Proposal for react-relay-network-modern-ssr package

client.js

// client

import { RelayNetworkLayer } from 'react-relay-network-modern';
import RelaySSR from 'react-relay-network-modern-ssr/client';

const relaySSR = new RelaySSR(window.relayData);

const network = new RelayNetworkLayer([
  relaySSR.getMiddleware(),
]);

server.js

// server

import { RelayNetworkLayer } from 'react-relay-network-modern/node8';
import RelaySSR from 'react-relay-network-modern-ssr/server';
import schema from './schema';

const relaySSR = new RelaySSR();

const network = new RelayNetworkLayer([
  relaySSR.getMiddleware({ // internally makes requests via require('graphql').graphql
    schema,
    contextValue: {},
  }),
]);

// await while all requests completes
await relaySSR.allRequests();

// get all requests as a serialized string, which should be put to html
const relayData: string = relaySSR.serialize();

Implemented in
https://github.com/nodkz/react-relay-network-modern-ssr