VOL-1405 : First submission for read-only core

- Most of the logic was copied from the read-write implementation
- Added missing Get/List calls
- Added necessary targets in Makefile
- Added docker and k8s manifests

Amendments:

- Removed more unecessary code.
- Removed refs to kafka
- Adjustements to reflect comments
- Removed refs to kafka in manifests

Change-Id: Ife2ca13d3ae428923825f7c19d42359d60406839
diff --git a/ro_core/core/device_agent.go b/ro_core/core/device_agent.go
new file mode 100644
index 0000000..1ae1275
--- /dev/null
+++ b/ro_core/core/device_agent.go
@@ -0,0 +1,193 @@
+/*
+ * Copyright 2018-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 core
+
+import (
+	"context"
+	"github.com/gogo/protobuf/proto"
+	"github.com/opencord/voltha-go/common/log"
+	"github.com/opencord/voltha-go/db/model"
+	"github.com/opencord/voltha-go/protos/voltha"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+	"sync"
+)
+
+type DeviceAgent struct {
+	deviceId         string
+	deviceType       string
+	lastData         *voltha.Device
+	deviceMgr        *DeviceManager
+	clusterDataProxy *model.Proxy
+	exitChannel      chan int
+	lockDevice       sync.RWMutex
+}
+
+//newDeviceAgent creates a new device agent along as creating a unique ID for the device and set the device state to
+//preprovisioning
+func newDeviceAgent(device *voltha.Device, deviceMgr *DeviceManager, cdProxy *model.Proxy) *DeviceAgent {
+	var agent DeviceAgent
+	agent.deviceId = device.Id
+	agent.deviceType = device.Type
+	agent.lastData = device
+	agent.deviceMgr = deviceMgr
+	agent.exitChannel = make(chan int, 1)
+	agent.clusterDataProxy = cdProxy
+	agent.lockDevice = sync.RWMutex{}
+	return &agent
+}
+
+// start save the device to the data model and registers for callbacks on that device
+func (agent *DeviceAgent) start(ctx context.Context) {
+	log.Debugw("starting-device-agent", log.Fields{"device": agent.lastData})
+	agent.lockDevice.Lock()
+	defer agent.lockDevice.Unlock()
+	log.Debug("device-agent-started")
+}
+
+// stop stops the device agent.  Not much to do for now
+func (agent *DeviceAgent) stop(ctx context.Context) {
+	agent.lockDevice.Lock()
+	defer agent.lockDevice.Unlock()
+	log.Debug("stopping-device-agent")
+	agent.exitChannel <- 1
+	log.Debug("device-agent-stopped")
+}
+
+// GetDevice retrieves the latest device information from the data model
+func (agent *DeviceAgent) getDevice() (*voltha.Device, error) {
+	agent.lockDevice.Lock()
+	defer agent.lockDevice.Unlock()
+	if device := agent.clusterDataProxy.Get("/devices/"+agent.deviceId, 1, false, ""); device != nil {
+		if d, ok := device.(*voltha.Device); ok {
+			cloned := proto.Clone(d).(*voltha.Device)
+			return cloned, nil
+		}
+	}
+	return nil, status.Errorf(codes.NotFound, "device-%s", agent.deviceId)
+}
+
+// getDeviceWithoutLock is a helper function to be used ONLY by any device agent function AFTER it has acquired the device lock.
+// This function is meant so that we do not have duplicate code all over the device agent functions
+func (agent *DeviceAgent) getDeviceWithoutLock() (*voltha.Device, error) {
+	if device := agent.clusterDataProxy.Get("/devices/"+agent.deviceId, 1, false, ""); device != nil {
+		if d, ok := device.(*voltha.Device); ok {
+			cloned := proto.Clone(d).(*voltha.Device)
+			return cloned, nil
+		}
+	}
+	return nil, status.Errorf(codes.NotFound, "device-%s", agent.deviceId)
+}
+
+// getPorts retrieves the ports information of the device based on the port type.
+func (agent *DeviceAgent) getPorts(ctx context.Context, portType voltha.Port_PortType) *voltha.Ports {
+	log.Debugw("getPorts", log.Fields{"id": agent.deviceId, "portType": portType})
+	ports := &voltha.Ports{}
+	if device, _ := agent.deviceMgr.GetDevice(agent.deviceId); device != nil {
+		for _, port := range device.Ports {
+			if port.Type == portType {
+				ports.Items = append(ports.Items, port)
+			}
+		}
+	}
+	return ports
+}
+
+// ListDevicePorts retrieves the ports information for a particular device.
+func (agent *DeviceAgent) ListDevicePorts(ctx context.Context) (*voltha.Ports, error) {
+	log.Debugw("ListDevicePorts", log.Fields{"id": agent.deviceId})
+	ports := &voltha.Ports{}
+	if device, _ := agent.deviceMgr.GetDevice(agent.deviceId); device != nil {
+		for _, entry := range device.GetPorts() {
+			ports.Items = append(ports.Items, entry)
+		}
+		return ports, nil
+	}
+	return nil, status.Errorf(codes.NotFound, "device-%s", agent.deviceId)
+}
+
+// ListDevicePmConfigs retrieves the ports information for a particular device.
+func (agent *DeviceAgent) ListDevicePmConfigs(ctx context.Context) (*voltha.PmConfigs, error) {
+	log.Debugw("ListDevicePmConfigs", log.Fields{"id": agent.deviceId})
+	if device, _ := agent.deviceMgr.GetDevice(agent.deviceId); device != nil {
+		return device.GetPmConfigs(), nil
+	}
+	return nil, status.Errorf(codes.NotFound, "device-%s", agent.deviceId)
+}
+
+// ListDeviceFlows retrieves the ports information for a particular device.
+func (agent *DeviceAgent) ListDeviceFlows(ctx context.Context) (*voltha.Flows, error) {
+	log.Debugw("ListDeviceFlows", log.Fields{"id": agent.deviceId})
+	if device, _ := agent.deviceMgr.GetDevice(agent.deviceId); device != nil {
+		return device.GetFlows(), nil
+	}
+	return nil, status.Errorf(codes.NotFound, "device-%s", agent.deviceId)
+}
+
+// ListDeviceFlows retrieves the ports information for a particular device.
+func (agent *DeviceAgent) ListDeviceFlowGroups(ctx context.Context) (*voltha.FlowGroups, error) {
+	log.Debugw("ListDeviceFlowGroups", log.Fields{"id": agent.deviceId})
+	if device, _ := agent.deviceMgr.GetDevice(agent.deviceId); device != nil {
+		return device.GetFlowGroups(), nil
+	}
+	return nil, status.Errorf(codes.NotFound, "device-%s", agent.deviceId)
+}
+
+// GetImageDownloadStatus retrieves the download status of an image of a particular device.
+func (agent *DeviceAgent) GetImageDownloadStatus(ctx context.Context, imageName string) (*voltha.ImageDownload, error) {
+	log.Debugw("GetImageDownloadStatus", log.Fields{"id": agent.deviceId})
+	if device, _ := agent.deviceMgr.GetDevice(agent.deviceId); device != nil {
+		for _, img := range device.GetImageDownloads() {
+			if img.GetName() == imageName {
+				return img, nil
+			}
+		}
+		return nil, status.Errorf(codes.NotFound, "device-%s, image-%s", agent.deviceId, imageName)
+	}
+	return nil, status.Errorf(codes.NotFound, "device-%s", agent.deviceId)
+}
+
+// GetImageDownload retrieves the image download for a particular device.
+func (agent *DeviceAgent) GetImageDownload(ctx context.Context, imageName string) (*voltha.ImageDownload, error) {
+	log.Debugw("GetImageDownload", log.Fields{"id": agent.deviceId})
+	if device, _ := agent.deviceMgr.GetDevice(agent.deviceId); device != nil {
+		for _, img := range device.GetImageDownloads() {
+			if img.GetName() == imageName {
+				return img, nil
+			}
+		}
+		return nil, status.Errorf(codes.NotFound, "device-%s, image-%s", agent.deviceId, imageName)
+	}
+	return nil, status.Errorf(codes.NotFound, "device-%s", agent.deviceId)
+}
+
+// ListImageDownloads retrieves the image downloads for a particular device.
+func (agent *DeviceAgent) ListImageDownloads(ctx context.Context) (*voltha.ImageDownloads, error) {
+	log.Debugw("ListImageDownloads", log.Fields{"id": agent.deviceId})
+	if device, _ := agent.deviceMgr.GetDevice(agent.deviceId); device != nil {
+		return &voltha.ImageDownloads{Items: device.GetImageDownloads()}, nil
+	}
+	return nil, status.Errorf(codes.NotFound, "device-%s", agent.deviceId)
+}
+
+// GetImages retrieves the list of images for a particular device.
+func (agent *DeviceAgent) GetImages(ctx context.Context) (*voltha.Images, error) {
+	log.Debugw("GetImages", log.Fields{"id": agent.deviceId})
+	if device, _ := agent.deviceMgr.GetDevice(agent.deviceId); device != nil {
+		return device.GetImages(), nil
+	}
+	return nil, status.Errorf(codes.NotFound, "device-%s", agent.deviceId)
+}
\ No newline at end of file