Deprecate legacy shims

Fix #4365

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

services/tasks/local.go

@@ -184,6 +184,11 @@ func (l *local) Create(ctx context.Context, r *api.CreateTaskRequest, _ ...grpc.
 			Options: m.Options,
 		})
 	}
+	if strings.HasPrefix(container.Runtime.Name, "io.containerd.runtime.v1.") {
+		log.G(ctx).Warn("runtime v1 is deprecated since containerd v1.4, consider using runtime v2")
+	} else if container.Runtime.Name == plugin.RuntimeRuncV1 {
+		log.G(ctx).Warnf("%q is deprecated since containerd v1.4, consider using %q", plugin.RuntimeRuncV1, plugin.RuntimeRuncV2)
+	}
 	rtime, err := l.getRuntime(container.Runtime.Name)
 	if err != nil {
 		return nil, err