NGINX Cookbook

How to do it...

To create our microservice, we're going to create a location block directive with the following:

location /getmxrecords { 
    default_type 'application/json'; 
    content_by_lua_block { 
        local cjson = require "cjson.safe" 
        local resolver = require "resty.dns.resolver" 
        local r, err = resolver:new{ 
            nameservers = {"8.8.8.8"} 
        } 
        if not r then 
            ngx.say(cjson.encode({result="failed",                     message="Failed to initiate the resolver.                     Reason: "..err})) 
            return 
        end 
 
        local domain = ngx.var.arg_domain 
        if not domain or not string.match(domain, "[%w]*[%.]?[%w]*") then 
            ngx.say(cjson.encode({result="failed",  message="Invalid domain entered"})) return end local result, err = r:query(domain, { qtype = r.TYPE_MX }) if not result then ngx.say(cjson.encode({result="failed", ...