Annotations: Provide container metadata for VM based runtimes

For hypervisor-based container runtimes (like Kata Containers, Clear Containers
or runv) a pod will be created in a VM and then create containers within the VM.

When a runtime is requested for container commands like create and start, both
the instal "pause" container and next containers need to be added to the pod
namespace (same VM).

A runtime does not know if it needs to create/start a VM or if it needs to add a
container to an already running VM pod.

This patch adds a way to provide this information through container annotations.
When starting a container or a sandbox, 2 annotations are added:

- type (Container or Sandbox)
- sandbox name

This allow to a VM based runtime to decide if they need to create a pod VM or
container within the VM pod.

Signed-off-by: Jose Carlos Venegas Munoz <jose.carlos.venegas.munoz@intel.com>

pkg/server/sandbox_run.go

@@ -34,6 +34,7 @@ import (
 	"golang.org/x/sys/unix"
 	"k8s.io/kubernetes/pkg/kubelet/apis/cri/v1alpha1/runtime"
 
+	"github.com/containerd/cri-containerd/pkg/annotations"
 	customopts "github.com/containerd/cri-containerd/pkg/containerd/opts"
 	sandboxstore "github.com/containerd/cri-containerd/pkg/store/sandbox"
 	"github.com/containerd/cri-containerd/pkg/util"
@@ -331,6 +332,9 @@ func (c *criContainerdService) generateSandboxContainerSpec(id string, config *r
 	g.SetLinuxResourcesCPUShares(uint64(defaultSandboxCPUshares))
 	g.SetProcessOOMScoreAdj(int(defaultSandboxOOMAdj))
 
+	g.AddAnnotation(annotations.ContainerType, annotations.ContainerTypeSandbox)
+	g.AddAnnotation(annotations.SandboxID, id)
+
 	return g.Spec(), nil
 }