gistfile1.py

def _launch_cluster_instances(self, instance_templates):
    singleton_hosts = []
    for instance_template in instance_templates:
      instance_template.add_env_strings(singleton_hosts)
      instances = self._launch_instances(instance_template)
      if instance_template.number == 1:
        if len(instances) != 1:
          logger.error("Expected a single '%s' instance, but found %s.",
                       "".join(instance_template.roles), len(instances))
          return
        else:
          for role in instance_template.roles:
            singleton_host_env = "%s_HOST=%s" % \
              (self._sanitize_role_name(role),
               instances[0].public_ip)
            singleton_hosts.append(singleton_host_env)