add app-scope config

Author: hongchaodeng

appscope_configuration.md

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+# AppScope Configuration
+
+This section describes how application scope can be set up using app-scope configuration.
+
+An app scope needs to be set up before referenced/used by each deployment of components. To set up an app scope, we deploy an app-scope configuration.
+
+An app-scope configuration (abbr. `scope config`) is managed by the _app operator_ role, and provides information specific to the current set-up of an app scope.
+
+## Defining an AppScope Configuration
+
+### Top-Level Attributes
+
+The top-level attributes of an app-scope config define its apiVersion, kind, metadata, and spec.
+
+| Attribute | Type | Required | Default Value | Description |
+|-----------|------|----------|---------------|-------------|
+| `apiVersion` | `string` | Y || The API version of the specification in use. At present only `core.hydra.io/v1alpha1` is defined. |
+| `kind` | `string` | Y || The string `AppScopeConfiguration` |
+| `metadata` | [`Metadata`](#metadata) | Y | | AppScope configuration metadata. |
+| `spec`| [`Spec`](#spec) | Y || A container for exposing configuration attributes. |
+
+### Metadata
+
+Metadata describes this trait. The metadata section is defined in [Section 3](3.component_model.md#metadata).
+
+
+### Spec
+The specification defines three major things: Parameters that can be overridden at deployment time, a set of scopes to create, and component instances to create.
+
+| Attribute | Type | Required | Default Value | Description |
+|-----------|------|----------|---------------|-------------|
+| `appScopeType` | `string` | Y | | The type of the app-scope to create an instance of. |
+| `properties` | [`Properties`](#properties) | N | | The properties attached to this scope. |
+
+### Properties
+
+A properties object is an object whose structure is determined by the scope property schema. It may be a simple value, or it may be a complex object. Properties are validated against the schema appropriate for the trait or scope. For example, if a trait defines a schema for properties that requires an array of integers with at least one member, the `properties` object is expected to be an array of integers with at least one member. During validation of the `properties` object, the trait's property schema will be applied.
+
+If no schema is supplied, a property will be passed to the trait runtime without structural validation. As long as it parses as YAML or JSON, it will be considered valid.
+
+## Example
+The following is an example of a complete YAML file that illustrates the configurational elements above:
+
+```yaml
+apiVersion: core.hydra.io/v1alpha1
+kind: AppScopeConfiguration
+metadata:
+  name: public-vpc
+spec:
+  appScopeType: core.hydra.io/v1alpha1.Network
+  properties:
+  - name: network-id
+    value: myNetwork
+  - name: subnet-id
+    value: public-subnet
+  - name: gateway-type
+    value: public
+
+---
+apiVersion: core.hydra.io/v1alpha1
+kind: AppScopeConfiguration
+metadata:
+  name: private-vpc
+spec:
+  appScopeType: core.hydra.io/v1alpha1.Network
+  properties:
+  - name: network-id
+    value: myNetwork
+  - name: subnet-id
+    value: private-subnet
+  - name: gateway-type
+    value: nat
+```