Make imagePullPolicy configurable

'Always' is not the best option as it adds round-trip to registry for
every node even if image has already been pulled. Keeping default to be
the same as in Kubernetes would make it conmfortable to use 'latest' tag
during development and proper versioned tag for production-like
environments.

Change-Id: Ifa628e00959bae062bb5bb7e95e071af8babee32

fuel_ccp/config/kubernetes.py

@@ -7,6 +7,7 @@ DEFAULTS = {
         'cert_file': None,
         'insecure': None,
         'cluster_domain': 'cluster.local',
+        'image_pull_policy': None,
     },
 }
 
@@ -22,6 +23,10 @@ SCHEMA = {
             'cert_file': {'anyOf': [{'type': 'string'}, {'type': 'null'}]},
             'insecure': {'anyOf': [{'type': 'string'}, {'type': 'null'}]},
             'cluster_domain': {'type': 'string'},
+            'image_pull_policy': {'oneOf': [
+                {'type': 'null'},
+                {'enum': ['Always', 'IfNotPresent', 'Never']},
+            ]},
         },
     },
 }

fuel_ccp/templates.py

@@ -123,7 +123,7 @@ def serialize_daemon_container_spec(container):
     cont_spec = {
         "name": container["name"],
         "image": images.image_spec(container["image"]),
-        "imagePullPolicy": "Always",
+        "imagePullPolicy": CONF.kubernetes.image_pull_policy,
         "command": _get_start_cmd(container["name"]),
         "volumeMounts": serialize_volume_mounts(container),
         "readinessProbe": {
@@ -152,7 +152,7 @@ def serialize_job_container_spec(container, job):
     return {
         "name": job["name"],
         "image": images.image_spec(container["image"]),
-        "imagePullPolicy": "Always",
+        "imagePullPolicy": CONF.kubernetes.image_pull_policy,
         "command": _get_start_cmd(job["name"]),
         "volumeMounts": serialize_volume_mounts(container, job),
         "env": serialize_env_variables(container)

fuel_ccp/tests/test_templates.py

@@ -8,7 +8,6 @@ class TestDeploy(base.TestCase):
         container = {
             "name": "name_foo",
             "image": "image_foo",
-            "imagePullPolicy": "Always",
             "command": "command_foo",
             "cm_version": 1,
             "env": [{
@@ -30,7 +29,7 @@ class TestDeploy(base.TestCase):
         expected = {
             "name": "name_foo",
             "image": "ccp/image_foo:latest",
-            "imagePullPolicy": "Always",
+            "imagePullPolicy": None,
             "command": [
                 "dumb-init",
                 "/usr/bin/python",