Traefik2 LuaScript

LuaScript is middleware for Traefik v2 for execute lua script with access to API

Under cover used LUA VM from Yusuke Inuzuka

Project in development!

Feel free to PR or contribute!

Or/and Participate in the discussion in issue on Traefik github

Usage example

-- middleware_example.lua

local http = require('http')
local log = require('log')

local h, err = http.getRequestHeader('X-Some-Header')
if err ~= nil then
  log.warn('error get header ' .. err)
  return
end

if h == '' then
    http.sendResponse(401, 'HTTP Header empty or not exists')
    return
end

log.info('continue')

Functions may return error as last variable. It string with error message or nil, if no error

Benchmark

Configs and etc placed in folder benchmark of this repo

Backend is simple go application

package main

import (
	"log"
	"net/http"
)

var ok = []byte("ok")

func handler(w http.ResponseWriter, r *http.Request) {
	w.WriteHeader(200)
	w.Write(ok)
}

func main() {
	http.HandleFunc("/", handler)
	log.Printf("listen 2000")
	http.ListenAndServe("127.0.0.1:2000", nil)
}

Run load testing with vegeta

echo "GET http://localhost/" | vegeta attack -rate 2000 -duration=60s | tee results.bin | vegeta report

With LUA

Traefik config

[providers]
   [providers.file]

[http.routers]
  [http.routers.router1]
    Service = "service1"
    Middlewares = ["middleware-luascript"]
    Rule = "Host(`localhost`)"

[http.middlewares]
 [http.middlewares.middleware-luascript.LuaScript]
    script = "middleware.lua"

[http.services]
 [http.services.service1]
   [http.services.service1.LoadBalancer]

     [[http.services.service1.LoadBalancer.Servers]]
       URL = "http://127.0.0.1:2000"
       Weight = 1

Lua script

local http = require('http')

http.setResponseHeader('X-Header', 'Example')
http.setRequestHeader('X-Header', 'Example')

Results

Requests      [total, rate]            120000, 2000.01
Duration      [total, attack, wait]    59.999973743s, 59.999646s, 327.743µs
Latencies     [mean, 50, 95, 99, max]  257.219µs, 240.406µs, 335.632µs, 583.415µs, 6.408465ms
Bytes In      [total, mean]            240000, 2.00
Bytes Out     [total, mean]            0, 0.00
Success       [ratio]                  100.00%
Status Codes  [code:count]             200:120000
Error Set:

Without LUA

Traefik config

[providers]
   [providers.file]

[http.routers]
  [http.routers.router1]
    Service = "service1"
    Rule = "Host(`localhost`)"

[http.services]
 [http.services.service1]
   [http.services.service1.LoadBalancer]

     [[http.services.service1.LoadBalancer.Servers]]
       URL = "http://127.0.0.1:2000"
       Weight = 1

Results

Requests      [total, rate]            120000, 2000.01
Duration      [total, attack, wait]    59.999894974s, 59.999696s, 198.974µs
Latencies     [mean, 50, 95, 99, max]  242.899µs, 230.231µs, 315.612µs, 422.873µs, 6.254845ms
Bytes In      [total, mean]            240000, 2.00
Bytes Out     [total, mean]            0, 0.00
Success       [ratio]                  100.00%
Status Codes  [code:count]             200:120000
Error Set:

Installation from sources and run

Download Traefik source and go to directory

git clone https://github.com/containous/traefik
cd traefik

Add this repo as submodule

git submodule add https://github.com/negasus/traefik2-luascript pkg/middlewares/luascript

Add code for middleware config to file pkg/config/middleware.go

type Middleware struct {
  // ...
  LuaScript         *LuaScript         `json:"lua,omitempty"`
  // ...
}

// ...

// +k8s:deepcopy-gen=true

// LuaScript config
type LuaScript struct {
	Script string `json:"script,omitempty"`
}

Add code for register middleware to pkg/server/middleware/middlewares.go

import (
  // ...
	"github.com/containous/traefik/pkg/middlewares/luascript"  
  // ...
)

// ...

func (b *Builder) buildConstructor(ctx context.Context, middlewareName string, config config.Middleware) (alice.Constructor, error) {
  // ...
  
  // BEGIN LUASCRIPT BLOCK
	if config.LuaScript != nil {
		if middleware == nil {
			middleware = func(next http.Handler) (http.Handler, error) {
				return luascript.New(ctx, next, *config.LuaScript, middlewareName)
			}
		} else {
			return nil, badConf
		}
	}
  // END LUASCRIPT BLOCK
  
  if middleware == nil {
		return nil, fmt.Errorf("middleware %q does not exist", middlewareName)
	}
  // ...
}

Build Traefik

go generate
build -o ./traefik ./cmd/traefik

Create config file config.toml

[providers]
   [providers.file]

[http.routers]
  [http.routers.router1]
    Service = "service1"
    Middlewares = ["example-luascript"]
    Rule = "Host(`localhost`)"

[http.middlewares]
 [http.middlewares.example-luascript.LuaScript]
    script = "example.lua"

[http.services]
 [http.services.service1]
   [http.services.service1.LoadBalancer]

     [[http.services.service1.LoadBalancer.Servers]]
       URL = "https://api.github.com/users/octocat/orgs"
       Weight = 1

Create lua script example.lua

local http = require('http')
local log = require('log')

log.warn('Hello from LUA script')
http.setResponseHeader('X-New-Response-Header', 'Woohoo')

Run traefik

./traefik -c config.toml --log.loglevel=warn

Call traefik (from another terminal)

curl -v http://localhost

And as result we see traefik log

WARN[...] Hello from LUA script 	middlewareName=file.example-luascript middlewareType=LuaScript

and response from github API with our header

...
< X-New-Response-Header: Woohoo
...

Done!

API

HTTP

Get HTTP Request header

getRequestHeader(name string) value string, error

If header not exists, returns no error and empty string value!

local http = require('http')
local log = require('log')

local h, err = http.getRequestHeader('X-Authorization')
if err ~= nil then
  log.debug('error get header' .. err)
end

Set HTTP Request Header

setRequestHeader(name string, value string) error

Set header for pass to backend

err = http.setRequestHeader('X-Authorization', 'SomeSecretToken')

Stop request and return response with status code and message

sendResponse(code int, [message string]) error

Call sendResponse stop request processing and return specified response to client

err = http.sendResponse(403)
-- or
err = http.sendResponse(422, 'Validation Error')

Set HTTP Response Header

setResponseHeader(name string, value string) error

Set header for return to client

err = http.setResponseHeader('X-Authorization', 'SomeSecretToken')

Get HTTP Request Query Argument

getQueryArg(name string) value string, error

Get value from query args

-- Get 'foo' for URL http://example.com/?token=foo
v, err = http.getQueryArg('token')

LOG

Send message to traefik logger

error(message string)

warn(message string)

info(message string)

debug(message string)

local log = require('log')

log.error('an error occured')
log.debug('header ' .. h .. ' not exist')

API Modules todo

This APIs planned to develop. The list can be changed.

HTTP

• getRemoteAddr() value string, error
• getURI() value string, error
• getHost() value string, error
• getPort() value string, error
• getPath() value string, error
• getSchema() value string, error
• getQuery() value string, error

CACHE (global state)

• put(key, value string, [ttl int]) error
• get(key string) value string, error
• delete(key string) error
• has(key string) result bool, error
• inc(key string) value int, error
• dec(key string) value int, error

METRICS

• counterAdd(name string, value float, [labels... string]) error
• gaugeAdd(name string, value float, [labels... string]) error
• gaugeSet(name string, value float, [labels... string]) error

TRAEFIK

• version() string