Initial support for multi kubernetes clusters for k8s nodes

Change-Id: I6ca132898f8e157e0583de38a637fdc135f21d6f
diff --git a/apps/k8s-node/api/src/main/java/org/onosproject/k8snode/api/K8sHost.java b/apps/k8s-node/api/src/main/java/org/onosproject/k8snode/api/K8sHost.java
new file mode 100644
index 0000000..c93d4d1
--- /dev/null
+++ b/apps/k8s-node/api/src/main/java/org/onosproject/k8snode/api/K8sHost.java
@@ -0,0 +1,109 @@
+/*
+ * Copyright 2020-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.k8snode.api;
+
+import org.onlab.packet.IpAddress;
+import org.onosproject.net.DeviceId;
+
+import java.util.Set;
+
+/**
+ * Representation of a host used in k8s-networking service.
+ */
+public interface K8sHost {
+
+    /**
+     * Returns the host IP address. Note that the host IP address is unique, and
+     * will be used as an identifier for the host.
+     *
+     * @return host IP address
+     */
+    IpAddress hostIp();
+
+    /**
+     * A set of node names included in this host.
+     *
+     * @return node names
+     */
+    Set<String> nodeNames();
+
+    /**
+     * Returns kubernetes host state.
+     *
+     * @return host state
+     */
+    K8sHostState state();
+
+    /**
+     * Returns the OVSDB device ID of the node.
+     *
+     * @return ovsdb device ID
+     */
+    DeviceId ovsdb();
+
+    /**
+     * Returns new kubernetes host instance with given state.
+     *
+     * @param newState updated state
+     * @return updated kubernetes host
+     */
+    K8sHost updateState(K8sHostState newState);
+
+    /**
+     * Returns new kuberentes host instance with given node names.
+     *
+     * @param nodeNames a set of node names
+     * @return updated kubernetes host
+     */
+    K8sHost updateNodeNames(Set<String> nodeNames);
+
+    /**
+     * Builder of new host entity.
+     */
+    interface Builder {
+
+        /**
+         * Builds an immutable kubernetes host instance.
+         *
+         * @return kubernetes host instance
+         */
+        K8sHost build();
+
+        /**
+         * Returns kubernetes host builder with supplied host IP address.
+         *
+         * @param hostIp host IP address
+         * @return kubernetes host builder
+         */
+        Builder hostIp(IpAddress hostIp);
+
+        /**
+         * Returns kubernetes host builder with supplied node names.
+         *
+         * @param nodeNames node names
+         * @return kubernetes host builder
+         */
+        Builder nodeNames(Set<String> nodeNames);
+
+        /**
+         * Returns kubernetes host builder with supplied host state.
+         *
+         * @param state host state
+         * @return kubernetes host builder
+         */
+        Builder state(K8sHostState state);
+    }
+}