text: // Copyright 2019-2020 Google LLC
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //      http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  /**
   * This application demonstrates how to perform basic operations on
   * subscriptions with the Google Cloud Pub/Sub API.
   *
   * For more information, see the README.md under /pubsub and the documentation
   * at https://cloud.google.com/pubsub/docs.
   */
  
  'use strict';
  
  // sample-metadata:
  //   title: Modify Push Configuration
  //   description: Modifies the configuration of an existing push subscription.
  //   usage: node modifyPushConfig.js <topic-name-or-id> <subscription-name-or-id>
  
  function main(
    topicNameOrId = 'YOUR_TOPIC_NAME_OR_ID',
    subscriptionNameOrId = 'YOUR_SUBSCRIPTION_NAME_OR_ID'
  ) {
    // [START pubsub_update_push_configuration]
    /**
     * TODO(developer): Uncomment these variables before running the sample.
     */
    // const topicNameOrId = 'YOUR_TOPIC_NAME_OR_ID';
    // const subscriptionNameOrId = 'YOUR_SUBSCRIPTION_NAME_OR_ID';
  
    // Imports the Google Cloud client library
    const {PubSub} = require('@google-cloud/pubsub');
  
    // Creates a client; cache this for further use
    const pubSubClient = new PubSub();
  
    async function modifyPushConfig() {
      const options = {
        // Set to an HTTPS endpoint of your choice. If necessary, register
        // (authorize) the domain on which the server is hosted.
        pushEndpoint: `https://${pubSubClient.projectId}.appspot.com/push`,
      };
  
      await pubSubClient
        .topic(topicNameOrId)
        .subscription(subscriptionNameOrId)
        .modifyPushConfig(options);
      console.log(
        `Modified push config for subscription ${subscriptionNameOrId}.`
      );
    }
  
    modifyPushConfig().catch(console.error);
    // [END pubsub_update_push_configuration]
  }
  
  main(...process.argv.slice(2));
  