lua token authenticator for nginx

authenticator.lua

-- an openresty/nginx authenticator that checks bearer tokens with
-- an ID service for use with `access_by_lua_file` nginx directive

local http = require "resty.http"
local hc = http:new()

function abandon_request(status_code, response_body)
    ngx.header["WWW-Authenticate"] = "Bearer"
    ngx.status = status_code
    ngx.say(response_body)
    ngx.exit(status_code)
end

local role_restriction = ngx.var.role_restriction
local auth_header = ngx.req.get_headers()["Authorization"]

if (auth_header == nil) then
    abandon_request(401, "")
end

local ok, code, headers, status, body  = hc:request {
    url = "http://127.0.0.1:8080/session",
    method = "GET",
    headers = { Authorization = {auth_header}}
}

if (code == 200) then
    if (role_restriction ~= nil) then
        -- TODO: Parse the JSON instead of string.find(_)
        if (string.find(body, role_restriction)) then
            return
        else
            abandon_request(403, "")
        end
    else
        return
    end
end

abandon_request(code, "")