Add HostNetworking container option to API.

This allows a container to run within the same networking namespace as
the host. This will be locked down by default using a flag on the master
and nodes (similar to how privileged is handled today).

pkg/api/types.go

@@ -288,6 +288,7 @@ type ContainerPort struct {
 	// in a pod must have a unique name.
 	Name string `json:"name,omitempty"`
 	// Optional: If specified, this must be a valid port number, 0 < x < 65536.
+	// If HostNetwork is specified, this must match ContainerPort.
 	HostPort int `json:"hostPort,omitempty"`
 	// Required: This must be a valid port number, 0 < x < 65536.
 	ContainerPort int `json:"containerPort"`
@@ -587,6 +588,10 @@ type PodSpec struct {
 	// the the scheduler simply schedules this pod onto that host, assuming that it fits
 	// resource requirements.
 	Host string `json:"host,omitempty"`
+	// Uses the host's network namespace. If this option is set, the ports that will be
+	// used must be specified.
+	// Optional: Default to false.
+	HostNetwork bool `json:"hostNetwork,omitempty"`
 }
 
 // PodStatus represents information about the status of a pod. Status may trail the actual