Add initial container implementation.

Signed-off-by: Lantao Liu <lantaol@google.com>

pkg/server/events.go

@@ -0,0 +1,94 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package server
+
+import (
+	"github.com/golang/glog"
+	"golang.org/x/net/context"
+
+	"github.com/containerd/containerd/api/services/execution"
+	"github.com/containerd/containerd/api/types/container"
+
+	"github.com/kubernetes-incubator/cri-containerd/pkg/metadata"
+)
+
+// startEventMonitor starts an event monitor which monitors and handles all
+// container events.
+func (c *criContainerdService) startEventMonitor() error {
+	events, err := c.containerService.Events(context.Background(), &execution.EventsRequest{})
+	if err != nil {
+		return err
+	}
+	go func() {
+		for {
+			c.handleEvent(events)
+		}
+	}()
+	return nil
+}
+
+// handleEvent receives an event from contaienrd and handles the event.
+func (c *criContainerdService) handleEvent(events execution.ContainerService_EventsClient) {
+	e, err := events.Recv()
+	if err != nil {
+		glog.Errorf("Failed to receive event: %v", err)
+		return
+	}
+	glog.V(2).Infof("Received container event: %+v", e)
+	switch e.Type {
+	// If containerd-shim exits unexpectedly, there will be no corresponding event.
+	// However, containerd could not retrieve container state in that case, so it's
+	// fine to leave out that case for now.
+	// TODO(random-liu): [P2] Handle container-shim exit.
+	case container.Event_EXIT:
+		meta, err := c.containerStore.Get(e.ID)
+		if err != nil {
+			glog.Errorf("Failed to get container %q metadata: %v", e.ID, err)
+			return
+		}
+		if e.Pid != meta.Pid {
+			// Not init process dies, ignore the event.
+			return
+		}
+		// Delete the container from containerd.
+		_, err = c.containerService.Delete(context.Background(), &execution.DeleteRequest{ID: e.ID})
+		if err != nil && !isContainerdContainerNotExistError(err) {
+			// TODO(random-liu): [P0] Enqueue the event and retry.
+			glog.Errorf("Failed to delete container %q: %v", e.ID, err)
+			return
+		}
+		err = c.containerStore.Update(e.ID, func(meta metadata.ContainerMetadata) (metadata.ContainerMetadata, error) {
+			// If FinishedAt has been set (e.g. with start failure), keep as
+			// it is.
+			if meta.FinishedAt != 0 {
+				return meta, nil
+			}
+			meta.Pid = 0
+			meta.FinishedAt = e.ExitedAt.UnixNano()
+			meta.ExitCode = int32(e.ExitStatus)
+			return meta, nil
+		})
+		if err != nil {
+			glog.Errorf("Failed to update container %q state: %v", e.ID, err)
+			// TODO(random-liu): [P0] Enqueue the event and retry.
+			return
+		}
+	case container.Event_OOM:
+		// TODO(random-liu): [P1] Handle OOM event.
+	}
+	return
+}