Add methods for listing and fetching container stats

This uses the previously unusued lib/stats.go code to return data
about container stats to the CRI API.

As a shortcut for intial testing, I've made ListContainerStats an API
composition of the ContainerStats and ListContainers APIs
directly (calls the same server methods with the same context), but
this should be refactored into an internal API.

No data on filesystem layer usage is returned at this time.

Fixes one-half of #1248

Signed-off-by: Yann Ramin <atrus@stackworks.net>

lib/stats.go

@@ -15,8 +15,8 @@ import (
 type ContainerStats struct {
 	Container   string
 	CPU         float64
-	cpuNano     uint64
-	systemNano  uint64
+	CPUNano     uint64
+	SystemNano  uint64
 	MemUsage    uint64
 	MemLimit    uint64
 	MemPerc     float64
@@ -29,8 +29,8 @@ type ContainerStats struct {
 
 // GetContainerStats gets the running stats for a given container
 func (c *ContainerServer) GetContainerStats(ctr *oci.Container, previousStats *ContainerStats) (*ContainerStats, error) {
-	previousCPU := previousStats.cpuNano
-	previousSystem := previousStats.systemNano
+	previousCPU := previousStats.CPUNano
+	previousSystem := previousStats.SystemNano
 	libcontainerStats, err := c.LibcontainerStats(ctr)
 	if err != nil {
 		return nil, err

server/container_stats.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"time"
 
+	"github.com/kubernetes-incubator/cri-o/lib"
 	"golang.org/x/net/context"
 	pb "k8s.io/kubernetes/pkg/kubelet/apis/cri/v1alpha1/runtime"
 )
@@ -16,5 +17,35 @@ func (s *Server) ContainerStats(ctx context.Context, req *pb.ContainerStatsReque
 		recordOperation(operation, time.Now())
 		recordError(operation, err)
 	}()
-	return nil, fmt.Errorf("not implemented")
+
+	container := s.GetContainer(req.ContainerId)
+	if container == nil {
+		return nil, fmt.Errorf("invalid container")
+	}
+
+	now := time.Now().UnixNano()
+	stats, err := s.GetContainerStats(container, &lib.ContainerStats{})
+	if err != nil {
+		return nil, err
+	}
+
+	return &pb.ContainerStatsResponse{
+		&pb.ContainerStats{
+			Attributes: &pb.ContainerAttributes{
+				Id:          req.ContainerId,
+				Metadata:    container.Metadata(),
+				Labels:      container.Labels(),
+				Annotations: container.Annotations(),
+			},
+			Cpu: &pb.CpuUsage{
+				Timestamp:            now,
+				UsageCoreNanoSeconds: &pb.UInt64Value{stats.CPUNano + stats.SystemNano},
+			},
+			Memory: &pb.MemoryUsage{
+				Timestamp:       now,
+				WorkingSetBytes: &pb.UInt64Value{stats.MemUsage},
+			},
+			WritableLayer: nil,
+		},
+	}, nil
 }

server/container_stats_list.go

@@ -1,9 +1,9 @@
 package server
 
 import (
-	"fmt"
 	"time"
 
+	"github.com/sirupsen/logrus"
 	"golang.org/x/net/context"
 	pb "k8s.io/kubernetes/pkg/kubelet/apis/cri/v1alpha1/runtime"
 )
@@ -15,5 +15,32 @@ func (s *Server) ListContainerStats(ctx context.Context, req *pb.ListContainerSt
 		recordOperation(operation, time.Now())
 		recordError(operation, err)
 	}()
-	return nil, fmt.Errorf("not implemented")
+
+	// This is an inefficient method, since the container will be resolved twice,
+	// once by the container list code and once by the GetContainerStats call.
+	containers, err := s.ListContainers(ctx, &pb.ListContainersRequest{
+		&pb.ContainerFilter{
+			Id:            req.Filter.Id,
+			PodSandboxId:  req.Filter.PodSandboxId,
+			LabelSelector: req.Filter.LabelSelector,
+		},
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	var allStats []*pb.ContainerStats
+
+	for _, container := range containers.Containers {
+		stats, err := s.ContainerStats(ctx, &pb.ContainerStatsRequest{ContainerId: container.Id})
+		if err != nil {
+			logrus.Warn("unable to get stats for container %s", container.Id)
+			continue
+		}
+		allStats = append(allStats, stats.Stats)
+	}
+
+	return &pb.ListContainerStatsResponse{
+		Stats: allStats,
+	}, nil
 }