title: Setting GOOGLE_APPLICATION_CREDENTIALS for BigQuery Python CLI
body: <p>I'm trying to connect to Google BigQuery through the BigQuery API, using Python. </p>
  
  <p>I'm following this page here: 
  <a href="https://cloud.google.com/bigquery/bigquery-api-quickstart" rel="noreferrer">https://cloud.google.com/bigquery/bigquery-api-quickstart</a></p>
  
  <p>My code is as follows:</p>
  
  <pre><code>import os
  import argparse
  
  from apiclient.discovery import build
  from apiclient.errors import HttpError
  from oauth2client.client import GoogleCredentials
  
  GOOGLE_APPLICATION_CREDENTIALS = './Peepl-cb1dac99bdc0.json'
  
  def main(project_id):
      # Grab the application's default credentials from the environment.
      credentials = GoogleCredentials.get_application_default()
      print(credentials)
      # Construct the service object for interacting with the BigQuery API.
      bigquery_service = build('bigquery', 'v2', credentials=credentials)
  
      try:
          query_request = bigquery_service.jobs()
          query_data = {
              'query': (
                  'SELECT TOP(corpus, 10) as title, '
                  'COUNT(*) as unique_words '
                  'FROM [publicdata:samples.shakespeare];')
          }
  
          query_response = query_request.query(
              projectId=project_id,
              body=query_data).execute()
  
          print('Query Results:')
          for row in query_response['rows']:
              print('\t'.join(field['v'] for field in row['f']))
  
      except HttpError as err:
          print('Error: {}'.format(err.content))
          raise err
  
  
  if __name__ == '__main__':
      parser = argparse.ArgumentParser(
          description=__doc__,
          formatter_class=argparse.RawDescriptionHelpFormatter)
      parser.add_argument('project_id', help='Your Google Cloud Project ID.')
  
      args = parser.parse_args()
  
      main(args.project_id)
  </code></pre>
  
  <p>However, when I run this code through the terminal, I get the following error: </p>
  
  <pre><code>oauth2client.client.ApplicationDefaultCredentialsError: The Application Default Credentials are not available. They are available if running in Google Compute Engine. Otherwise, the environment variable GOOGLE_APPLICATION_CREDENTIALS must be defined pointing to a file defining the credentials. See https://developers.google.com/accounts/docs/application-default-credentials for more information.
  </code></pre>
  
  <p>As you can see in the code, I've tried to set the <code>GOOGLE_APPLICATION_CREDENTIALS</code> as per the link in the error. However, the error persists. Does anyone know what the issue is? </p>
  
  <p>Thank you in advance. </p>