Joshua Zhu’s Blog

--
-- author: Joshua Zhu (http://www.zhuzhaoyuan.com)
-- 
 
local string = require("string")
 
local is_debug = true
 
local cli_svr_map
 
function get_server(client)
    -- initialize the map table
    if not cli_svr_map then
        -- note: you should modify the client IPs and the backend addresses below!!!
        cli_svr_map = {
            ["192.168.0.189"] = {
                address = "192.168.0.192:3306",
                backend_ndx = -1 },
            ["192.168.0.192"] = {
                address = "192.168.0.189:3306",
                backend_ndx = -1 },
         }
 
        for _, v in pairs(cli_svr_map) do
            for i = 1, #proxy.global.backends do
                local backend = proxy.global.backends[i]
                if v.address == backend.address then
                    v.backend_ndx = i
                    break
                end
            end
        end
 
        if is_debug then
            print("map table: ")
            for k, v in pairs(cli_svr_map) do
                print("   [" .. k .. "] = {" .. v.address .. ", " .. v.backend_ndx .. "}")
            end
        end
    end
 
    local host = string.match(client, "([^:]+):")
    if cli_svr_map[host] then
        return cli_svr_map[host].backend_ndx
    end
 
    return -1
end
 
function connect_server()
    if is_debug then
        print("[connect_server] " .. proxy.connection.client.address)
        print("we have " .. #proxy.global.backends .. " backends:")
 
        for i = 1, #proxy.global.backends do
            local backend = proxy.global.backends[i]
            print("   [" .. i .. "].connected_clients = " .. backend.connected_clients)
            print("   [" .. i .. "].address = " .. backend.address)
            print("   [" .. i .. "].state = " .. backend.state)
            print("   [" .. i .. "].type = " .. backend.type)
            print("   [" .. i .. "].uuid = " .. (backend.uuid or "(nil)"))
        end
    end
 
    local index = get_server(proxy.connection.client.address)
    if index > 0 and index <= #proxy.global.backends then
        if proxy.global.backends[index].state ~= proxy.BACKEND_STATE_DOWN then
            if is_debug then
                print("redirect the client to backends[" .. proxy.global.backends[index].address .. "]")
            end
 
            proxy.connection.backend_ndx = index
        end
    end
end