Simply platform field

Close: #725

See discussion in #830 , the full platform can be maintained
in image-spec, but since we have platform-specific configurations
in runtime-spec, I think it makes sence we keep a general simple
definition for platform.

Signed-off-by: Qiang Huang <[email protected]>

Author: hqhq

config.md

@@ -304,46 +304,32 @@ For Windows based systems the user structure has the following fields:
 
 ## <a name="configPlatform" />Platform
 
-**`platform`** (object, REQUIRED) specifies the configuration's target platform.
-
-* **`os`** (string, REQUIRED) specifies the operating system family of the container configuration's specified [`root`](#root) file system bundle.
-  The runtime MUST generate an error if it does not support the specified **`os`**.
-  Bundles SHOULD use, and runtimes SHOULD understand, **`os`** entries listed in the Go Language document for [`GOOS`][go-environment].
-  If an operating system is not included in the `GOOS` documentation, it SHOULD be submitted to this specification for standardization.
-* **`arch`** (string, REQUIRED) specifies the instruction set for which the binaries in the specified [`root`](#root) file system bundle have been compiled.
-  The runtime MUST generate an error if it does not support the specified **`arch`**.
-  Values for **`arch`** SHOULD use, and runtimes SHOULD understand, **`arch`** entries listed in the Go Language document for [`GOARCH`][go-environment].
-  If an architecture is not included in the `GOARCH` documentation, it SHOULD be submitted to this specification for standardization.
+**`platform`** (string, REQUIRED) specifies the configuration's target platform.
+  The value MUST be a slug from [the platform list](spec.md#platforms).
 
 ### Example
 
 ```json
-"platform": {
-    "os": "linux",
-    "arch": "amd64"
-}
+"platform": "linux"
 ```
 
 ## <a name="configPlatformSpecificConfiguration" />Platform-specific configuration
 
-[**`platform.os`**](#platform) is used to specify platform-specific configuration.
+[**`platform`**](#platform) is used to specify platform-specific configuration.
 Runtime implementations MAY support any valid values for platform-specific fields as part of this configuration.
 
 * **`linux`** (object, OPTIONAL) [Linux-specific configuration](config-linux.md).
-  This MAY be set if **`platform.os`** is `linux` and MUST NOT be set otherwise.
+  This MAY be set if **`platform`** is `linux` and MUST NOT be set otherwise.
 * **`windows`** (object, OPTIONAL) [Windows-specific configuration](config-windows.md).
-  This MAY be set if **`platform.os`** is `windows` and MUST NOT be set otherwise.
+  This MAY be set if **`platform`** is `windows` and MUST NOT be set otherwise.
 * **`solaris`** (object, OPTIONAL) [Solaris-specific configuration](config-solaris.md).
-  This MAY be set if **`platform.os`** is `solaris` and MUST NOT be set otherwise.
+  This MAY be set if **`platform`** is `solaris` and MUST NOT be set otherwise.
 
 ### Example (Linux)
 
 ```json
 {
-    "platform": {
-        "os": "linux",
-        "arch": "amd64"
-    },
+    "platform": "linux",
     "linux": {
         "namespaces": [
           {
@@ -459,10 +445,7 @@ Here is a full example `config.json` for reference.
 ```json
 {
     "ociVersion": "0.5.0-dev",
-    "platform": {
-        "os": "linux",
-        "arch": "amd64"
-    },
+    "platform": "linux",
     "process": {
         "terminal": true,
         "user": {

schema/config-schema.json

@@ -39,21 +39,7 @@
         },
         "platform": {
             "id": "https://opencontainers.org/schema/bundle/platform",
-            "type": "object",
-            "required": [
-                "arch",
-                "os"
-            ],
-            "properties": {
-                "arch": {
-                    "id": "https://opencontainers.org/schema/bundle/platform/arch",
-                    "type": "string"
-                },
-                "os": {
-                    "id": "https://opencontainers.org/schema/bundle/platform/os",
-                    "type": "string"
-                }
-            }
+            "type": "string"
         },
         "root": {
             "description": "Configures the container's root filesystem.",

schema/test/config/good/minimal-for-start.json

@@ -1,9 +1,6 @@
 {
     "ociVersion": "1.0.0",
-    "platform": {
-        "os": "linux",
-        "arch": "amd64"
-    },
+    "platform": "linux",
     "root": {
         "path": "rootfs"
     },

schema/test/config/good/minimal.json

@@ -1,9 +1,6 @@
 {
     "ociVersion": "1.0.0",
-    "platform": {
-        "os": "linux",
-        "arch": "amd64"
-    },
+    "platform": "linux",
     "root": {
         "path": "rootfs"
     }

schema/test/config/good/spec-example.json

@@ -1,9 +1,6 @@
 {
     "ociVersion": "0.5.0-dev",
-    "platform": {
-        "os": "linux",
-        "arch": "amd64"
-    },
+    "platform": "linux",
     "process": {
         "terminal": true,
         "user": {

specs-go/config.go

@@ -7,7 +7,7 @@ type Spec struct {
 	// Version of the Open Container Runtime Specification with which the bundle complies.
 	Version string `json:"ociVersion"`
 	// Platform specifies the configuration's target platform.
-	Platform Platform `json:"platform"`
+	Platform string `json:"platform"`
 	// Process configures the container process.
 	Process *Process `json:"process,omitempty"`
 	// Root configures the container's root filesystem.
@@ -101,15 +101,6 @@ type Root struct {
 	Readonly bool `json:"readonly,omitempty"`
 }
 
-// Platform specifies OS and arch information for the host system that the container
-// is created for.
-type Platform struct {
-	// OS is the operating system.
-	OS string `json:"os"`
-	// Arch is the architecture
-	Arch string `json:"arch"`
-}
-
 // Mount specifies a mount for a container.
 type Mount struct {
 	// Destination is the path where the mount will be placed relative to the container's root.  The path and child directories MUST exist, a runtime MUST NOT create directories automatically to a mount point.