Rework hostfs metrics

Ephemeral storage usage should be calculated by the metrics code,
not the eviction code.

pkg/kubelet/stats/host_stats_provider.go

@@ -0,0 +1,155 @@
+/*
+Copyright 2018 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 stats
+
+import (
+	"fmt"
+	"path/filepath"
+
+	cadvisorapiv2 "github.com/google/cadvisor/info/v2"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/types"
+	statsapi "k8s.io/kubelet/pkg/apis/stats/v1alpha1"
+	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
+	"k8s.io/kubernetes/pkg/kubelet/kuberuntime"
+	"k8s.io/kubernetes/pkg/volume"
+)
+
+// PodEtcHostsFunc is a function to fetch a etc hosts path by pod uid.
+type PodEtcHostsPathFunc func(podUID types.UID) string
+
+// metricsProviderByPath maps a path to its metrics provider
+type metricsProviderByPath map[string]volume.MetricsProvider
+
+// HostStatsProvider defines an interface for providing host stats associated with pod.
+type HostStatsProvider interface {
+	// getPodLogStats gets stats associated with pod log usage
+	getPodLogStats(podNamespace, podName string, podUID types.UID, rootFsInfo *cadvisorapiv2.FsInfo) (*statsapi.FsStats, error)
+	// getPodContainerLogStats gets stats associated with container log usage
+	getPodContainerLogStats(podNamespace, podName string, podUID types.UID, containerName string, rootFsInfo *cadvisorapiv2.FsInfo) (*statsapi.FsStats, error)
+	// getPodEtcHostsStats gets stats associated with pod etc-hosts usage
+	getPodEtcHostsStats(podUID types.UID, rootFsInfo *cadvisorapiv2.FsInfo) (*statsapi.FsStats, error)
+}
+
+type hostStatsProvider struct {
+	// osInterface is the interface for syscalls.
+	osInterface kubecontainer.OSInterface
+	// podEtcHostsPathFunc fetches a pod etc hosts path by uid.
+	podEtcHostsPathFunc PodEtcHostsPathFunc
+}
+
+// NewLogMetricsService returns a new LogMetricsService type struct.
+func NewHostStatsProvider(osInterface kubecontainer.OSInterface, podEtcHostsPathFunc PodEtcHostsPathFunc) HostStatsProvider {
+	return hostStatsProvider{
+		osInterface:         osInterface,
+		podEtcHostsPathFunc: podEtcHostsPathFunc,
+	}
+}
+
+func (h hostStatsProvider) getPodLogStats(podNamespace, podName string, podUID types.UID, rootFsInfo *cadvisorapiv2.FsInfo) (*statsapi.FsStats, error) {
+	metricsByPath, err := h.podLogMetrics(podNamespace, podName, podUID)
+	if err != nil {
+		return nil, err
+	}
+	return metricsByPathToFsStats(metricsByPath, rootFsInfo)
+}
+
+// getPodContainerLogStats gets stats for container
+func (h hostStatsProvider) getPodContainerLogStats(podNamespace, podName string, podUID types.UID, containerName string, rootFsInfo *cadvisorapiv2.FsInfo) (*statsapi.FsStats, error) {
+	metricsByPath, err := h.podContainerLogMetrics(podNamespace, podName, podUID, containerName)
+	if err != nil {
+		return nil, err
+	}
+	return metricsByPathToFsStats(metricsByPath, rootFsInfo)
+}
+
+// getPodEtcHostsStats gets status for pod etc hosts usage
+func (h hostStatsProvider) getPodEtcHostsStats(podUID types.UID, rootFsInfo *cadvisorapiv2.FsInfo) (*statsapi.FsStats, error) {
+	metrics := h.podEtcHostsMetrics(podUID)
+	hostMetrics, err := metrics.GetMetrics()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get stats %v", err)
+	}
+	result := rootFsInfoToFsStats(rootFsInfo)
+	usedBytes := uint64(hostMetrics.Used.Value())
+	inodesUsed := uint64(hostMetrics.InodesUsed.Value())
+	result.UsedBytes = addUsage(result.UsedBytes, &usedBytes)
+	result.InodesUsed = addUsage(result.InodesUsed, &inodesUsed)
+	result.Time = maxUpdateTime(&result.Time, &hostMetrics.Time)
+	return result, nil
+}
+
+func (h hostStatsProvider) podLogMetrics(podNamespace, podName string, podUID types.UID) (metricsProviderByPath, error) {
+	podLogsDirectoryPath := kuberuntime.BuildPodLogsDirectory(podNamespace, podName, podUID)
+	return h.fileMetricsByDir(podLogsDirectoryPath)
+}
+
+func (h hostStatsProvider) podContainerLogMetrics(podNamespace, podName string, podUID types.UID, containerName string) (metricsProviderByPath, error) {
+	podContainerLogsDirectoryPath := kuberuntime.BuildContainerLogsDirectory(podNamespace, podName, podUID, containerName)
+	return h.fileMetricsByDir(podContainerLogsDirectoryPath)
+}
+
+func (h hostStatsProvider) podEtcHostsMetrics(podUID types.UID) volume.MetricsProvider {
+	podEtcHostsPath := h.podEtcHostsPathFunc(podUID)
+	return volume.NewMetricsDu(podEtcHostsPath)
+}
+
+// fileMetricsByDir returns metrics by path for each file under specified directory
+func (h hostStatsProvider) fileMetricsByDir(dirname string) (metricsProviderByPath, error) {
+	files, err := h.osInterface.ReadDir(dirname)
+	if err != nil {
+		return nil, err
+	}
+	results := metricsProviderByPath{}
+	for _, f := range files {
+		if f.IsDir() {
+			continue
+		}
+		// Only include *files* under pod log directory.
+		fpath := filepath.Join(dirname, f.Name())
+		results[fpath] = volume.NewMetricsDu(fpath)
+	}
+	return results, nil
+}
+
+// metricsByPathToFsStats converts a metrics provider by path to fs stats
+func metricsByPathToFsStats(metricsByPath metricsProviderByPath, rootFsInfo *cadvisorapiv2.FsInfo) (*statsapi.FsStats, error) {
+	result := rootFsInfoToFsStats(rootFsInfo)
+	for fpath, metrics := range metricsByPath {
+		hostMetrics, err := metrics.GetMetrics()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get fsstats for %q: %v", fpath, err)
+		}
+		usedBytes := uint64(hostMetrics.Used.Value())
+		inodesUsed := uint64(hostMetrics.InodesUsed.Value())
+		result.UsedBytes = addUsage(result.UsedBytes, &usedBytes)
+		result.InodesUsed = addUsage(result.InodesUsed, &inodesUsed)
+		result.Time = maxUpdateTime(&result.Time, &hostMetrics.Time)
+	}
+	return result, nil
+}
+
+// rootFsInfoToFsStats is a utility to convert rootFsInfo into statsapi.FsStats
+func rootFsInfoToFsStats(rootFsInfo *cadvisorapiv2.FsInfo) *statsapi.FsStats {
+	return &statsapi.FsStats{
+		Time:           metav1.NewTime(rootFsInfo.Timestamp),
+		AvailableBytes: &rootFsInfo.Available,
+		CapacityBytes:  &rootFsInfo.Capacity,
+		InodesFree:     rootFsInfo.InodesFree,
+		Inodes:         rootFsInfo.Inodes,
+	}
+}