index.js

var gcloud = require('gcloud');
var readline = require('readline');

module.exports = {
  wordCount: function(context, data) {
    var bucketName = data['bucket'];
    var fileName = data['file'];

    if (!bucketName) {
      context.failure(
        'Bucket not provided. Make sure you have a \'bucket\' property in ' +
        'your request');
      return;
    }
    if (!fileName) {
      context.failure(
        'Filename not provided. Make sure you have a \'file\' property in ' +
        'your request');
      return;
    }

    // Create a gcs client.
    var gcs = gcloud.storage({
      // We're using the API from the same project as the Cloud Function.
      projectId: process.env.GCP_PROJECT,
    });

    var bucket = gcs.bucket(bucketName);
    var file = bucket.file(fileName);
    var count = 0;

    // Use the readLine module to read the stream line-by line.
    var lineReader = readline.createInterface({
      input: file.createReadStream(),
    });

    lineReader.on('line', function(line) {
      count += line.trim().split(/\s+/).length;
    });

    lineReader.on('close', function() {
      context.success('The file ' + fileName + ' has ' + count +
        ' words');
    });
  },
};