dnspython docker dns issue

docker-compose.yml

version: "2"
services:
  test-service:
    container_name: test-service
    image: busybox
    command: ['/bin/sh', '-c', 'sleep 5']

  test-client-eventlet:
    container_name: test-client-eventlet
    build:
      context: .
      dockerfile: Dockerfile.eventlet
    dns_search: foo.example.com

  test-client-unpatched:
    container_name: test-client-unpatched
    build:
      context: .
      dockerfile: Dockerfile.unpatched
    dns_search: foo.example.com

Dockerfile.eventlet

FROM python:3.4

RUN pip install eventlet

COPY test.py /var/tmp/test.py

CMD [ "python", "/var/tmp/test.py" ]

Dockerfile.unpatched

FROM python:3.4

COPY test.py /var/tmp/test.py

CMD [ "python", "/var/tmp/test.py" ]

test.py

monkeypatched = False
try:
    import eventlet
    eventlet.monkey_patch()
    monkeypatched = True
except ImportError:
    monkeypatched = False

import socket

service_url = 'test-service'


print('### monkeypatched? {} ###'.format(monkeypatched))

ip_list = []
ais = socket.getaddrinfo(service_url, 0, 0, 0, 0)
for result in ais:
    ip_list.append(result[-1][0])
ip_list = list(set(ip_list))
print(ip_list[0])

Expected output:

$ docker-compose up
Starting test-service
Recreating test-client-eventlet
Recreating test-client-unpatched
Attaching to test-service, test-client-eventlet, test-client-unpatched
test-client-eventlet     | ### monkeypatched? True ###
test-client-eventlet    | 172.20.0.2
test-client-unpatched    | ### monkeypatched? False ###
test-client-unpatched    | 172.20.0.2

Actual output:

$ docker-compose up
Starting test-service
Recreating test-client-eventlet
Recreating test-client-unpatched
Attaching to test-service, test-client-eventlet, test-client-unpatched
test-client-eventlet     | ### monkeypatched? True ###
test-client-eventlet     | Traceback (most recent call last):
test-client-eventlet     |   File "/var/tmp/test.py", line 17, in <module>
test-client-eventlet     |     ais = socket.getaddrinfo(service_url, 0, 0, 0, 0)
test-client-eventlet     |   File "/usr/local/lib/python3.4/site-packages/eventlet/support/greendns.py", line 464, in getaddrinfo
test-client-eventlet     |     raise socket.gaierror(socket.EAI_NONAME, 'No address found')
test-client-eventlet     | socket.gaierror: [Errno -2] No address found
test-client-unpatched    | ### monkeypatched? False ###
test-client-unpatched    | 172.20.0.2