config: Bump Hyper-V condition from root.path to root itself

Don't require users targetting Hyper-V to set an empty object ("root":
{}).  This also avoids confusion about whether you can set
root.readonly without setting root.path (you can't).

Signed-off-by: W. Trevor King <wking@tremily.us>

config.md

@@ -26,17 +26,17 @@ For example, if a configuration is compliant with version 1.1 of this specificat
 
 ## <a name="configRoot" />Root
 
-**`root`** (object, REQUIRED) specifies the container's root filesystem.
-
-* **`path`** (string, OPTIONAL) Specifies the path to the root filesystem for the container. The path is either an absolute path or a relative path to the bundle.
-
+**`root`** (object, OPTIONAL) specifies the container's root filesystem.
     On Windows, for Windows Server Containers, this field is REQUIRED. For Hyper-V Containers, this field MUST be omitted.
 
     On all other platforms, this field is REQUIRED.
 
+* **`path`** (string, REQUIRED) Specifies the path to the root filesystem for the container.
+    The path is either an absolute path or a relative path to the bundle.
     On Linux, for example, with a bundle at `/to/bundle` and a root filesystem at `/to/bundle/rootfs`, the `path` value can be either `/to/bundle/rootfs` or `rootfs`.
 
-    If defined, a directory MUST exist at the path declared by the field.
+    A directory MUST exist at the path declared by the field.
+
 * **`readonly`** (bool, OPTIONAL) If true then the root filesystem MUST be read-only inside the container, defaults to false. On Windows, this field must be omitted or false.
 
 ### Example

schema/config-schema.json

@@ -59,6 +59,9 @@
             "description": "Configures the container's root filesystem.",
             "id": "https://opencontainers.org/schema/bundle/root",
             "type": "object",
+            "required": [
+                "path"
+            ],
             "properties": {
                 "path": {
                     "id": "https://opencontainers.org/schema/bundle/root/path",
@@ -233,7 +236,6 @@
     },
     "required": [
         "ociVersion",
-        "platform",
-        "root"
+        "platform"
     ]
 }

specs-go/config.go

@@ -11,7 +11,7 @@ type Spec struct {
 	// Process configures the container process.
 	Process *Process `json:"process,omitempty"`
 	// Root configures the container's root filesystem.
-	Root Root `json:"root"`
+	Root *Root `json:"root,omitempty"`
 	// Hostname configures the container's hostname.
 	Hostname string `json:"hostname,omitempty"`
 	// Mounts configures additional mounts (on top of Root).
@@ -96,7 +96,7 @@ type User struct {
 // Root contains information about the container's root filesystem on the host.
 type Root struct {
 	// Path is the absolute path to the container's root filesystem.
-	Path string `json:"path,omitempty"`
+	Path string `json:"path"`
 	// Readonly makes the root filesystem for the container readonly before the process is executed.
 	Readonly bool `json:"readonly,omitempty"`
 }