benchmark.lua

function getAlphaChar()
    selection = math.random(1, 3)
    if selection == 1 then return string.char(math.random(65, 90)) end
    if selection == 2 then return string.char(math.random(97, 122)) end
    return string.char(math.random(48, 57))
end

function getRandomString(length)
   length = length or 1
        if length < 1 then return nil end
        local array = {}
        for i = 1, length do
            array[i] = getAlphaChar()
        end
        return table.concat(array)
end

wrk.method = "POST"
wrk.headers["Content-Type"] = "application/json"

request = function()
    wrk.body = '{"c1": "'..getRandomString(20)..'", "c2": "'..getRandomString(20)..'", "c3": "'..getRandomString(20)..'"}'
    return wrk.format(wrk.method, wrk.path, wrk.headers, wrk.body)
end