old_contents: #!/usr/bin/env python
  
  import os
  from six.moves.urllib_parse import urlparse
  
  
  def from_docker_envvars(config):
      # linked postgres database (link name 'pg' or 'postgres')
      if 'PG_PORT' in os.environ:
          pg_url = urlparse(os.environ['PG_PORT'])
  
          if not pg_url.scheme == 'tcp':
              raise ValueError('Only tcp scheme supported for postgres')
  
          host, port = pg_url.netloc.split(':')
  
          uri = 'postgres://{user}:{password}@{host}:{port}/{database}'.format(
              user=os.environ.get('PG_ENV_POSTGRES_USER', 'postgres'),
              password=os.environ.get('PG_ENV_POSTGRES_PASSWORD', ''),
              host=host,
              port=port,
              database=os.environ.get('PG_ENV_POSTGRES_DB'))
  
          config['SQLALCHEMY_DATABASE_URI'] = uri
  
      if 'REDIS_PORT' in os.environ:
          redis_url = urlparse(os.environ['REDIS_PORT'])
  
          if not redis_url.scheme == 'tcp':
              raise ValueError('Only tcp scheme supported for redis')
  
          host, port = redis_url.netloc.split(':')
  
          uri = 'redis://{host}:{port}/0'.format(host=host, port=port, )
  
          config['REDIS_URL'] = uri
          config['REDIS_HOST'] = host
          config['REDIS_PORT'] = int(port)
  
new_contents: #!/usr/bin/env python
  
  import os
  from six.moves.urllib_parse import urlparse
  
  
  def from_docker_envvars(config):
      # linked postgres database (link name 'pg' or 'postgres')
      if 'PG_PORT' in os.environ:
          pg_url = urlparse(os.environ['PG_PORT'])
  
          if not pg_url.scheme == 'tcp':
              raise ValueError('Only tcp scheme supported for postgres')
  
          host, port = pg_url.netloc.split(':')
  
          uri = 'postgres://{user}:{password}@{host}:{port}/{database}'.format(
              user=os.environ.get('PG_ENV_POSTGRES_USER', 'postgres'),
              password=os.environ.get('PG_ENV_POSTGRES_PASSWORD', ''),
              host=host,
              port=port,
              database=os.environ.get('PG_ENV_POSTGRES_DB', 'postgres'))
  
          config['SQLALCHEMY_DATABASE_URI'] = uri
  
      if 'REDIS_PORT' in os.environ:
          redis_url = urlparse(os.environ['REDIS_PORT'])
  
          if not redis_url.scheme == 'tcp':
              raise ValueError('Only tcp scheme supported for redis')
  
          host, port = redis_url.netloc.split(':')
  
          uri = 'redis://{host}:{port}/0'.format(host=host, port=port, )
  
          config['REDIS_URL'] = uri
          config['REDIS_HOST'] = host
          config['REDIS_PORT'] = int(port)
  
subject: Use correct database name instead of None when not supplied.