Add SwapStats to summary API through cadvisor

Signed-off-by: Itamar Holder <iholder@redhat.com>

pkg/kubelet/stats/cadvisor_stats_provider.go

@@ -152,6 +152,7 @@ func (p *cadvisorStatsProvider) ListPodStats(_ context.Context) ([]statsapi.PodS
 			cpu, memory := cadvisorInfoToCPUandMemoryStats(podInfo)
 			podStats.CPU = cpu
 			podStats.Memory = memory
+			podStats.Swap = cadvisorInfoToSwapStats(podInfo)
 			podStats.ProcessStats = cadvisorInfoToProcessStats(podInfo)
 		}
 
@@ -227,6 +228,7 @@ func (p *cadvisorStatsProvider) ListPodCPUAndMemoryStats(_ context.Context) ([]s
 			cpu, memory := cadvisorInfoToCPUandMemoryStats(podInfo)
 			podStats.CPU = cpu
 			podStats.Memory = memory
+			podStats.Swap = cadvisorInfoToSwapStats(podInfo)
 		}
 		result = append(result, *podStats)
 	}

pkg/kubelet/stats/helper.go

@@ -95,6 +95,7 @@ func cadvisorInfoToContainerStats(name string, info *cadvisorapiv2.ContainerInfo
 	cpu, memory := cadvisorInfoToCPUandMemoryStats(info)
 	result.CPU = cpu
 	result.Memory = memory
+	result.Swap = cadvisorInfoToSwapStats(info)
 
 	// NOTE: if they can be found, log stats will be overwritten
 	// by the caller, as it knows more information about the pod,
@@ -257,6 +258,29 @@ func cadvisorInfoToUserDefinedMetrics(info *cadvisorapiv2.ContainerInfo) []stats
 	return udm
 }
 
+func cadvisorInfoToSwapStats(info *cadvisorapiv2.ContainerInfo) *statsapi.SwapStats {
+	cstat, found := latestContainerStats(info)
+	if !found {
+		return nil
+	}
+
+	var swapStats *statsapi.SwapStats
+
+	if info.Spec.HasMemory && cstat.Memory != nil {
+		swapStats = &statsapi.SwapStats{
+			Time:           metav1.NewTime(cstat.Timestamp),
+			SwapUsageBytes: &cstat.Memory.Swap,
+		}
+
+		if !isMemoryUnlimited(info.Spec.Memory.SwapLimit) {
+			swapAvailableBytes := info.Spec.Memory.SwapLimit - cstat.Memory.Swap
+			swapStats.SwapAvailableBytes = &swapAvailableBytes
+		}
+	}
+
+	return swapStats
+}
+
 // latestContainerStats returns the latest container stats from cadvisor, or nil if none exist
 func latestContainerStats(info *cadvisorapiv2.ContainerInfo) (*cadvisorapiv2.ContainerStats, bool) {
 	stats := info.Stats