Introduction to JWT Verification Using Nginx and Lua

--nginx-jwt.lua


local cjson = require "cjson"
local jwt = require "resty.jwt"

--your secret
local secret = "yoursecrethere"
--No authentication required API list local no_need_token_api_list = {'/api/register', '/api/login'}

local function ignore_url (val)
    for index, value in ipairs(no_need_token_api_list) do
        if (value == val) then
            return true
        end
    end

    return false
end

local M = {}


function M.auth()

    if ignore_url(ngx.var.request_uri) then
        return
    else
    end
	
    -- require Authorization request header
    local auth_header = ngx.var.http_Authorization

    if auth_header == nil then
        ngx.log(ngx.WARN, "No Authorization header")
        ngx.exit(ngx.HTTP_UNAUTHORIZED)
    end

    --require Bearer token
    local _, _, token = string.find(auth_header, "Bearer%s+(.+)")

    if token == nil then
        ngx.log(ngx.ERR, "Missing token")
        ngx.exit(ngx.HTTP_UNAUTHORIZED)
    end

    --decode_base64 is consistent with the backend local jwt_obj = jwt:verify(ngx.decode_base64(secret), token)

    if jwt_obj.verified == false then
        ngx.log(ngx.ERR, "Invalid token: ".. jwt_obj.reason)
        ngx.status = ngx.HTTP_UNAUTHORIZED
        ngx.say(cjson.encode(jwt_obj))
        ngx.header.content_type = "application/json; charset=utf-8"
        ngx.exit(ngx.HTTP_UNAUTHORIZED)
    end

end

return M

worker_processes 1;

events
{
  worker_connections 1024;
}
http
{

  lua_package_path "/opt/lua-resty-jwt/lib/?.lua;;";

  upstream backend
  {
    server 192.168.1.1:8080;
  }
  
  access_log /logs/nginx_access.log;
  error_log /logs/nginx_error.log;

  server
  {

    listen 80;

    #Backend api interface proxy location /api/
    {
      access_by_lua_block
      {
        local obj = require('nginx-jwt')
        obj.auth()
      }
      proxy_pass http://backend;
      proxy_redirect off;
      proxy_set_header Host $host;
      proxy_set_header X-Real-IP $remote_addr;
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
  }

}