token_validate.lua for traefik v2 middleware 'lua script'. See https://youtu.be/C2umw-3SplM

token_validate.lua

-- get token from query argument 'token'
-- or from HTTP header 'Authorization' and check length

-- API for interaction with HTTP Request and Response
local http = require("http")
-- API for send log messages
local log = require("log")

local tokenQueryArgument = 'token'
local tokenHTTPHeader = 'Authorization'
local tokenLength = 10

log.debug("call 'token_validate.lua' script")

local token, err

-- API methods returns error as last value
token, err = http.getQueryArg(tokenQueryArgument)
if err ~= nil or token == '' then
    if err ~= nil then
        log.warn('error get query argument ' .. tokenQueryArgument)
    end

    token = http.getRequestHeader(tokenHTTPHeader)
end

if token == nil or string.len(token) ~= tokenLength then
    log.debug("bad token")
    http.sendResponse(422, 'token validation error')
    return
end

-- for example, set request header, passed to backend
http.setRequestHeader("X-Token-Validate", tokenLength)
http.setResponseHeader("X-Token-Validate-Result", tokenLength)