ref(registry): remove simpleflock and depend on Docker 1.9 minimum (#1090)

Concurrent pull issue was resolved in 1.9 (moby/moby#9718) and Kubernetes is validated against that as well

Author: helgi

rootfs/registry/dockerclient.py

@@ -7,7 +7,6 @@
 import backoff
 from django.conf import settings
 from rest_framework.exceptions import PermissionDenied
-from simpleflock import SimpleFlock
 
 import docker
 import docker.constants
@@ -25,8 +24,6 @@ class RegistryException(Exception):
 class DockerClient(object):
     """Use the Docker API to pull, tag, build, and push images to deis-registry."""
 
-    FLOCKFILE = '/tmp/controller-pull'
-
     def __init__(self):
         timeout = os.environ.get('DOCKER_CLIENT_TIMEOUT', docker.constants.DEFAULT_TIMEOUT_SECONDS)
         self.client = docker.Client(version='auto', timeout=timeout)
@@ -123,9 +120,8 @@ def pull(self, repo, tag):
         """Pull a Docker image into the local storage graph."""
         check_blacklist(repo)
         logger.info("Pulling Docker image {}:{}".format(repo, tag))
-        with SimpleFlock(self.FLOCKFILE, timeout=1200):
-            stream = self.client.pull(repo, tag=tag, stream=True, decode=True)
-            log_output(stream, 'pull', repo, tag)
+        stream = self.client.pull(repo, tag=tag, stream=True, decode=True)
+        log_output(stream, 'pull', repo, tag)
 
     @backoff.on_exception(backoff.expo, Exception, max_tries=3)
     def push(self, repo, tag):

rootfs/requirements.txt

@@ -15,6 +15,5 @@ pyOpenSSL==16.1.0
 pytz==2016.6.1
 requests==2.11.1
 requests-toolbelt==0.7.0
-simpleflock==0.0.3
 jsonschema==2.5.1
 idna==2.1