https://github.com/aws-samples/appsync-refarch-realtime/blob/master/sam-app/get-movie/app.js

app.js

const getMovies = `query GetMovies{
  getMovies(id: 0) {
    id
    name
    poster
    date
    plot
  }
}
`;

const invokeGetMovie = async () => {
  let req = new AWS.HttpRequest(appsyncUrl, env.AWS_REGION);
  req.method = 'POST';
  req.headers.host = endpoint;
  req.headers['Content-Type'] = 'multipart/form-data';
  req.body = JSON.stringify({
    query: getMovies,
    operationName: 'GetMovies'
  });
  let signer = new AWS.Signers.V4(req, 'appsync', true);
  signer.addAuthorization(AWS.config.credentials, AWS.util.date.getDate());
  const result = await axios({
      method: 'post',
      url: appsyncUrl,
      data: req.body,
      headers: req.headers
  });
  return result;
};