##cAdvisor监控数据分析
入口
- 代码入口：
github.com/google/cadvisor/cadvisor.go - API handler:
github.com/google/cadvisor/api/handler.go - 基于 tag： v0.19.2
# github.com/google/cadvisor/cadvisor.go
... ...
73 containerManager, err := manager.New(memoryStorage, sysFs, *maxHousekeepingInterval, *allowDynamicHousekeeping)
74 if err != nil {
75 glog.Fatalf("Failed to create a Container Manager: %s", err)
76 }
77
78 mux := http.DefaultServeMux
79
80 // Register all HTTP handlers.
81 err = cadvisorHttp.RegisterHandlers(mux, containerManager, *httpAuthFile, *httpAuthRealm, *httpDigestFile, *httpDigestRealm)
82 if err != nil {
83 glog.Fatalf("Failed to register HTTP handlers: %v", err)
84 }
85
86 cadvisorHttp.RegisterPrometheusHandler(mux, containerManager, *prometheusEndpoint, nil)
87
88 // Start the manager.
89 if err := containerManager.Start(); err != nil {
90 glog.Fatalf("Failed to start container manager: %v", err)
91 }
... ...
从入口可以得知真正获取 container 和 machine 信息的 interface 为 Manager，github.com/google/cadvisor/manager/manager.go
# github.com/google/cadvisor/manager/manager.go
52 // The Manager interface defines operations for starting a manager and getting
53 // container and machine information.
54 type Manager interface {
55 // Start the manager. Calling other manager methods before this returns
56 // may produce undefined behavior.
57 Start() error
58
59 // Stops the manager.
60 Stop() error
61
62 // Get information about a container.
63 GetContainerInfo(containerName string, query *info.ContainerInfoRequest) (*info.ContainerInfo, error)
... ...
以下对 cadvisor 具体如何获取到 machine 和 docker container 的信息结合代码具体讲解。
Machine Info
# github.com/google/cadvisor/manager/manager.go
158 machineInfo, err := getMachineInfo(sysfs, fsInfo) // 此处通过 getMachineInfo() 函数获取 machine 信息
159 if err != nil {
160 return nil, err
161 }
162 newManager.machineInfo = *machineInfo
163 glog.Infof("Machine: %+v", newManager.machineInfo)
获取 machineinfo 的具体函数 getMachineInfo()
# github.com/google/cadvisor/manager/machine.go
52 func getMachineInfo(sysFs sysfs.SysFs, fsInfo fs.FsInfo) (*info.MachineInfo, error) {
53 cpuinfo, err := ioutil.ReadFile("/proc/cpuinfo")
54 clockSpeed, err := machine.GetClockSpeed(cpuinfo)
55 if err != nil {
56 return nil, err
57 }
58
... ...
MachineInfo 数据结构：
# github.com/google/cadvisor/info/v1/machine.go
131 type MachineInfo struct {
132 // The number of cores in this machine.
133 NumCores int `json:"num_cores"`
134
135 // Maximum clock speed for the cores, in KHz.
136 CpuFrequency uint64 `json:"cpu_frequency_khz"`
137
138 // The amount of memory (in bytes) in this machine
139 MemoryCapacity int64 `json:"memory_capacity"`
140
141 // The machine id
142 MachineID string `json:"machine_id"`
143
144 // The system uuid
145 SystemUUID string `json:"system_uuid"`
146
147 // The boot id
148 BootID string `json:"boot_id"`
149
150 // Filesystems on this machine.
151 Filesystems []FsInfo `json:"filesystems"`
152
153 // Disk map
154 DiskMap map[string]DiskInfo `json:"disk_map"`
155
156 // Network devices
157 NetworkDevices []NetInfo `json:"network_devices"`
158
159 // Machine Topology
160 // Describes cpu/memory layout and hierarchy.
161 Topology []Node `json:"topology"`
162
163 // Cloud provider the machine belongs to.
164 CloudProvider CloudProvider `json:"cloud_provider"`
165
166 // Type of cloud instance (e.g. GCE standard) the machine is.
167 InstanceType InstanceType `json:"instance_type"`
168 }
- cpu
/proc/cpuinfo - mem
/proc/meminfo
# github.com/google/cadvisor/utils/machine/machine.go
76 func GetMachineMemoryCapacity() (int64, error) {
77 out, err := ioutil.ReadFile("/proc/meminfo")
78 if err != nil {
79 return 0, err
80 }
81
82 memoryCapacity, err := parseCapacity(out, memoryCapacityRegexp)
83 if err != nil {
84 return 0, err
85 }
86 return memoryCapacity, err
87 }
- machine_id
/var/lib/dbus/machine-id - boot_id
/proc/sys/kernel/random/boot_id
➜ ~ cat /var/lib/dbus/machine-id
a8919ec7c9ee43bd1bcaf6cd55e1a7bc
➜ ~ cat /proc/sys/kernel/random/boot_id
2f6bac7f-738a-4d85-8b58-53e71296119e
- disk
/proc/diskstats
# github.com/google/cadvisor/fs/fs.go
189 func (self *RealFsInfo) GetFsInfoForPath(mountSet map[string]struct{}) ([]Fs, error) {
190 filesystems := make([]Fs, 0)
191 deviceSet := make(map[string]struct{})
192 diskStatsMap, err := getDiskStatsMap("/proc/diskstats") // 磁盘状态通过 /proc/diskstats 获取
193 if err != nil {
194 return nil, err
195 }
... ...
对于分配给容器的 pool 值，如果是 device mapper 类型的，则通过 dmsetup status pool_device_name 获取设备使用情况
# github.com/google/cadvisor/fs/fs.go
... ...
205 case "devicemapper":
206 total, free, avail, err = getDMStats(device, partition.blockSize)
....
- 获取磁盘设备信息
/sys/block
# github.com/google/cadvisor/utils/sysinfo/sysinfo.go
31 func GetBlockDeviceInfo(sysfs sysfs.SysFs) (map[string]info.DiskInfo, error) {
32 disks, err := sysfs.GetBlockDevices()
// cadvisor/utils/sysfs/sysfs.go GetBlockDevices() 可知，通过 /sys/block 获取磁盘设备名，其它信息雷同
33 if err != nil {
34 return nil, err
35 }
... ...
➜ ~ cat /sys/block/sda/dev # 主次设备号
8:0
➜ ~ cat /sys/block/sda/size # 磁盘设备大小
976773168
➜ ~ cat /sys/block/sda/queue/scheduler # 磁盘调度类型
noop deadline [cfq]
➜ ~
- netDevices
/sys/class/net
# github.com/google/cadvisor/utils/sysinfo/sysinfo.go
87 func GetNetworkDevices(sysfs sysfs.SysFs) ([]info.NetInfo, error) {
88 devs, err := sysfs.GetNetworkDevices()
89 if err != nil {
90 return nil, err
91 }
92 netDevices := []info.NetInfo{}
... ...
➜ ~ cat /sys/class/net/eth0/address
f0:76:1c:6d:26:d6
➜ ~ cat /sys/class/net/eth0/mtu
1500
➜ ~ cat /sys/class/net/eth0/speed
10
- system UUID
/sys/class/dmi/id/product_uuid
➜ ~ sudo cat /sys/class/dmi/id/product_uuid
F27316D5-4DB3-E411-A26A-F0761C6D26D6
➜ ~
Docker Info
# github.com/google/cadvisor/manager/manager.go
201 // Start the container manager.
202 func (self *manager) Start() error {
203 // Register Docker container factory.
204 err := docker.Register(self, self.fsInfo)
205 if err != nil {
206 glog.Errorf("Docker container factory registration failed: %v.", err)
207 }
... ...
cAdvisor 启动 container manager，通过调用 Linux 系统 inotify 监测 cgroup docker 目录的文件变化判断 docker 的创建和删除。
Getprocesslist
cAdvisor 首先判断自己是否运行在 container 中，如果是则 chroot /rootfs （cAdvisor 在 container 中运行会通过 volume 方式把系统 / mount 到 /rootfs 下）再执行 ps -e -o user,pid,ppid,stime,pcpu,pmem,rss,vsz,stat,time,comm,cgrou，否则直接执行获取。(github.com/google/cadvisor/manager/container.go GetProcessList() 函数实现)
# github.com/google/cadvisor/manager/manager.go
687 func (m *manager) GetProcessList(containerName string, options v2.RequestOptions) ([]v2.ProcessInfo, error) {
688 // override recursive. Only support single container listing.
689 options.Recursive = false
690 conts, err := m.getRequestedContainers(containerName, options)
691 if err != nil {
692 return nil, err
693 }
694 if len(conts) != 1 {
695 return nil, fmt.Errorf("Expected the request to match only one container")
696 }
... ...
如果是获取全局而非某个 container 的 processlist，则 containername 默认为 "/"，判断逻辑如下：
# github.com/google/cadvisor/manager/container.go
273 if isRoot || c.info.Name == cgroup {
274 processes = append(processes, v2.ProcessInfo{
275 User: fields[0],
276 Pid: pid,
277 Ppid: ppid,
278 StartTime: fields[3],
279 PercentCpu: float32(percentCpu),
... ...
ContainerInfo
获取指定 container 的 info 数据：
# github.com/google/cadvisor manager/manager.go
531 func (self *manager) DockerContainer(containerName string, query *info.ContainerInfoRequest) (info.ContainerInfo, error) {
532 container, err := self.getDockerContainer(containerName)
533 if err != nil {
534 return info.ContainerInfo{}, err
535 }
536
... ...
具体获取函数：
# github.com/google/cadvisor/manager/container.go
102 func (c *containerData) GetInfo() (*containerInfo, error) {
103 // Get spec and subcontainers.
104 if time.Since(c.lastUpdatedTime) > 5*time.Second { // 可以看出当上一次更新时间超过 5s 的时候才会更新 info 数据 5
105 err := c.updateSpec()
106 if err != nil {
107 return nil, err
108 }
... ...
- ContainerSpec
cAdvisor 获取 ContainerSpec 总体的逻辑是找出对应 container 对应的系统 Spec json 文件。
container info handler：
# github.com/google/cadvisor/container/docker/handler.go
220 func (self *dockerContainerHandler) GetSpec() (info.ContainerSpec, error) {
221 mi, err := self.machineInfoFactory.GetMachineInfo()
222 if err != nil {
223 return info.ContainerSpec{}, err
224 }
/proc/self/mountinfo当前运行进程的挂载信息/proc/cgroups当前内核支持的 cgroup 类型- libcontainer configpath
/var/run/docker/execdriver/native/containerId
# github.com/google/cadvisor/container/libcontainer/compatibility.go 读取 libcontainer config 文件信息
150 func ReadConfig(dockerRoot, dockerRun, containerID string) (*configs.Config, error) {
151 // Try using the new config if it is available.
152 configPath := configPath(dockerRun, containerID)
153 if utils.FileExists(configPath) {
154 out, err := ioutil.ReadFile(configPath)
155 if err != nil {
156 return nil, err
157 }
158
159 var state libcontainer.State
160 err = json.Unmarshal(out, &state)
161 if err != nil {
162 return nil, err
163 }
164 return &state.Config, nil
165 }
# github.com/google/cadvisor/container/docker/handler.go 磁盘使用率统计目前支持 aufs，这是目前 CentOS7 上没有 filesystem 大小的原因
... ...
232 // For now only enable for aufs filesystems
233 spec.HasFilesystem = self.storageDriver == aufsStorageDriver
... ...
241 func (self *dockerContainerHandler) getFsStats(stats *info.ContainerStats) error {
242 // No support for non-aufs storage drivers.
243 if self.storageDriver != aufsStorageDriver {
244 return nil
245 }
... ...
-
文件系统相关
# github.com/google/cadvisor/fs/fs.go -
aufs storage dir:
/var/lib/docker/aufs/diff/containerId -
获取 cgroup 和 网络状态
# github.com/google/cadvisor/container/docker/handler.go
# cgroup 信息是调用 github.com/docker/libcontainer/cgroups 获取
276 func (self *dockerContainerHandler) GetStats() (*info.ContainerStats, error) {
277 stats, err := containerLibcontainer.GetStats(self.cgroupManager, self.rootFs, self.pid)
278 if err != nil {
279 return stats, err
280 }
281 // Clean up stats for containers that don't have their own network - this
282 // includes containers running in Kubernetes pods that use the network of the
283 // infrastructure container. This stops metrics being reported multiple times
284 // for each container in a pod. 如果 container 没有自己的网络，则返回空。对于 K8s pod 内部 container 都是通过 pause container 网络通信
285 if !hasNet(self.networkMode) {
286 stats.Network = info.NetworkStats{}
287 }
288
289 // Get filesystem stats.
290 err = self.getFsStats(stats)
291 if err != nil {
292 return stats, err
293 }
294
295 return stats, nil
296 }
具体获取 cgroup 和 network 的函数实现 GetStats()
- container 网络状态
/proc/<pid>/net/dev
# github.com/google/cadvisor/container/libcontainer/helpers.go
81 // Get cgroup and networking stats of the specified container
82 func GetStats(cgroupManager cgroups.Manager, rootFs string, pid int) (*info.ContainerStats, error) {
83 cgroupStats, err := cgroupManager.GetStats()
84 if err != nil {
85 return nil, err
86 }
87 libcontainerStats := &libcontainer.Stats{
88 CgroupStats: cgroupStats,
89 }
90 stats := toContainerStats(libcontainerStats)
91
92 // If we know the pid then get network stats from /proc/<pid>/net/dev
93 if pid > 0 {
94 netStats, err := networkStatsFromProc(rootFs, pid)
95 if err != nil {
96 glog.V(2).Infof("Unable to get network stats from pid %d: %v", pid, err)
97 } else {
98 stats.Network.Interfaces = append(stats.Network.Interfaces, netStats...)
99 }
... ...
cgroup status 包含信息如下(cadVisor 调用 licontainer/cgroups 获取 container 对应 cgroup 信息)：
# github.com/docker/libcontainer/cgroups/stats.go
88 func NewStats() *Stats {
89 memoryStats := MemoryStats{Stats: make(map[string]uint64)}
90 hugetlbStats := make(map[string]HugetlbStats)
91 return &Stats{MemoryStats: memoryStats, HugetlbStats: hugetlbStats}
92 }