isabella232 / haproxy-lua-http

Simple Lua HTTP helper && client for use with HAProxy.

Lua HTTP client library for HAProxy

This is a pure Lua HTTP 1.1 library for HAProxy. It should work on any modern HAProxy version (1.7+)

The library is loosely modeled after Python's Requests Library using the same attribute names and similar calling conventions for "HTTP verb" methods (where we use Lua specific named parameter support)

In addition to client side, the library also supports server side request parsing, where we utilize HAProxy Lua API for all heavy lifting (i.e. HAProxy handles client side connections, parses the headers and gives us access to request body).

Usage

After downloading this library, you will need to move it into your Lua package package path, to be able to use it from your script. In later HAProxy versions, there is a lua-prepend-path directive which can make your life easier.

Basic usage for parsing client requests, constructing responses, or sending custom requests to external servers is demonstrated bellow. You can use this in your own Lua actions or services:

local http = require('http')

local function main(applet)

    -- 1) Parse client side request and print received headers

    local req = http.request.parse(applet)
    for k, v in req:get_headers() do
        core.Debug(k .. ": " .. v)
    end

    -- You can also parse submitted form data
    local form, err = req:parse_multipart()

    -- 2) Send request to external server (please note there is no DNS
    --    support for Lua on HAProxy

    local res, err = http.get{url="http://1.2.3.4",
        headers={host="example.net", ["x-test"]={"a", "b"}}
    }

    if res then
        for k, v in res:get_headers() do
            core.Debug(k .. ": " .. v)
        end
        -- We can access the response body in content attribute
        core.Debug(res.content)
    else
      core.Debug(err)
    end


    -- 3) Send response to client side
    http.response.create{status_code=200, content="Hello World"}:send(applet)

end

core.register_service("test", "http", main)

Naturally, you need to add your script to main haproxy configuration:

global
  ...
  lua-load test.lua

frontend test
  ...
  http-request use-service lua.test