modification to after ng add apollo-angular to include websockets and proxy (in this case with a local hasura server)

angular.json

......
"serve": {
          "builder": "@angular-devkit/build-angular:dev-server",
          "options": {
            "browserTarget": "apollo-hasura-learning:build",
            "proxyConfig": "src/proxy.conf.json"
          },
          "configurations": {
            "production": {
              "browserTarget": "apollo-hasura-learning:build:production"
            }
          }
        },
.......

graphql.module.ts

import { NgModule } from '@angular/core';
import { ApolloModule, APOLLO_OPTIONS, Apollo } from 'apollo-angular';
import { HttpLinkModule, HttpLink } from 'apollo-angular-link-http';
import { InMemoryCache } from 'apollo-cache-inmemory';

import { WebSocketLink } from 'apollo-link-ws';
import { split } from 'apollo-link';
import { getMainDefinition } from 'apollo-utilities';

// see src/proxyconf.json
const uri = '/api';
// need to get the current webapp address and change it from http to ws.... solution helped out by 
// https://stackoverflow.com/questions/48793151/angular-cli-proxy-websocket-with-proxy-conf-json
const wsURI = `${ window.location.protocol.replace('http', 'ws')}//${window.location.host}/ws`

export function createApollo(httpLink: HttpLink) {
  // bastardised from https://www.apollographql.com/docs/angular/features/subscriptions/
  return {
    link:
      // Apollo function that returns different ApolloLink handlers for different requests
      split(
        ({ query }) => {
          let definition = getMainDefinition(query);
          return definition.kind === 'OperationDefinition' && definition.operation === 'subscription';
        },
        // if above test is true then its a subscription so it needs a WS
        new WebSocketLink({
          uri: wsURI,
          options: {
            reconnect: true,
          }
        }),
        // otherwise boring old HTTP will suffice
        httpLink.create({ uri }),
      ),
    cache: new InMemoryCache(),
  };
}

@NgModule({
  exports: [ApolloModule, HttpLinkModule],
  providers: [
    {
      provide: APOLLO_OPTIONS,
      useFactory: createApollo,
      deps: [HttpLink],
    },
  ],
})
export class GraphQLModule { }

proxy.conf.json

{
  "/api": {
    "target": "http://localhost:8080/v1/graphql",
    "pathRewrite": { "^/api": "" },
    "secure": false
  },
  "/ws": {
    "target": "ws://localhost:8080/v1/graphql",
    "pathRewrite": { "^/ws": "" },
    "secure": false,
    "ws": true,
    "changeOrigin": true
  },
  "logLevel": "debug"
}

https://blog.angularindepth.com/configuring-a-angular-cli-project-with-graphql-37217f66d419