feat: support to reference resource in devicelink

- reference the same Namespace's configmap/secret
- reference the downward API for devicelink
- adjust the related docs

README.md

@@ -9,6 +9,10 @@ Octopus is an edge device management system based on Kubernetes, it is very ligh
 - [Idea](#idea)
 - [Workflow](#workflow)
 - [Walkthrough](#walkthrough)
+    + [Deploy Octopus](#deploy-octopus)
+    + [Deploy Device Model & Device Adaptor](#deploy-device-model--device-adaptor)
+    + [Create DeviceLink](#create-devicelink)
+    + [Manage Device](#manage-device)
 - [Documentation](#documentation)
 - [License](#license)
 
@@ -79,7 +83,7 @@ In this walkthrough, we try to use Octopus to manage a dummy device. We will per
 
 1. Deploy Octopus
 1. Deploy Device Model & Device Adaptor
-1. Create Device Link
+1. Create DeviceLink
 1. Manage Device
 
 ### Deploy Octopus
@@ -257,15 +261,17 @@ octopus-adaptor-dummy-manager-rolebinding              43s
 
 ```
 
-### Create Device Link
+### Create DeviceLink
 
-Next, we are going to connect a device via `DeviceLink`. A link consists of 3 parts: `Adaptor`, `Model` and `Device spec`:
+Next, we are going to connect a device via `DeviceLink`. A link mainly consists of 3 fields: `adaptor`, `model` and `template(device spec)`:
 
-- `Adaptor` describes how to access the device, this connection process calls adaptation. In order to connect a device, we should indicate the name of the adaptor, the name of the device-connectable node and the parameters of this connection.
-- `Model` describes the model of device, it is the [TypeMeta](https://github.com/kubernetes/apimachinery/blob/master/pkg/apis/meta/v1/types.go) of the device model CRD.
-- `Device spec` describes the desired status of device, it is determined by the device model CRD. 
+- `adaptor` describes how to access the device, this accessing process calls **Adaptation**. In order to adapt a device, we need to indicate the name of the adaptor and the name of the device-connectable node.
+- `model` describes the model of device, it is the [TypeMeta](https://github.com/kubernetes/apimachinery/blob/master/pkg/apis/meta/v1/types.go) of the device model CRD.
+- `template(device spec)` describes the desired status of device, it is determined by the device model CRD.
 
-We can imagine that there is a device named `living-room-fan` on the `edge-worker` node, we can try to connect it in.
+In addition, we can also use the `references` field to refer the [ConfigMap](https://kubernetes.io/docs/concepts/configuration/configmap/) and [Secret](https://kubernetes.io/docs/concepts/configuration/secret/) under the same Namespace, even use the downward API to fetch the information in `DeviceLink`.
+
+We can imagine that there is a device named `living-room-fan` on the `edge-worker` node, and then we can connect it by Octopus:
 
 ```yaml
 apiVersion: edge.cattle.io/v1alpha1
@@ -292,7 +298,7 @@ spec:
 
 ```
 
-There are [several states](./docs/octopus/state_of_devicelink.md) of a link, if we found the **DeviceConnected** `PHASE` is on **Healthy** `STATUS`, we can query the same name instance of device model CRD, now the device is in our cluster:
+After deployed the above `DeviceLink` into a cluster, we could find that there are [several states](./docs/octopus/state_of_devicelink.md) of a link. If the **DeviceConnected** `PHASE` is on **Healthy** `STATUS`, we can query the same name instance of device model CRD, now the device is in our cluster:
 
 ```shell script
 $ kubectl get devicelink living-room-fan -n default

api/v1alpha1/devicelink_types.go

@@ -1,21 +1,96 @@
 package v1alpha1
 
 import (
+	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 )
 
+// DeviceLinkReferenceSecretSource defines the source of a same name Secret instance.
+type DeviceLinkReferenceSecretSource struct {
+	// Specifies the name of the Secret in the same Namespace to use.
+	// +kubebuilder:validation:Required
+	Name string `json:"name"`
+
+	// Specifies the key of the Secret's data.
+	// If not specified, all keys of the Secret will be projected into the parameter values.
+	// If specified, the listed keys will be projected into the parameter value.
+	// If a key is specified which is not present in the Secret,
+	// the connection will error unless it is marked optional.
+	// +optional
+	Items []string `json:"items,omitempty"`
+}
+
+// DeviceLinkReferenceConfigMapSource defines the source of a same name ConfigMap instance.
+type DeviceLinkReferenceConfigMapSource struct {
+	// Specifies the name of the ConfigMap in the same Namespace to use.
+	// +kubebuilder:validation:Required
+	Name string `json:"name"`
+
+	// Specifies the key of the ConfigMap's data.
+	// If not specified, all keys of the ConfigMap will be projected into the parameter values.
+	// If specified, the listed keys will be projected into the parameter value.
+	// If a key is specified which is not present in the ConfigMap,
+	// the connection will error unless it is marked optional.
+	// +optional
+	Items []string `json:"items,omitempty"`
+}
+
+// DeviceLinkReferenceDownwardAPISourceItem defines the downward API item for projecting the DeviceLink.
+type DeviceLinkReferenceDownwardAPISourceItem struct {
+	// Specifies the key of the downward API's data.
+	// +kubebuilder:validation:Required
+	Name string `json:"name"`
+
+	// Specifies that how to select a field of the DeviceLink,
+	// only annotations, labels, name, namespace and status are supported.
+	// +kubebuilder:validation:Required
+	FieldRef *corev1.ObjectFieldSelector `json:"fieldRef"`
+}
+
+// DeviceLinkReferenceDownwardAPISource defines the downward API for projecting the DeviceLink.
+type DeviceLinkReferenceDownwardAPISource struct {
+	// Specifies a list of downward API.
+	// +kubebuilder:validation:MinItems=1
+	Items []DeviceLinkReferenceDownwardAPISourceItem `json:"items"`
+}
+
+// DeviceLinkReferenceSource defines the parameter source.
+type DeviceLinkReferenceSource struct {
+	// Secret represents a Secret of the same Namespace that should populate this connection.
+	// +optional
+	Secret *DeviceLinkReferenceSecretSource `json:"secret,omitempty"`
+
+	// ConfigMap represents a ConfigMap of the same Namespace that should populate this connection.
+	// +optional
+	ConfigMap *DeviceLinkReferenceConfigMapSource `json:"configMap,omitempty"`
+
+	// DownwardAPI represents the downward API about the DeviceLink.¬
+	// +optional
+	DownwardAPI *DeviceLinkReferenceDownwardAPISource `json:"downwardAPI,omitempty"`
+}
+
+// DeviceLinkReference defines the parameter that should be passed to the adaptor during connecting.
+type DeviceLinkReference struct {
+	DeviceLinkReferenceSource `json:",inline"`
+
+	// Specifies the name of the parameter.
+	Name string `json:"name,omitempty"`
+}
+
 // DeviceAdaptor defines the properties of device adaptor
 type DeviceAdaptor struct {
 	// Specifies the node of adaptor to be matched.
 	// +optional
 	Node string `json:"node,omitempty"`
 
 	// Specifies the name of adaptor to be used.
-	// +optional
+	// +kubebuilder:validation:Required
 	Name string `json:"name,omitempty"`
 
-	// Specifies the parameter of adaptor to be used.
+	// [Deprecated] Specifies the parameter of adaptor to be used.
+	// This field has been deprecated, it should define the connection parameter
+	// as a part of device model.
 	// +kubebuilder:pruning:PreserveUnknownFields
 	// +optional
 	Parameters *runtime.RawExtension `json:"parameters,omitempty"`
@@ -96,6 +171,10 @@ type DeviceLinkSpec struct {
 	// +kubebuilder:validation:Required
 	Model metav1.TypeMeta `json:"model"`
 
+	// Specifies the references of device to be used.
+	// +optional
+	References []DeviceLinkReference `json:"references,omitempty"`
+
 	// Describe the device that will be created.
 	// +kubebuilder:validation:Required
 	Template DeviceTemplateSpec `json:"template"`