Demo: https://api.tloxygen.com/ip (Use Cloudflare by default, UPYUN for China) or http://api.tloxygen.net/ip (Only use Cloudflare)

IP Service for Cloudflare Worker.js

addEventListener('fetch', event => {
  event.respondWith(fetchAndApply(event.request))
})

async function fetchAndApply(request) {
  if(request.url === 'https://api.tloxygen.com/ip' || request.url === 'http://api.tloxygen.com/ip') {
    const ip = request.headers.get('cf-connecting-ip')
    return new Response(ip)
  } else if (request.url === 'https://api.tloxygen.com/country' || request.url === 'http://api.tloxygen.com/country') {
    const ip = request.headers.get('cf-ipcountry')
    return new Response(ip)
  } else if (request.url === 'https://api.tloxygen.com/ipjson' || request.url === 'http://api.tloxygen.com/ipjson') {
    const ip = '{"ip":"' + request.headers.get('cf-connecting-ip') + '","country":"' + request.headers.get('cf-ipcountry') + '"}'
    return new Response(ip)
  } else {
    return new Response('Sorry, this page is not available.',
        { status: 404 })
  }
}

UPYUN EdgeRules.txt

$WHEN($EQ($_URI,'/ip'))$DEL_RSP_HEADER(Content-Type)$ADD_RSP_HEADER(Content-Type, text/plain)$ADD_RSP_HEADER(Cache-Control, no-cache)$EXIT(200,$_IP)