Add Cgroups to runtime config

This will create the list of cgroups specified

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

docs/yaml.md

@@ -183,6 +183,7 @@ permissions issues in use.
 
 In addition to the parts of the specification above used to generate the OCI spec, there is a `runtime` section in the image specification
 which specifies some actions to take place when the container is being started.
+- `cgroups` takes a list of cgroups that will be created before the container is run.
 - `mounts` takes a list of mount specifications (`source`, `destination`, `type`, `options`) and mounts them in the root namespace before the container is created. It will
   try to make any missing destination directories.
 - `mkdir` takes a list of directories to create at runtime, in the root mount namespace. These are created before the container is started, so they can be used to create

src/moby/config.go

@@ -100,6 +100,7 @@ type Image struct {
 
 // Runtime is the type of config processed at runtime, not used to build the OCI spec
 type Runtime struct {
+	Cgroups    *[]string      `yaml:"cgroups" json:"cgroups,omitempty"`
 	Mounts     *[]specs.Mount `yaml:"mounts" json:"mounts,omitempty"`
 	Mkdir      *[]string      `yaml:"mkdir" json:"mkdir,omitempty"`
 	Interfaces *[]Interface   `yaml:"interfaces" json:"interfaces,omitempty"`
@@ -570,10 +571,12 @@ func assignRuntime(v1, v2 *Runtime) Runtime {
 	if v2 == nil {
 		v2 = &Runtime{}
 	}
+	runtimeCgroups := assignStrings(v1.Cgroups, v2.Cgroups)
 	runtimeMounts := assignBinds(v1.Mounts, v2.Mounts)
 	runtimeMkdir := assignStrings(v1.Mkdir, v2.Mkdir)
 	runtimeInterfaces := assignRuntimeInterfaceArray(v1.Interfaces, v2.Interfaces)
 	runtime := Runtime{
+		Cgroups:    &runtimeCgroups,
 		Mounts:     &runtimeMounts,
 		Mkdir:      &runtimeMkdir,
 		Interfaces: &runtimeInterfaces,

src/moby/schema.go

@@ -239,6 +239,7 @@ var schema = string(`
       "type": "object",
       "additionalProperties": false,
       "properties": {
+        "cgroups": {"$ref": "#/definitions/strings"},
         "mounts": {"$ref": "#/definitions/mounts"},
         "mkdir": {"$ref": "#/definitions/strings"},
         "interfaces": {"$ref": "#/definitions/interfaces"},