CORD-3224 Implement KubernetesResourceInstance

Change-Id: Ic3c7691aa16a20c0d7d69994fef1ad8ac6d1ca44
diff --git a/xos/synchronizer/steps/sync_kubernetesresourceinstance.py b/xos/synchronizer/steps/sync_kubernetesresourceinstance.py
new file mode 100644
index 0000000..60174bb
--- /dev/null
+++ b/xos/synchronizer/steps/sync_kubernetesresourceinstance.py
@@ -0,0 +1,80 @@
+
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+    sync_kubernetesresourceinstance.py
+
+    Synchronize KubernetesResourceInstance.
+
+    This sync_step is instantiates generic resources by executing them with `kubectl`.
+"""
+
+import os
+import subprocess
+import tempfile
+from synchronizers.new_base.syncstep import SyncStep
+from synchronizers.new_base.modelaccessor import KubernetesResourceInstance
+
+from xosconfig import Config
+from multistructlog import create_logger
+
+log = create_logger(Config().get('logging'))
+
+class SyncKubernetesResourceInstance(SyncStep):
+
+    """
+        SyncKubernetesResourceInstance
+
+        Implements sync step for syncing kubernetes resource instances. These objects are basically a yaml blob that
+        is passed to `kubectl`.
+    """
+
+    provides = [KubernetesResourceInstance]
+    observes = KubernetesResourceInstance
+    requested_interval = 0
+
+    def __init__(self, *args, **kwargs):
+        super(SyncKubernetesResourceInstance, self).__init__(*args, **kwargs)
+
+    def run_kubectl(self, operation, recipe):
+        (tmpfile, fn)=tempfile.mkstemp()
+        os.write(tmpfile, recipe)
+        os.close(tmpfile)
+        try:
+            p = subprocess.Popen(args=["/usr/local/bin/kubectl", operation, "-f", fn],
+                                 stdin=None,
+                                 stderr=subprocess.PIPE,
+                                 stdout=subprocess.PIPE,
+                                 close_fds=True)
+            (stdout, stderr) = p.communicate()
+            log.info("kubectl completed", stderr=stderr, stdout=stdout, recipe=recipe)
+            if p.returncode!=0:
+                raise Exception("Process failed with returncode %s" % p.returncode)
+        finally:
+            os.remove(fn)
+
+    def sync_record(self, o):
+        self.run_kubectl("apply", o.resource_definition)
+        if (o.kubectl_state == "created"):
+            o.kubectl_state = "updated"
+        else:
+            o.kubectl_state = "created"
+        o.save(update_fields=["kubectl_state"])
+
+    def delete_record(self, o):
+        if o.kubectl_state in ["created", "updated"]:
+            self.run_kubectl("delete", o.resource_definition)
+            o.kubectl_state="deleted"
+            o.save(update_fields=["kubectl_state"])