How to use the dockerspawner.SystemUserSpawner function in dockerspawner

from tornado import gen
from dockerspawner import DockerSpawner, SystemUserSpawner

# urllib3 complains that we're making unverified HTTPS connections to swarm,
# but this is ok because we're connecting to swarm via 127.0.0.1. I don't
# actually want swarm listening on a public port, so I don't want to connect
# to swarm via the host's FQDN, which means we can't do fully verified HTTPS
# connections. To prevent the warning from appearing over and over and over
# again, I'm just disabling it for now.
import requests
requests.packages.urllib3.disable_warnings()


class SwarmSpawner(SystemUserSpawner):

    container_ip = '0.0.0.0'

    @gen.coroutine
    def lookup_node_name(self):
        """Find the name of the swarm node that the container is running on."""
        containers = yield self.docker('containers', all=True)
        for container in containers:
            if container['Id'] == self.container_id:
                name, = container['Names']
                node, container_name = name.lstrip("/").split("/")
                raise gen.Return(node)

    @gen.coroutine
    def start(self, image=None, extra_create_kwargs=None, extra_host_config=None):
        # look up mapping of node names to ip addresses

from tornado import gen
from dockerspawner import DockerSpawner, SystemUserSpawner

# urllib3 complains that we're making unverified HTTPS connections to swarm,
# but this is ok because we're connecting to swarm via 127.0.0.1. I don't
# actually want swarm listening on a public port, so I don't want to connect
# to swarm via the host's FQDN, which means we can't do fully verified HTTPS
# connections. To prevent the warning from appearing over and over and over
# again, I'm just disabling it for now.
import requests
requests.packages.urllib3.disable_warnings()


class SwarmSpawner(SystemUserSpawner):

    container_ip = '0.0.0.0'

    def _user_id_default(self):
        return 2000

    @gen.coroutine
    def lookup_node_name(self):
        """Find the name of the swarm node that the container is running on."""
        containers = yield self.docker('containers', all=True)
        for container in containers:
            if container['Id'] == self.container_id:
                name, = container['Names']
                node, container_name = name.lstrip("/").split("/")
                raise gen.Return(node)