kubelet: wire checkpoint container support through

This adds the last pieces to wire through the container checkpoint
support in the kubelet.

Signed-off-by: Adrian Reber <areber@redhat.com>

pkg/kubelet/server/server.go

@@ -62,6 +62,7 @@ import (
 	"k8s.io/component-base/logs"
 	compbasemetrics "k8s.io/component-base/metrics"
 	"k8s.io/component-base/metrics/legacyregistry"
+	runtimeapi "k8s.io/cri-api/pkg/apis/runtime/v1"
 	podresourcesapi "k8s.io/kubelet/pkg/apis/podresources/v1"
 	podresourcesapiv1alpha1 "k8s.io/kubelet/pkg/apis/podresources/v1alpha1"
 	"k8s.io/kubernetes/pkg/api/legacyscheme"
@@ -224,6 +225,7 @@ type HostInterface interface {
 	GetCachedMachineInfo() (*cadvisorapi.MachineInfo, error)
 	GetRunningPods() ([]*v1.Pod, error)
 	RunInContainer(name string, uid types.UID, container string, cmd []string) ([]byte, error)
+	CheckpointContainer(podUID types.UID, podFullName, containerName string, options *runtimeapi.CheckpointContainerRequest) error
 	GetKubeletContainerLogs(ctx context.Context, podFullName, containerName string, logOptions *v1.PodLogOptions, stdout, stderr io.Writer) error
 	ServeLogs(w http.ResponseWriter, req *http.Request)
 	ResyncInterval() time.Duration
@@ -403,6 +405,17 @@ func (s *Server) InstallDefaultHandlers() {
 	s.restfulCont.Handle(proberMetricsPath,
 		compbasemetrics.HandlerFor(p, compbasemetrics.HandlerOpts{ErrorHandling: compbasemetrics.ContinueOnError}),
 	)
+
+	// Only enable checkpoint API if the feature is enabled
+	if utilfeature.DefaultFeatureGate.Enabled(features.ContainerCheckpoint) {
+		s.addMetricsBucketMatcher("checkpoint")
+		ws = &restful.WebService{}
+		ws.Path("/checkpoint").Produces(restful.MIME_JSON)
+		ws.Route(ws.POST("/{podNamespace}/{podID}/{containerName}").
+			To(s.checkpoint).
+			Operation("checkpoint"))
+		s.restfulCont.Add(ws)
+	}
 }
 
 // InstallDebuggingHandlers registers the HTTP request patterns that serve logs or run commands/containers
@@ -878,6 +891,83 @@ func (s *Server) getPortForward(request *restful.Request, response *restful.Resp
 	proxyStream(response.ResponseWriter, request.Request, url)
 }
 
+// checkpoint handles the checkpoint API request. It checks if the requested
+// podNamespace, pod and container actually exist and only then calls out
+// to the runtime to actually checkpoint the container.
+func (s *Server) checkpoint(request *restful.Request, response *restful.Response) {
+	pod, ok := s.host.GetPodByName(request.PathParameter("podNamespace"), request.PathParameter("podID"))
+	if !ok {
+		response.WriteError(http.StatusNotFound, fmt.Errorf("pod does not exist"))
+		return
+	}
+
+	containerName := request.PathParameter("containerName")
+
+	found := false
+	for _, container := range pod.Spec.Containers {
+		if container.Name == containerName {
+			found = true
+		}
+	}
+	if !found {
+		for _, container := range pod.Spec.InitContainers {
+			if container.Name == containerName {
+				found = true
+			}
+		}
+	}
+	if !found && utilfeature.DefaultFeatureGate.Enabled(features.EphemeralContainers) {
+		for _, container := range pod.Spec.EphemeralContainers {
+			if container.Name == containerName {
+				found = true
+			}
+		}
+	}
+	if !found {
+		response.WriteError(
+			http.StatusNotFound,
+			fmt.Errorf("container %v does not exist", containerName),
+		)
+		return
+	}
+
+	options := &runtimeapi.CheckpointContainerRequest{}
+	// Query parameter to select an optional timeout. Without the timeout parameter
+	// the checkpoint command will use the default CRI timeout.
+	timeouts := request.Request.URL.Query()["timeout"]
+	if len(timeouts) > 0 {
+		// If the user specified one or multiple values for timeouts we
+		// are using the last available value.
+		timeout, err := strconv.ParseInt(timeouts[len(timeouts)-1], 10, 64)
+		if err != nil {
+			response.WriteError(
+				http.StatusNotFound,
+				fmt.Errorf("cannot parse value of timeout parameter"),
+			)
+			return
+		}
+		options.Timeout = timeout
+	}
+
+	if err := s.host.CheckpointContainer(pod.UID, kubecontainer.GetPodFullName(pod), containerName, options); err != nil {
+		response.WriteError(
+			http.StatusInternalServerError,
+			fmt.Errorf(
+				"checkpointing of %v/%v/%v failed (%v)",
+				request.PathParameter("podNamespace"),
+				request.PathParameter("podID"),
+				containerName,
+				err,
+			),
+		)
+		return
+	}
+	writeJSONResponse(
+		response,
+		[]byte(fmt.Sprintf("{\"items\":[\"%s\"]}", options.Location)),
+	)
+}
+
 // getURLRootPath trims a URL path.
 // For paths in the format of "/metrics/xxx", "metrics/xxx" is returned;
 // For all other paths, the first part of the path is returned.