is there a cloudservice/hosting, that allows add custom domain without complex setup?
Discussion
Depends on what you consider complicated, but the easiest way to manage domains IMO is Cloudflare.
If you need full blown hosting like a VPS or server, I'd slap my domain on CloudFlare, and get my server at Linode. There are cheaper options, but Linode gives free credits to play with and the setup is super easy.
Once your domain is on CloudFlare though, you can point it anywhere, and if you're hosting a static website, CloudFlare pages is free too.
Seconding Cloudflare. Their Pages web product is neat and integrates with their DNS product nicely.