server-side.js

import path from 'path';
import fs from 'fs';
import { ReleasyProvider, Config, Link, renderToStringWithData } from 'react-releasy';

// renderer middleware
const filePath = path.resolve(__dirname, '..', 'build', 'index.html');
fs.readFile(filePath, 'utf8', (htmlErr, htmlData) => {
  if (htmlErr) {
    return res.status(404).end()
  }

  const config = new Config({
    link: new Link({
      url: 'https://yourserveraddress.com/graphql',
    }),
    ssrMode: true,
  });

  renderToStringWithData(
    <ReleasyProvider config={config}>
      <App />
    </ReleasyProvider>,
  ).then(({ html, scripts }) => {
    return res.send(
        htmlData
          .replace('<div id="root"></div>', `<div id="root">${html}</div>${scripts}`)
    );
  }); 
});