Initial implementation of  svc IP to pod IP translation using DNAT

Change-Id: I6e2f6936636e929ad60150cc67aa6316eef32911
diff --git a/apps/k8s-networking/app/src/main/java/org/onosproject/k8snetworking/impl/K8sGroupRuleManager.java b/apps/k8s-networking/app/src/main/java/org/onosproject/k8snetworking/impl/K8sGroupRuleManager.java
new file mode 100644
index 0000000..aa2b90f
--- /dev/null
+++ b/apps/k8s-networking/app/src/main/java/org/onosproject/k8snetworking/impl/K8sGroupRuleManager.java
@@ -0,0 +1,82 @@
+/*
+ * Copyright 2019-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.
+ */
+package org.onosproject.k8snetworking.impl;
+
+import org.onosproject.core.ApplicationId;
+import org.onosproject.core.CoreService;
+import org.onosproject.k8snetworking.api.K8sGroupRuleService;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.group.DefaultGroupDescription;
+import org.onosproject.net.group.GroupBucket;
+import org.onosproject.net.group.GroupBuckets;
+import org.onosproject.net.group.GroupDescription;
+import org.onosproject.net.group.GroupDescription.Type;
+import org.onosproject.net.group.GroupService;
+import org.osgi.service.component.annotations.Activate;
+import org.osgi.service.component.annotations.Component;
+import org.osgi.service.component.annotations.Deactivate;
+import org.osgi.service.component.annotations.Reference;
+import org.osgi.service.component.annotations.ReferenceCardinality;
+import org.slf4j.Logger;
+
+import java.util.List;
+
+import static org.onosproject.k8snetworking.api.Constants.K8S_NETWORKING_APP_ID;
+import static org.onosproject.k8snetworking.util.K8sNetworkingUtil.getGroupKey;
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * Sets group table rules directly using GroupService.
+ */
+@Component(immediate = true, service = K8sGroupRuleService.class)
+public class K8sGroupRuleManager implements K8sGroupRuleService {
+
+    private final Logger log = getLogger(getClass());
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected GroupService groupService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY)
+    protected CoreService coreService;
+
+    private ApplicationId appId;
+
+    @Activate
+    protected void activate() {
+        appId = coreService.registerApplication(K8S_NETWORKING_APP_ID);
+        coreService.registerApplication(K8S_NETWORKING_APP_ID);
+
+        log.info("Started");
+    }
+
+    @Deactivate
+    protected void deactivate() {
+        log.info("Stopped");
+    }
+
+    @Override
+    public void setRule(ApplicationId appId, DeviceId deviceId, int groupId,
+                        Type type, List<GroupBucket> buckets, boolean install) {
+        GroupDescription groupDesc = new DefaultGroupDescription(deviceId,
+                type, new GroupBuckets(buckets), getGroupKey(groupId), groupId, appId);
+
+        if (install) {
+            groupService.addGroup(groupDesc);
+        } else {
+            groupService.removeGroup(deviceId, getGroupKey(groupId), appId);
+        }
+    }
+}