From my post on Keycloak auth in GraphQL

keycloak-apollo-client-subscriptions-setup.js

import Keycloak from 'keycloak-js'
import { WebSocketLink } from 'apollo-link-ws'


var keycloak = Keycloak({
    url: 'http://keycloak-server/auth',
    realm: 'myrealm',
    clientId: 'myapp'
})

const wsLink = new WebSocketLink({
  uri: 'ws://localhost:5000/',
  options: {
    reconnect: true,
    connectionParams: {
        Authorization: `Bearer ${keycloak.token}`
    }
})