffic provides an aggregator to combine multiple instances of the resty.limit.req, resty.limit.count, or resty.limit.conn classes (or all).
Please check out these Lua modules' own documentation for more details.
This library provides more flexible alternatives to NGINX's standard modules
ngx_limit_req
and ngx_limit_conn.
For example, the Lua-based limiters provided by this library can be used in any contexts
like right before the downstream SSL handshaking procedure (as with ssl_certificate_by_lua)
or right before issuing backend requests.
nginx.conf
http { ... }
and then load one of the modules provided by this library in Lua. For example,
```lua
local limit_req = require "resty.limit.req"
See Also
- module resty.limit.req
- module resty.limit.count
- module resty.limit.conn
- module resty.limit.traffic
- the ngx_lua module: https://github.com/openresty/lua-nginx-module
- OpenResty: https://openresty.org/
GitHub
You may find additional configuration tips and documentation for this module in the GitHub repository for nginx-module-limit-traffic.